The crankshaft turns, but the engine does not start
Circuit Description
In the diagnostic table "The crankshaft turns, but the engine does not start" a method for detecting a malfunction that prevents the engine from starting is systematized. In the diagnostic table "The crankshaft turns, but the engine does not start" contains instructions on how to perform the appropriate system diagnostics by a service center specialist.
In the diagnostic table "The crankshaft turns, but the engine does not start" it is assumed that the following conditions are met:
- The batteries are fully charged.
- The frequency of rotation of the crankshaft when starting the engine meets the technical requirements.
- There is enough fuel in the fuel tanks.
Diagnostic Information
If the cause of the malfunction "The crankshaft turns, but the engine does not start" is not detected, check for the following faults:
Difficult start-up only at low ambient temperatures. This may be due to an intermittent malfunction that does not occur in a service center environment:
- Fuel heater not working
- Blockage of ice in the fuel receiver in the fuel tank. This fault will increase the vacuum in the supply lines when the engine is started and will disappear when the car is in the service center. This may also appear as a malfunction of the form "starting and stopping the engine" or starting failure without acceleration.
- Water or foreign matter in the fuel system
- General engine fault
Description of the test
The number below refers to the step numbers from the diagnosis table.
5. This step checks to see if ignition 1 voltage is applied to the ECM.
7. In some cases, lack of compression, possibly over-fueled, in any one cylinder can cause the engine to not start.
The crankshaft turns, but the engine does not start
Step | Operation | Values | Yes | No |
1 |
Have you performed a diagnostic system check?
|
-
|
Go to operation 2
|
Go to item "Diagnostic system check".
|
2 |
Does the scan tool display show DTCs related to fuel pressure regulator, fuel rail pressure sensor (FRP), CKP sensor, CMP sensor, ECM internal fault, 5V reference circuits, glow plug controller, or immobilizer signal to turn on fuel?
|
-
|
Jump to the appropriate DTC table
|
Go to operation 3
|
3 |
Are there customer complaints about smell or fuel leakage?
|
-
|
Go to section "Fuel leaks"
|
Go to operation 4
|
4 |
Determine parameter value from scan tool "Actual pressure in the fuel rail" (Actual Fuel Rail Pressure).
Does the parameter have a set value?
|
0.5 V
|
Go to operation 5
|
Jump to operation 10
|
5 |
Check parameter value with scan tool "Ignition signal 1" (Ignition 1 signal)
Does the parameter "Ignition signal 1" set value?
|
0.5V
|
Go to operation 6
|
Jump to operation 13
|
6 |
Check the following:
Fault found and corrected?
|
-
|
Jump to operation 19
|
Jump to Operation 7
|
7 |
Perform an engine compression test
Fault found and corrected?
|
-
|
Jump to operation 20
|
Jump to operation 8
|
8 |
Important: If the signal circuits or the low reference circuits of the crankshaft position sensor (CKP) there is high resistance, the scan tool will display for parameter "Engine speed" (Engine Speed) value greater than 0. This will not be an accurate measurement of engine speed and may cause a malfunction such as "The crankshaft turns, but the engine does not start".
Test for high resistance on the crankshaft position sensor signal and low reference circuits.
Fault found and corrected?
|
-
|
Jump to operation 19
|
Go to operation 9
|
9 |
Check the following:
Fault found and corrected?
|
-
|
Jump to operation 19
|
Go to Diagnostic Information
|
10 |
Parameter value "Actual pressure in the fuel rail" less than the set value?
|
-
|
Go to operation 11
|
Go to operation 12
|
11 |
Test the fuel rail pressure sensor signal circuit for a short to "mass".
Fault found and corrected?
|
-
|
Jump to operation 19
|
Jump to operation 16
|
12 |
Test for high resistance fuel rail pressure sensor signal circuits.
Fault found and corrected?
|
-
|
Jump to operation 19
|
Go to operation 14
|
13 |
Fault found and corrected?
|
-
|
Jump to operation 19
|
Jump to operation 15
|
14 |
Check the fuel rail pressure sensor for an intermittent or poor connection.
Fault found and corrected?
|
-
|
Jump to operation 19
|
Go to operation 17
|
15 |
Does the engine start?
|
-
|
Jump to operation 19
|
Jump to operation 16
|
16 |
Check the ECM for intermittent faults or loose connections.
Fault found and corrected?
|
-
|
Jump to operation 19
|
Go to operation 18
|
17 |
Replace fuel rail pressure sensor.
Has the replacement been made?
|
-
|
Jump to operation 19
|
-
|
18 |
Replace the ECM.
Has the replacement been made?
|
-
|
Jump to operation 19
|
-
|
19 |
Does the engine start and continue to run?
|
-
|
Jump to operation 20
|
Go to operation 2
|
20 |
Are any DTCs shown on the display?
|
-
|
Jump to the appropriate DTC table
|
System OK
|
Fuel Rail Pressure Regulator Diagnosis
Plotting a fuel rail pressure regulator provides valuable information about regulator performance by comparing desired and actual fuel rail pressures. Comparison of the actual and required fuel rail pressure gives an almost ideal result for a relatively new engine with a short operating life. Small pulsations are acceptable for the fuel rail pressure regulator and are found in engines with a long service life. Sharp fluctuations in the actual pressure in the fuel rail indicate a stuck pressure regulator.
1. Start the engine and let it idle.
2. Check the scan tool graph for sudden changes or fluctuations in the actual fuel pressure at the fuel rail by doing the following at the same time:
- The engine is idling
- Switching the gearbox to positions from "parking" before "movements" and back to "parking lot"
- Rotation of the steering wheel from the left end position to the right end position.
- Turning the air conditioning on and off
7. If the graph shows strong fluctuations in the actual pressure in the fuel rail, similar to the sharp pulsations shown in the graph below, then the fuel pressure regulator must be replaced.
Graph for a serviceable fuel pressure regulator; new motor with short service life
1. Actual pressure in the fuel rail
2. Required fuel rail pressure
Graph for a serviceable fuel pressure regulator; long life engine
1. Actual pressure in the fuel rail
2. Required fuel rail pressure
Graph for stuck fuel pressure regulator
1. Actual pressure in the fuel rail
2. Required fuel rail pressure
Fuel Pump Electrical Circuit Diagnosis
Description of circuits / systems
The electric fuel pump is used to prime the fuel system after changing the fuel filter or servicing the fuel system. Power is supplied to the fuel pump through the fuel pump relay. The fuel pump relay is controlled by the ECM. The ECM turns on the fuel pump when the ignition is turned on and will continue to control it for some time or until the engine starts. If the ignition is left on "incl.", the pump will run for about four seconds. In addition, the ECM will turn OFF the fuel pump if it detects a voltage in the control circuit that is not equal to the required voltage. The ECM will need to be turned off by the key during diagnosis or after repair before it can command the fuel pump to turn on again.
Diagnostic Information
A blown fuel pump fuse can be caused by the following reasons:
- Fuse defective
- Intermittent short circuit to "mass" in the voltage supply circuit to the fuel pump
- Intermittent internal fuel pump fault
Circuit / system test
1. Check fuel pump fuse.
2. If there is an open in the fuel pump fuse, check for an open circuit in the battery positive circuit and the fuel pump voltage supply circuit for a short to "mass" And is the fuel pump good?
3. Switch on the ignition with the engine off.
4. Command the fuel pump with a scan tool "incl." And "off" The fuel pump relay should click, turning on and off with each command.
5. If the fuel pump is running continuously, test the relay for a good condition and for a short to live wire in the fuel pump voltage supply circuit.
6. If the fuel pump does not turn on and off, replace the fuel pump relay.
7. Check the battery positive circuit at the fuel pump relay with a test light connected to a good connection point on "mass".
8. If the test lamp does not illuminate, repair the open in the positive battery terminal circuit.
9. Connect a fused jumper wire between the battery positive circuit and the fuel pump relay voltage supply circuit.
10. If the fuel pump is running, check for an intermittent or poor connection at the fuel pump relay and if the relay is OK.
11. If the fuel pump does not operate, test for an open or high resistance in the supply voltage circuit or in the power supply circuit "mass" fuel pump.
12. If no faults are found on all circuit tests and the fuel pump relay is working properly, replace the fuel pump.
Fuel system diagnostics
Description of the fuel system
Fuel is taken by the pump through the strainer located in the fuel tank, located in front of the fuel filter, and supplied to the engine through the fuel pipelines. The fuel passes through the fuel filter/heater housing, which combines the water separator, fuel heater heating element and filter element. The fuel then enters the high pressure fuel pump for fuel injection. Scan tool control output function, or repeated switching of the ignition key to positions "incl." / "off" are used, after performing a fuel filter change or fuel system maintenance, to prime the fuel system by activating the fuel pump with the engine stopped. If the fuel system is not supplying enough fuel, the vehicle's handling may be impaired. If air is sucked into the fuel injection system, then a symptom of a malfunction such as "The crankshaft turns, but the engine does not start" or "Difficult start".
High pressure system
The fuel injection pump is driven by the engine via the timing belt. From the high pressure injection pump, pressurized fuel enters the common rail. The common rail delivers pressurized fuel to the fuel injectors. A fuel rail pressure sensor is installed on the common rail (FRP).
Fuel return system
The fuel return system takes fuel from the fuel injectors, the common rail, and the fuel injection pump. A fuel pressure regulator is installed in the common rail. The returned fuel enters the fuel tank. If the fuel pressure on the high pressure side of the system becomes excessively high, the pressure regulator will dump fuel into the return system.
Diagnostic Information
The penetration of air into the fuel system can occur for the following reasons:
- Deformations or cuts in the sealing rings in the connections of the fuel supply lines
- Incorrectly installed fuel supply fittings
- Porous or weathered rubber fuel supply lines
Circuit / system test
1. Disconnect the fuel supply line from the fuel injection pump.
2. Install a fuel pressure gauge between the fuel injection pump inlet and the fuel supply line.
3. Perform initial filling of the fuel system.
4. Using a scan tool, turn on the fuel pump and check the gauge for fuel pressure. Inspect the engine and chassis for leaks or damage to the fuel hoses, fuel lines, and fuel system components.
- 5. Repair leaks or replace any components found to be damaged or leaking.
6. If the fuel pump did not work and there was no fuel pressure, then refer to paragraph «Fuel Pump Electrical Circuit Diagnosis".
7. If the fuel pump started and there was no fuel pressure, then check for a vacuum leak from the fuel supply line.
8. If there are no leaks or damage in the fuel system, turn off the fuel pump and remove the fuel pressure gauge.
9. Install a transparent hose between the fuel injection pump inlet and the fuel supply line. Bend the hose into a vertical loop in which it would be possible to determine if there are air bubbles in the incoming fuel.
10. Using a scan tool, turn on the fuel pump and prime the fuel system until all air is purged from the system. Start the engine and let it run for at least 10 minutes to allow conditions in the fuel system to stabilize.
11. If air bubbles are observed in the transparent hose, then check for a leak in the fuel level sensor.
12. If air bubbles do not disappear after replacing the fuel level sensor, refer to the section "Diagnostic Information".
13. If air bubbles disappear after replacing the fuel level sensor, remove the transparent hose and start the engine to check for fuel leaks.
Diagnostics of the fuel return system
Description of the fuel system
Fuel is taken by the pump through the strainer located in the fuel tank, located in front of the fuel filter, and supplied to the engine through the fuel pipelines. The fuel passes through the fuel filter/heater housing, which combines the water separator, fuel heater heating element and filter element. The fuel then enters the high pressure fuel pump for fuel injection. Scan tool control output function, or repeated switching of the ignition key to positions "incl." / "off" are used, after performing a fuel filter change or fuel system maintenance, to prime the fuel system by activating the fuel pump with the engine stopped. If the fuel system is not supplying enough fuel, the vehicle's handling may be impaired. If air is sucked into the fuel injection system, then a symptom of a malfunction such as "The crankshaft turns, but the engine does not start" or "Difficult start".
High pressure system
The fuel injection pump is driven by the engine via the timing belt. From the high pressure injection pump, pressurized fuel enters the common rail. The common rail delivers pressurized fuel to the fuel injectors. A fuel rail pressure sensor is installed on the common rail (FRP).
Fuel return system
The fuel return system takes fuel from the fuel injectors, the common rail, and the fuel injection pump. A fuel pressure regulator is installed in the common rail. The returned fuel enters the fuel tank. If the fuel pressure on the high pressure side of the system becomes excessively high, the pressure regulator will dump fuel into the return system.
Diagnostic Information
Bent or kinked engine fuel return lines can cause difficult fuel return.
Diagnostics of the fuel return system
Step | Operation | Values | Yes | No |
1 |
Important: Do not apply more air pressure to the return line than required.
Is air escaping through the fill pipe?
|
-
|
Go to operation 6
|
Go to operation 2
|
2 |
Is air escaping through the fuel return line?
|
-
|
Go to operation 3
|
Go to operation 4
|
3 |
Remove fuel sensor assembly
Has the replacement been made?
|
-
|
Go to operation 6
|
-
|
4 |
Fault found and corrected?
|
-
|
Go to operation 6
|
Go to operation 5
|
5 |
Replace fuel return line between engine and fuel tank.
Has the replacement been made?
|
-
|
Go to operation 6
|
-
|
6 |
Has the problem been resolved?
|
-
|
System OK
|
Jump to the appropriate DTC table
|
Fuel leaks
1. Remove the air filter assembly.
2. Clean all fuel lines between fuel injection pump and fuel injectors with brake cleaner and dry.
3. Add 250 ml of oil coloring to the fuel tank.
4. Start the engine and let it idle for 3-5 minutes.
- 5. Check for leaks around the fuel injection pump, fuel rail and fuel injector feed pipes. Tighten or replace leaking lines or components.
6. A fuel leak can be caused by obstruction of fuel flow in the fuel return lines.
Checking Injector Balance Using a Scan Tool (cylinder compression test)
Circuit Description
In case of deviations in the balance of the cylinders from the norm, it is possible to perform a check using a scanning tool that allows you to localize the cause of the deviation. In order to determine if the cause is related to the engine or the injection system, a compression test can be used. If the problem is found to be related to the injectors, then further testing can determine which injector failure caused the cylinder balance to be abnormal.
Check includes 3 modes (A, B, C), that are used in various conditions.
Circuit / system test
Using a scan tool, perform a compression test following the instructions on the display.
Mode A: determining the angular velocity for each of the cylinders during the compression test
Fuel injection to all injectors is disabled in order to perform a compression test with the starter without starting the engine. The angular velocity of the engine is determined for each top dead center. A lower engine speed determined for one cylinder compared to others indicates higher compression in that cylinder. The higher the engine speed determined for any cylinder, the lower the compression in it. In this test, the correction values used to control the fuel trim (FCB), are equal to zero. Note that this test is intended to determine the relative performance of each cylinder. The higher or lower compression discussed here will not necessarily also be obtained when determining the actual compression in the engine cylinders using a pressure gauge.
Mode B: determination of the quantitative correction for each of the cylinders
In this test mode, the engine is operated using the correction values used to control the fuel trim (FCB). Quantity correction is a correction value added to the amount of fuel injected to maintain an acceptable level of engine vibration. The speed of rotation of the engine shaft for each of the cylinders is also determined. A higher trim quantity indicates an injector that takes longer to inject the amount of fuel needed to produce the desired engine torque.
Mode C: determination of angular velocities for each of the cylinders without the use of correction balancing values
In this test mode, the engine is running without using the correction values used to control the fuel trim (FCB). It is possible to continuously determine the engine speed for each of the cylinders and the behavior of the engine during operation without the use of FCB correction values.
Diagnostics of contaminants in fuel
Fungi and other microorganisms can survive and multiply in diesel fuel if it contains water. Fungi can be found anywhere in the fuel system. These fungi grow in long filaments that then form into large spherical particles. The sprouts look sticky and are usually black, green, or brown in color. Fungi can grow in fuel everywhere, but they thrive especially where there is diesel fuel with water. Since the fuel is mixed when filling the tanks, the fungi are distributed throughout the entire volume of the tank and can be pumped into the car. Fungi use fuel as their main source of energy and require only trace amounts of water and minerals. As they grow and multiply, they convert fuel into water, sludge, acids, and metabolic products. The most common symptom is a clogged fuel filter, but corrosion can also occur on various metal parts of the fuel system, including the fuel gauge, pipes, fuel injectors, and fuel injection pump.
CAREFULLY! Physical contact with biocides must be avoided to avoid personal injury.
If the fungus has contaminated the fuel system, biocides designed for diesel fuel must be used to sterilize it. It is not allowed to exceed the dose indicated on the package. The use of the biocide should be discontinued if a trailer is towed. The presence of biocide in the fuel is acceptable at the start of towing, but biocide should not be added during the towing period.
If the majority of fungal growth cannot be removed with biocides, then steam cleaning may be necessary.
The presence of water or gasoline in diesel fuel can also damage the injection pump and fuel injectors.
This procedure checks for the presence of water and gasoline in diesel fuel, which can cause damage to the injection pump and fuel injectors.
Remove and inspect the fuel filter.
- If water, gasoline or fungus/bacteria are not present, then complete inspection.
- If there is water or fungi / bacteria, then go to the section "Removing water from the fuel system".
- If you have gasoline, then go to the section "Removing gasoline from the fuel system".
Removing water from the fuel system
1. Disconnect the negative battery cable.
2. Remove the sensor block.
3. Inspect the fuel tank and fuel gauge for corrosion, fungus or bacteria. If any components are found to be corroded, replace those components.
4. Rinse the inside of the fuel tank and the fuel level sensor with hot water.
5. Dry the fuel tank and fuel level sensor with compressed air.
6. Disconnect the ends of the following pipelines:
- Fuel filter inlet pipe (both ends)
- Fuel filter outlet pipe (both ends)
- Fuel return line (both ends)
7. Inspect each tube and line.
8. Replace tubes that are corroded.
9. Clean the inside of the fuel filter housing.
10. Dry the fuel filter housing with compressed air.
11. Dry the inside of each pipeline with air at low pressure.
12. Remove ignition relay 1.
13. Install a new fuel filter.
14. Install the sensor block.
15. Top up the main fuel tank with clean diesel fuel until it is ½ full.
16. Connect the following pipes:
- Fuel filter inlet pipe
- Fuel filter outlet pipe
- Fuel return line (to the fuel tank)
17. Connect batteries.
18. Perform initial filling of the fuel system.
19. Connect the hose to the fuel return line at the engine, and lower the other end into a metal container with a volume of 7.6 liters (2 gallons).
20. Crank the engine in periods of 30 seconds with 1 minute breaks to cool. Continue until 3.8 liters are poured into the container (1 gallon) fuel.
21. Connect fuel return line.
22. Install ignition relay 1.
23. Start the engine.
24. Stop the engine.
25. Remove any fuel spilled from the engine.
26. Fill the tank with fuel and add biocide if necessary.
Removing gasoline from the fuel system
1. Drain fuel from tank.
2. Fill the fuel tank to?.
3. Remove ignition relay 1.
4. Open the fuel filter drain and connect a hose to the filter, the other end of which is lowered into a metal container.
5. Turn on the fuel pump with a scan tool and wait for clean fuel to flow from the fuel filter into the container.
6. Close the fuel filter drain and disconnect the hose.
7. Connect the hose to the fuel return line at the engine, and lower the other end into a metal container with a volume of 7.6 liters (2 gallons).
8. Crank the engine in periods of 30 seconds with 1 minute breaks to cool. Continue until 3.8 liters are poured into the container (1 gallon) fuel.
9. Connect fuel return line.
10. Install ignition relay 1.
11. Try to start the engine and leave it running for 15 minutes. If the engine does not start, then prime the fuel system.
12. Stop the engine.
13. Remove any fuel spilled from the engine.
14. Clear all engine DTCs.
Fuel heater not working
Circuit Description
The combined fuel filter assembly consists of a fuel heater, a water-in-fuel sensor, and a filter. The filter contains a coalescer, a device that turns small water droplets into larger ones, and a filter/separator.
The fuel entering the filter passes through the fuel heater. The heater has a thermostatic switch, which, when opened or closed, switches the heater off or on depending on the fuel temperature.
The fuel then passes through a filter and a water coagulator where the water droplets contained in the fuel are converted into larger droplets that fall into a sump contained in the filter. The fuel combination filter unit supplies clean, water-free fuel to the high pressure pump.
The fuel heater is controlled by the ECM. The fuel temperature sensor is an NTC thermistor; The sensor sends fuel temperature information to the ECM.
Step | Operation | Values | Yes | No |
1 |
Have you performed a diagnostic system check?
|
-
|
Go to operation 2
|
Go to item "Diagnostic system check".
|
2 |
Is the control lamp on?
|
-
|
Go to operation 3
|
Go to operation 5
|
3 |
Check circuit "masses" fuel heater using a test lamp connected to B+.
Is the control lamp on?
|
-
|
Go to operation 4
|
Jump to Operation 7
|
4 |
Is the temperature of the fuel heater increasing?
|
-
|
Go to operation 9
|
Jump to operation 8
|
5 |
Repair the open in the ignition 1 voltage circuit between the fuel heater harness connector and the fuse.
Repair completed?
|
-
|
Go to operation 9
|
-
|
6 |
Eliminate short circuit "mass" in the ignition voltage circuit 1.
Repair completed?
|
-
|
Go to operation 9
|
-
|
7 |
Repair an open circuit in the connection to "weight" between the fuel heater harness connector and "weight" chassis.
Repair completed?
|
-
|
Go to operation 9
|
-
|
8 |
Replace fuel heater.
Has the replacement been made?
|
-
|
Go to operation 9
|
-
|
9 |
Carry out a trip with the vehicle on which the malfunction was noticed.
Is the system functioning properly?
|
-
|
System OK
|
Go to operation 2
|
Data link messages
This table shows which serial data channel a particular module uses when transmitting data on a vehicle. Some modules may use more than one data link for communication. Some modules may have multiple communication paths passing through them without actively interacting with that data link. This table is for use in troubleshooting communication problems.
Controller
|
Data link type
|
Name of the diagnostic procedure
|
Body electronics control unit (BCM)
|
High Speed GMLAN / Low Speed GMLAN
|
Scan Tool Not Communicating with High Speed GMLAN Device
|
Electronic brake control (EBCM)
|
High Speed GMLAN
|
Scan Tool Not Communicating with High Speed GMLAN Device
|
Electronic climate control unit (ECC)
|
Low Speed GMLAN
|
Scan Tool Not Communicating with Low Speed GMLAN Device
|
Electronic engine management controller (ECM)
|
High Speed GMLAN
|
Scan Tool Not Communicating with High Speed GMLAN Device
|
Export control unit for electronic body systems (XBCM)
|
Low Speed GMLAN
|
Scan Tool Not Communicating with Low Speed GMLAN Device
|
instrument cluster (IPC)
|
Low Speed GMLAN
|
Scan Tool Not Communicating with Low Speed GMLAN Device
|
Remote execution of functions (RFA)
|
Low Speed GMLAN
|
Scan Tool Not Communicating with Low Speed GMLAN Device
|
Block of information and diagnostics (SDM)
|
Low Speed GMLAN
|
Scan Tool Not Communicating with Low Speed GMLAN Device
|
Gearbox controller (TCM)
|
High Speed GMLAN
|
Scan Tool Not Communicating with High Speed GMLAN Device
|
Transfer box controller (TCCM)
|
High Speed GMLAN
|
Scan Tool Not Communicating with High Speed GMLAN Device
|
Car alarm system controller (VTD)
|
Low Speed GMLAN
|
Scan Tool Not Communicating with Low Speed GMLAN Device
|
Scan tool does not turn on
Circuit Description
As a diagnostic block (DLC) uses a standard 16-pin connector. Connector design and location are dictated by industry standard and should provide the following:
- Battery positive to power the scan tool on pin 16.
- Connection to "mass" scan tool power on pin 4.
- General signal "weight" on pin 5.
The scan tool is turned on when the ignition is turned off. However, communication with some controllers will be lost until the ignition is turned on, and from the main power mode controller (PMM) message about the corresponding power mode will not be sent.
Description of the test
The number below refers to the stage number from the diagnostic table.
Step | Operation | Values | Yes | No |
1 |
Test the battery positive terminal circuit in the diagnostic terminal for an open or short to "mass".
Fault found and corrected?
|
-
|
Go to item "Diagnostic system check".
|
Go to operation 2
|
2 |
Check circuits "masses" diagnostic pad for a break and the presence of high resistance.
Fault found and corrected?
|
-
|
Go to item "Diagnostic system check".
|
Go to operation 3
|
3 |
Check the diagnostic block for poor connections and unreliable mechanical connections of the contacts.
Fault found and corrected?
|
-
|
Go to item "Diagnostic system check".
|
Go to operation 4
|
4 |
There may be a problem with the scanning tool. Refer to the operating instructions for the scanning instrument.
Did you receive a valid scan tool?
|
-
|
Go to item "Diagnostic system check".
|
-
|
Scan Tool Not Communicating with High Speed GMLAN Device
Circuit Description
The GMLAN serial data network circuits are high-speed serial data busses of the CAN protocol network used to transfer information between controllers. Typical data rates must be high enough to provide the required real-time response rate. There are 2 very different types of GMLAN serial data network circuits on this vehicle: a high speed 2-wire data circuit and a low speed single wire circuit. The GMLAN serial data network circuits are also directly connected to the diagnostic block (DLC). The messages are interpreted by an external CANdi module, which serves as a transmitter for the scan tool.
Modules connected to the GMLAN's high-speed serial data circuits monitor the serial communications during normal vehicle operation. The exchange of operational information and commands between the controllers occurs if the ignition switch is in any position except "off" GMLAN high speed serial data circuits are required at engine start for communication between the body electronics control module (BCM) and the ECM controller. Car alarm system controller (VTD) and the ECM communicate through the BCM acting as a gateway module that provides communication between the high and low speed serial buses. A low speed GMLAN serial data network circuit is also required to start the engine. The GMLAN high speed serial bus uses two 120 ohm terminating resistors in parallel with the circuits (+) And (-) high speed GMLAN.
Diagnostic Information
- Use "Data link messages" to identify high-speed GMLAN serial data network modules.
- When checking for a short circuit between circuits (+) And (-) high speed GMLAN (ECM disabled) normal is a resistance of 120 ohms. When checking for a short to a live wire or "mass" chains (+) And (-) High Speed GMLAN requires that all controllers, resistors, and the scan tool be disconnected from the bus. When measuring resistance between high-speed GMLAN data bus circuits with resistors disconnected, all controllers, and the scan tool, infinite resistance is the normal result.
- This test is used in the event of a general failure of the high speed GMLAN data network. If only 1 controller is not communicating and the DTC does not set, verify that the vehicle is equipped with this controller and then use DTC U0100-U0299 to diagnose.
- Use the DMM's MIN/MAX function to locate and isolate an intermittent fault.
- The engine will not start in the event of a general GMLAN bus failure. A general communication failure over a high-speed GMLAN data network can occur for the following reasons:
- Short circuit between circuits (+) And (-) high speed GMLAN.
- Short circuit on "mass" or at "voltage" any of the high speed GMLAN serial data circuits.
- Controller internal fault causing a short to "mass" or at "voltage" high-speed GMLAN serial data circuits.
- Malfunction of the block of management of electronic systems of a body (BCM)
Circuit / system test
1. Using a scan tool, verify that all high speed data network controllers are not communicating.
- If any of the high-speed network controllers is communicating and any DTC is set that begins with the letter "U", refer to the appropriate DTC table for diagnosis.
- If any of the high-speed network controllers are communicating and no DTCs starting with the letter are set "U", then use to diagnose DTC U0100-U0299.
2. Check resistance between circuit pin 5 "masses" diagnostic pads and "weight", which should be less than 1 ohm.
- If more than 1 ohm, then check the circuit "masses" open / high resistance.
3. Ignition OFF, disconnect the BCM harness connector (BCM).
4. Ignition ON, check battery voltage between each BCM voltage input circuit and "weight".
- If voltage is less than battery voltage, test each of the BCM voltage supply output circuits for a short to "mass", and each of the input circuits for supplying voltage to the BCM for a short to "mass" and open / high resistance.
5. Check the resistance between each connection circuit to "mass" BCM and "weight", which should be less than 1 ohm.
- If more than 1 ohm, then repair the open / high resistance in the connection circuit to "mass".
6. Switch off the ignition. Disconnect the harness connector from the BCM. Disconnect the transfer box controller connector (TCCM), if installed on an AWD model, or terminating resistor connector if installed on a FWD model.
7. Attempt to communicate with the BCM. There must be no connection.
- If communication is established, then replace the TCCM or terminating resistor.
8. Check the serial data circuits for a short to each other, a short to "mass" and for closing "for voltage" between the BCM and the TCCM or terminating resistor.
9. Ignition OFF, disconnect the ECM harness connector.
10. Attempt to communicate with the BCM. There must be no connection.
- If communication is established, replace the ECM.
11. Ignition OFF, disconnect TCM harness connector (TCM)
12. Attempt to communicate with the BCM. There must be no connection.
- If communication is established, test the serial data circuits for a short to each other, a short to "mass" and for closing "for voltage" between the ECM and the TCM. If the circuits test normal, replace the ECM.
13. Ignition OFF, disconnect ECM harness connector (EBCM).
14. Attempt to communicate with the BCM. There must be no connection.
- If communication is established, test the serial data circuits for a short to each other, a short to "mass" and for closing "for voltage" between the TCM controller and the electronic brake control unit (EBCM). If the circuits test normal, replace the EBCM.
15. Ignition OFF, disconnect the BCM harness connector (BCM).
16. Check the voltage between the serial data circuits of the high speed GMLAN network of the diagnostic terminal and "weight", which must be less than 1.0 V.
- If greater than 1.0 V, repair the serial data circuit for a short to live.
17. Check the resistance between the GMLAN serial data circuit of the diagnostic terminal and "weight", which must be infinitely large.
- If the resistance is less than infinite, then repair the serial data circuit short to "mass".
18. Check resistance between circuits (+) And (-) GMLAN serial data network on the diagnostic block, which should be infinitely large.
- If the resistance is less than infinite, then eliminate the short circuit of the serial data circuits to each other.
19. If no fault is found during circuit testing, replace the BCM.
Scan Tool Not Communicating with Low Speed GMLAN Device
Circuit Description
The GMLAN serial data network circuits are high-speed serial data busses of the CAN protocol network used to transfer information between controllers. Typical data rates must be high enough to provide the required real-time response rate. There are 2 very different types of GMLAN serial data network circuits on this vehicle: a high speed 2-wire data circuit and a low speed single wire circuit. The GMLAN serial data network circuits are also directly connected to the diagnostic block (DLC). The messages are interpreted by an external CANdi module, which serves as a transmitter for the scan tool.
Modules connected to the low speed GMLAN serial data circuit monitor the serial communication during normal vehicle operation. The exchange of operational information and commands between the controllers occurs if the ignition switch is in any position except "off" The GMLAN low speed serial data circuit is required when starting the engine for communication between the vehicle's alarm system controller (VTD) and control unit for electronic body systems (BCM).
Diagnostic Information
- Use "Data link messages" to detect low speed GMLAN serial data network modules.
- This test is used in the event of a general low rate GMLAN data link failure. If only 1 controller is not communicating and the DTC does not set, verify that the vehicle is equipped with this controller and then use DTC U0100-U0299 to diagnose.
- An open in the GMLAN low speed serial data link between the terminal block and the controller (-ami) will only affect the operation of a specific controller (-ov). With this type of malfunction, the diagnostic code will be set only for those controllers that are affected by this malfunction, and communication between the remaining controllers will be maintained. The vehicle may not be able to move, depending on which controller is affected.
- Exchange between diagnostic block (DLC) and terminal block will only affect communication with the scan tool. The connection between the modules will remain and the car will be able to move.
- Use the DMM's MIN/MAX function to locate and isolate an intermittent fault.
- The engine will not start in the event of a general failure of the low speed GMLAN data link circuit. General failure of the low-speed GMLAN data link can occur for the following reasons:
- Short circuit on "mass" or at "voltage" low-speed GMLAN serial data circuits.
- Controller internal fault causing a short to "mass" or at "voltage" low speed GMLAN serial data circuits.
Circuit / system test
1. Check resistance between circuit pin 5 "masses" diagnostic pads and "weight", which must be less than 1.0 ohm.
- If more than 1.0 ohm, then check the connection circuit to "mass" open / high resistance.
2. Ignition OFF, disconnect the harness connector from the low speed power terminal block.
3. Ignition ON, test for voltage between the GMLAN low speed serial data circuit of the diagnostic terminal and "weight", which must be less than 1.0 V.
- If greater than 1.0 V, repair the serial data circuit for a short to live.
4. Check the resistance between the connection circuit to "mass" diagnostic pads and "weight", which must be infinitely large.
- If the resistance is less than infinite, then repair the serial data circuit short to "mass".
5. Check the resistance in the serial communication circuit between the diagnostic block and the terminal block, which should be less than 1.0 ohms.
- If greater than 1.0 Ω, repair an open/high resistance in the serial communication circuit.
6. Connect a jumper with a 3 A fuse between pin 1 and pin 8 of the terminal block. Connect another jumper with a 3A fuse to pin 1.
7. Connect the free end of the additional jumper connected to pin 1 to the other pins of the terminal block in turn and try to establish communication with each of the controllers connected to the additional jumper. Communication must be available with at least one of the controllers.
- If you cannot communicate with any of the controllers, test the BCM serial data circuit for a short to a live wire or "mass" and open / high resistance. If no fault is found during circuit testing, replace the BCM.
- If communication cannot be established with a particular controller, then test the serial data circuit of the controller that is not communicating with for a short to a live wire or to "mass" and open / high resistance. If no fault is found during circuit testing, replace the BCM.
8. If no fault is found when testing all circuits, replace the terminal block.
Programming and initial installation of the ECM (diesel engine Z20S)
ECM Replacement
When replacing the ECM, do the following:
- ECM Programming (SPS programming)
- Alarm programming (immobilizer)
After programming a new ECM, do the following:
- Entering tire size (tire circumference coding)
- Entering the nozzle flow (programmable setting of quantitative parameters of injectors (IQA)) or IMA encoding. Check the scan tool stored injector flow rate before replacing the ECM and restore it to that value after programming the new ECM.
- Remaining engine oil life. Check the scan tool engine oil life history data before replacing the ECM and restore these values after programming the new ECM.
- Vehicle Configuration Programming
- Reset EEPROM Offset Values for No Fuel Injection Conditions (ZFC) and enabling ZFC fast detection mode.
- Resetting the EEPROM values for the diesel particulate filter (DPF)
Reprogramming the ECM
When reprogramming the ECM (ECM has not been replaced) you must enter the following values:
- After reprogramming the ECM, no special action is required.
Initial setting when replacing components
When replacing some components, you will need to follow the initial installation procedure provided for the case of a complete repair.
When replacing components, you must perform the following initial installation procedures:
- ECM Programming (SPS programming)
- Every time the ECM is replaced.
- Entering the remaining engine oil life
- At every engine oil change.
- Every time the ECM is replaced.
- Entering tire size (tire circumference coding)
- Each time you install tires that are different from the size of the previous tires.
- Reset EEPROM Offset Values for No Fuel Injection Conditions (ZFC)
- With every injector change.
- Every time the fuel rail pressure sensor is replaced (FRP) or the entire fuel rail. In this case, you must also enable the ZFC fast detection mode.
- Every time the ECM is replaced.
- Resetting the EEPROM values for the diesel particulate filter (DPF)
- Every time you change the diesel particulate filter (DPF).
- Every time the differential pressure sensor in the diesel particulate filter is replaced (DPF).
- With every injector change.
- Every time the ECM is replaced.
- Diesel particulate filter regeneration
- In each case of soot accumulation in excess of the maximum allowable value (48 g) and the resulting reduction in power. As a result, normal regeneration is suppressed and DTC P2463 is stored in memory.
- Whenever there is an accumulation of soot in the range of 24 to 48 grams and the following DTCs are stored in the memory. In such cases, regeneration is required, carried out at the service center after the appropriate repair or replacement is performed for each of the DTCs.
Sensor reference voltage
P060B, P0651
The exhaust gas temperature deviates from the set value
P1446, P1447, P244C, P244D
Intake air temperature sensor (IAT1)
P0110
Engine oil diluted
P253F
Nozzle
P0201, P0202, P0203, P0204, P062B, P1224, P1227, P122A, P1233, P2146, P2149,
Fuel system
P0087, P0088, P0089, P0090, P0190, P0191, P2293, P2294
DPF
P2031, P2080, P2084, P20E2, P2458, P2463
- Initial setting of fuel injector flow (programmable setting of quantitative parameters of injectors (IQA)) or IMA encoding.
- With every injector change.
- With each change in the position of the nozzles.
- Every time the ECM is replaced.
Diesel particulate filter regeneration (DPF)
If a vehicle delivered to a service center has active or inactive diesel particulate filter DTCs, a feature provided in the software that allows the scan tool to initiate a guided regeneration can be used to help identify components that require repair. In addition, if the accumulated amount of soot exceeded the maximum allowable value and this caused a decrease in power and disabling regeneration, then the service mode provides the only opportunity to regenerate the particulate filter and eliminate the decrease in power (the service mode does not require the fulfillment of many of the conditions necessary for normal regeneration while driving). The service mode is also useful for confirming the effectiveness of repairs to the diesel particulate filter system. When performing a service regeneration, the diesel particulate filter diagnostics are operational, and therefore the analysis of diagnostic trouble codes related to the diesel particulate filter helps to identify malfunctions, if any. If any DTCs are set, repair the problem and return to service mode.
Attention!
When performing a service regeneration, the exhaust pipe outlet temperature will exceed 550°C (1022°F). It is necessary that no one is near the exhaust pipe.
Place the car on an open and fireproof surface.
Improper application of the service regeneration mode can result in damage to the engine and exhaust system.
Do not perform service regeneration of the particulate filter if the vehicle has malfunctions that are not related to the particulate filter. Using the service regeneration mode with faulty engine components can damage the engine and exhaust system.
Before performing a service regeneration, make sure that no soot is coming from the end of the particulate filter. First, make sure there is no soot near the exhaust pipe. If there is soot, then inspect the exhaust pipe of the particulate filter. The presence of soot at the rear end of the cross section of the particulate filter means that its filtering ability has deteriorated dramatically. If soot comes from the end of the particulate filter, replace the filter.
Important:
Check the coolant level before and after the procedure.
After working in service mode, an oil change may be required. The oil viscosity will decrease after each service regeneration. There is a well-known rule of thumb that it is recommended to change the engine oil after a service regeneration if 80% of the planned period of time between oil changes has elapsed. In addition, if more than 3 service regenerations are carried out consecutively, the engine oil must be changed regardless of the remaining oil life.
After service regeneration, the vehicle must cool down. It is advisable to increase the engine speed to 1500 rpm so that the cooling of the exhaust system occurs more evenly and excessive heat generation can be avoided.
Diesel particulate filter regeneration procedure
1. Install the diagnostic tool.
2. Check coolant level.
3. Select the particulate filter regeneration service mode from the scan tool output control menu.
4. Follow the instructions that appear on the display of the scanning tool.
Note: If necessary, the procedure can be interrupted at any time by switching off the ignition. Depressing the brake pedal returns the engine to idle. If the scan tool is used to abort the procedure, the engine will slowly return to idle.
4. After the service regeneration of the particulate filter is completed, turn off the engine and let it cool down. It is advisable to increase the engine speed to 1500 rpm so that the cooling of the exhaust system occurs more evenly and excessive heat generation can be avoided.
5. Check coolant level.
- Short circuit on "mass" or at "voltage" low-speed GMLAN serial data circuits.
- Controller internal fault causing a short to "mass" or at "voltage" low speed GMLAN serial data circuits.
- Every time the ECM is replaced.
- At every engine oil change.
- Every time the ECM is replaced.
- Each time you install tires that are different from the size of the previous tires.
- With every injector change.
- Every time the fuel rail pressure sensor is replaced (FRP) or the entire fuel rail. In this case, you must also enable the ZFC fast detection mode.
- Every time the ECM is replaced.
- Every time you change the diesel particulate filter (DPF).
- Every time the differential pressure sensor in the diesel particulate filter is replaced (DPF).
- With every injector change.
- Every time the ECM is replaced.
- In each case of soot accumulation in excess of the maximum allowable value (48 g) and the resulting reduction in power. As a result, normal regeneration is suppressed and DTC P2463 is stored in memory.
- Whenever there is an accumulation of soot in the range of 24 to 48 grams and the following DTCs are stored in the memory. In such cases, regeneration is required, carried out at the service center after the appropriate repair or replacement is performed for each of the DTCs.
- With every injector change.
- With each change in the position of the nozzles.
- Every time the ECM is replaced.
When performing a service regeneration, the exhaust pipe outlet temperature will exceed 550°C (1022°F). It is necessary that no one is near the exhaust pipe.
Place the car on an open and fireproof surface.
Improper application of the service regeneration mode can result in damage to the engine and exhaust system.
Do not perform service regeneration of the particulate filter if the vehicle has malfunctions that are not related to the particulate filter. Using the service regeneration mode with faulty engine components can damage the engine and exhaust system.
Before performing a service regeneration, make sure that no soot is coming from the end of the particulate filter. First, make sure there is no soot near the exhaust pipe. If there is soot, then inspect the exhaust pipe of the particulate filter. The presence of soot at the rear end of the cross section of the particulate filter means that its filtering ability has deteriorated dramatically. If soot comes from the end of the particulate filter, replace the filter.
Check the coolant level before and after the procedure.
After working in service mode, an oil change may be required. The oil viscosity will decrease after each service regeneration. There is a well-known rule of thumb that it is recommended to change the engine oil after a service regeneration if 80% of the planned period of time between oil changes has elapsed. In addition, if more than 3 service regenerations are carried out consecutively, the engine oil must be changed regardless of the remaining oil life.
After service regeneration, the vehicle must cool down. It is advisable to increase the engine speed to 1500 rpm so that the cooling of the exhaust system occurs more evenly and excessive heat generation can be avoided.