Contents: Diagnostic information ↧ Procedure for determining idle speed… ↧ Checking the diagnostic system ↧ ECU output diagnostics ↧ Several fault codes have been set… ↧ The crankshaft turns but the engine… ↧ Malfunction Indicator Lamp (MIL) Not… ↧ Malfunction Indicator Lamp (MIL) is… ↧
Diagnostic information
If an intermittent problem is detected, follow the instructions below.
Preliminary checks
Before using this section, you must first complete "Checking the diagnostic system."
First, perform a thorough inspection. This inspection can often correct the problem without further testing and save valuable time. Check the following:
- The ECM ground is clean, properly tightened, and in the correct location.
- Vacuum hoses must be free of cracks, kinks, in good condition and connected in accordance with the emission control system label. Carefully check the hoses for leaks and blockages.
- Air leak in the throttle body mounting area and intake manifold sealing surfaces.
- Check ignition wires for cracks, hardness, proper routing and leakage current.
- Correct wiring connection.
- Wiring on clamps or cuts.
Diagnostic Trouble Code Table
Do not use the Diagnostic Trouble Code (DTC) chart to troubleshoot intermittent faults. The fault must be present to determine its location.
Incorrect use of the DTC chart may result in unnecessary part replacement.
Faulty wiring or connections
Most intermittent faults are caused by faulty wiring or connections. Carefully check suspect circuits for the following faults:
- Poor contact in the connectors.
- The terminals do not fit tightly into the connector housing.
- Deformed or damaged terminals. All connector terminals in faulty circuits must be carefully checked, repaired or replaced to ensure reliable contact.
- Poor connection of terminals to wires. Requires removal of terminal from connector body.
Sea trial
If the inspection does not reveal the cause of the problem, a road test can be performed with a voltmeter or scan tool connected to the suspect circuit. An abnormal signal level or abnormal reading on the scan tool indicates a problem in that circuit.
If there are no faults in the wires or connectors and a diagnostic trouble code is stored for the circuit that contains the sensor, the sensor must be replaced.
Engine power supply system
Some erratic handling problems may be due to poor fuel quality. If the car is occasionally jerky, stalls, or has other problems, ask the customer how he or she is fueling the car.
- Does he always fill up his car at the same gas station? In this case, fuel problems can be ignored.
- Does he fill up his car at the station that offers the lowest prices? If so, check the fuel tank for deposits, water, or other contaminants.
Procedure for determining idle speed parameters
The following procedure must be performed to determine the idle speed parameters when any one or more of the following actions are performed:
- Replacement with a new ECU controller
- Replacing a new throttle body (MTIA, ETC)
- Replacement with a new IAC valve
- Cleaning the throttle body from carbon deposits
- Disconnecting from power source (battery cable, ECM fuse, etc.) (Delphi ECM only)
1. Turn on the ignition.
2. Reset the adaptation values using a scanning device. (Only with main throttle valve idle speed control drive, engine coolant sensor.)
3. Turn off the ignition for 15 seconds.
4. Turn on the ignition for 5 seconds.
5. Turn off the ignition for 15 seconds. (For the Siemens D160 ECU controller with the ETC system, turn off the ignition for 35 seconds.)
6. Start the engine in Park/Neutral position.
7. If the vehicle is equipped with an automatic transmission, apply the parking brake. With the brake pedal depressed, shift the transmission to position D (drive) for 1 second and return it back to position P (park). (Only Siemens ECU controller).
8. Run the engine until the coolant temperature rises above 85°C (185°F).
9. Turn on the air conditioner for 10 seconds, if available.
10. If the vehicle is equipped with an automatic transmission, apply the parking brake. Depress the brake pedal and set the transmission to position D (drive) for 10 seconds.
11. Turn off the air conditioner for 10 seconds, if available.
12. If the vehicle is equipped with an automatic transmission, depress the brake pedal and shift the transmission into the park/neutral position.
13. Turn off the ignition. The procedure for determining the idle parameters is complete.
14. Wait 15 seconds before restarting the engine (only for Siemens ECU controller). (For the Siemens D160 ECU controller with the ETC system, turn off the ignition for 35 seconds.)
Checking the diagnostic system
Description of the scheme
The Diagnostic System Check is the starting point for any diagnosis of a vehicle's drivability issues. Before performing this procedure, perform a check/inspection of the ECM and engine ground for cleanliness and tightness.
The diagnostic system check is a proven method for identifying problems caused by a malfunction of the electronic engine management system.
Diagnostic information
An intermittent fault may be caused by a poor connection, rubbed insulation, or a broken wire under the insulation. Check for poor connections or damaged wiring harnesses. Check the ECM wiring harness and connections for poor connections, faulty locks, deformed or damaged terminals, poor terminal-to-wire connections, and damaged harnesses.
Description of the test
The numbers below refer to the operation number in the diagnostic table:
1. The malfunction indicator lamp should be constantly illuminated with the ignition on and the engine stopped. If not, go to the Diagnostic Information item.
2. This test examines the Class 2 data circuit and the ability of the ECM to communicate serial data.
3. This tests the ability of the ECM to control the MIL and the absence of a short to ground in the MIL circuit.
4. If the engine does not start, see item "The crankshaft turns, but the engine does not start" in this section.
7. A scan tool parameter outside of the typical range helps to identify the area causing the problem.
10. This vehicle is equipped with an ECM that uses an Electrically Erasable Programmable Read Only Memory (EEPROM). The replacement ECM must be programmed. Reprogramming the ECM is described in the latest Techline.
Checking the diagnostic system
| Step | Operation | Values | Yes | No |
| 1 |
Is the malfunction indicator lamp on?
|
-
|
Jump to operations 2
|
|
| 2 |
Does the scan tool output ECM engine data?
|
-
|
Jump to operations 3
|
Jump to operations 8
|
| 3 |
Is the malfunction indicator lamp off?
|
-
|
Jump to operations 4
|
|
| 4 |
Try to start the engine.
Does the engine start and continue to run?
|
-
|
Jump to operations 5
|
|
| 5 |
Select DISPLAY DTC with the scanning tool.
Are any diagnostic trouble codes stored?
|
-
|
Jump to operations 6
|
Jump to operations 7
|
| 6 |
Check the display for diagnostic trouble codes P0107, P0108, P0113, P0118, P0122, P0123.
Are two or more of the following diagnostic trouble codes stored?
|
-
|
Jump to the appropriate diagnostic trouble code table
|
|
| 7 |
Compare the ECM data values on the scan tool display with typical engine data.
Are the values displayed normal or close to normal?
|
-
|
Go to section "ECU controller output diagnostics"
|
Go to the specified component check
|
| 8 |
Problem found?
|
-
|
Jump to operations 9
|
Jump to operations 10
|
| 9 |
Repair open circuit, short to ground, or short to power in the serial data circuit or in the DLC ignition current circuit.
Is the renovation finished?
|
-
|
The system is normal
|
-
|
| 10 |
Does the scan tool output ECM engine data?
|
-
|
Jump to operations 2
|
Jump to operations 11
|
| 11 |
Replace the ECM.
Is the replacement complete?
|
-
|
The system is normal
|
-
|
ECU output diagnostics
Description of the scheme
The Engine Management System (EMS) controller controls the operation of most of the electronic switch components that make up the grounded circuit when turned on. These switches are arranged in groups of 4 and 7 and are called either a surface-mounted quad control module, which controls up to 4 outputs, or an output control module (ODM), which independently controls up to 7 outputs. Not all outputs are used all the time.
Control modules are protected against short circuits. If a relay or solenoid shorts out, due to very low or zero resistance, or if the control portion of the circuit breaks down, too much current can be supplied to the ECM. The control module reacts to this and the output signal is either turned off or its internal resistance increases, limiting the current and protecting the ECM and control module. As a result, a high output voltage is established at the terminals instead of the required low voltage. If there is an open circuit in the circuit from the + battery to this component or in the component itself, or if the control portion of the circuit shorts to ground, the voltage at the terminals decreases. Any of these conditions is considered a failure in the control module.
The control modules also have a circuit that indicates a voltage drop in the ECM CPU. The scan tool displays the status of the fault circuits in the control modules as 0=normal and 1=fail.
Diagnostic information
The scan tool is capable of controlling the on/off of some components and functions. If a component or function does not support this, operate the vehicle under normal operating conditions to determine if there is an open or short circuit.
An open or short to ground indication appears in the open positions on the scan tool only when it is not controlled by the ECM or scan tool, and a short to voltage is detected in the closed positions on the scan tool only when the component is controlled by the ECM or scan tool.
ECU output diagnostics
| Step | Operation | Values | Yes | No |
| 1 |
Conduct a diagnostic system check.
Is the verification complete?
|
-
|
Jump to operations 2
|
|
| 2 |
Connect the diagnostic tool.
Is there a Data Link Connector (DLC) number 1 (=malfunction) under any of the numbered positions in the OUTPUT CONTROL MODULES?
|
-
|
Jump to operations 3
|
Jump to operations 4
|
| 3 |
Check for an open or short circuit in any of the corresponding positions (circuits) where the number 1 appears and repair is required.
Is the renovation finished?
|
-
|
Jump to operations 9
|
Jump to operations 7
|
| 4 |
Monitor the output signal being tested with a scanning instrument, observing the corresponding position of each circuit.
Did any of the positions change to 1?
|
-
|
Jump to operations 6
|
Jump to operations 5
|
| 5 |
Monitor the output signal being tested with a scanning instrument, observing the corresponding position of each circuit.
Under such control, does the component or function operate?
|
-
|
Jump to operations 9
|
For repair, go to the corresponding component table
|
| 6 |
Correct the short to voltage in the appropriate circuit for the position (circuit) marked with number 1.
Is the renovation finished?
|
-
|
Jump to operations 9
|
-
|
| 7 |
Disconnect the electrical connector from the component connected to the faulty circuit.
1 is still displayed in the corresponding position of the OUTPUT CONTROL MODULE?
|
-
|
Jump to operations 8
|
For repair, go to the corresponding component table
|
| 8 |
Replace the ECM.
Is the replacement complete?
|
-
|
Jump to operations 9
|
-
|
| 9 |
Set the vehicle to the operating conditions in which it was originally noted.
Is the system functioning normally now?
|
-
|
The system is normal
|
Jump to operations 2
|
Several fault codes have been set for the ECM sensors
Description of the scheme
The engine control module (ECM) monitors various sensors to determine engine operating conditions. The ECM controls fuel delivery, spark advance, transmission operation, and emission control system operation based on input signals from the sensors.
The ECM provides ground for all sensors. The ECM supplies 5 volts through a pull-up resistor and monitors the voltage between the sensor and the resistor to determine the status of the coolant temperature (ECT) sensor and the intake air temperature (IAT) sensor. The ECM supplies a 5 volt reference signal and a sensor ground signal to the EGR needle position sensor, throttle position sensor, and manifold absolute pressure sensor. The ECM monitors the individual return signals from these sensors to determine their operating status.
Diagnostic information
Be sure to check the cleanliness and reliability of the ECM controller mount and the engine ground connection.
A short to voltage in one of the sensor circuits may cause one or more high signal/input diagnostic trouble codes to set.
If the sensor input circuit is shorted to the power supply, check that the sensor is not damaged. A faulty sensor will show a high or low signal level after the fault in the corresponding circuit is corrected. If the sensor is damaged, replace it.
An open in one of the sensor circuits will cause one or more low signal/input diagnostic trouble codes to set.
A short to ground in one of the sensor circuits will cause one or more low signal/input diagnostic trouble codes to set.
Check the following:
- Check the ECM for loose connections. Check the wire harness connectors for loose terminal connections, poor contact, faulty locks, deformed or damaged terminals, and loose terminal-to-wire connections.
- Inspect the wiring harness for damage. If the wiring harness appears to be OK, note the corresponding sensor display on the scan tool with the ignition on and the engine off while moving the connectors and wiring harnesses associated with the corresponding sensors. Changes in the corresponding sensor display will indicate the location of the fault.
Several fault codes have been set for the ECM sensors
| Step | Operation | Values | Yes | No |
| 1 |
Conduct a diagnostic system check.
Is the check complete?
|
-
|
Jump to operations 2
|
Go to item "Checking the diagnostic system".
|
| 2 |
Problem found?
|
-
|
Jump to operations 17
|
Jump to operations 3
|
| 3 |
Problem found?
|
-
|
Jump to operations 17
|
Jump to operations 4
|
| 4 |
Measure the voltage of the signal circuit of the exhaust gas recirculation valve needle position sensor (EGR) between the ECM controller wiring harness connector and the ground.
Is the measured voltage close to the specified value?
|
0 B
|
Jump to operations 5
|
Jump to operations 9
|
| 5 |
Measure the voltage of the manifold absolute pressure (MAP) sensor signal circuit between the ECM harness connector and ground.
Is the measured voltage close to the specified value?
|
0 B
|
Jump to operations 6
|
Jump to operations 11
|
| 6 |
Measure the voltage of the throttle position (TP) sensor signal circuit between the ECM harness connector and ground.
Is the measured voltage close to the specified value?
|
0 B
|
Jump to operations 7
|
Jump to operations 12
|
| 7 |
Measure the voltage of the intake air temperature (IAT) sensor signal circuit between the ECM harness connector and ground.
Is the measured voltage close to the specified value?
|
0 B
|
Jump to operations 8
|
Jump to operations 13
|
| 8 |
Measure the voltage of the coolant temperature (ECT) sensor signal circuit between the ECM harness connector and ground.
Is the measured voltage close to the specified value?
|
0 B
|
Jump to operations 16
|
Jump to operations 14
|
| 9 |
Is the measured voltage close to the specified value?
|
0 B
|
Jump to operations 10
|
Jump to operations 15
|
| 10 |
Replace the EGR valve.
Is the renovation finished?
|
-
|
Jump to operations 17
|
-
|
| 11 |
Locate and repair short to power in the MAP sensor signal circuit.
Is the renovation finished?
|
-
|
Jump to operations 17
|
-
|
| 12 |
Locate and repair short to power in the TP sensor signal circuit.
Is the renovation finished?
|
-
|
Jump to operations 17
|
-
|
| 13 |
Locate and repair short to power in the IAT sensor signal circuit.
Is the renovation finished?
|
-
|
Jump to operations 17
|
-
|
| 14 |
Locate and repair short to power in the ECT sensor signal circuit.
Is the renovation finished?
|
-
|
Jump to operations 17
|
-
|
| 15 |
Locate and repair short to power in the EGR valve needle position sensor signal circuit.
Is the renovation finished?
|
-
|
Jump to operations 17
|
-
|
| 16 |
Replace the ECM.
Is the renovation finished?
|
-
|
Jump to operations 17
|
-
|
| 17 |
Does the scan tool report this diagnostic as passed and successful?
|
-
|
Jump to operations 18
|
Jump to operations 2
|
| 18 |
Check to see if any additional diagnostic trouble codes are set.
Are there any diagnostic trouble codes displayed that have not been diagnosed?
|
-
|
Go to the section "Applicable Diagnostic Trouble Codes Table"
|
The system is normal
|
The crankshaft turns but the engine does not start
Description of the test
The sequence corresponds to the steps indicated in the diagnostic table.
1. The diagnostic system check prompts the technician to perform basic checks and save the status and fault data to the scan tool. This creates an electronic copy of the data recorded when the fault occurred. The information is stored in the scan tool for further processing.
1. The diagnostic system check prompts the technician to perform basic checks and save the status and fault data to the scan tool. This creates an electronic copy of the data recorded when the fault occurred. The information is stored in the scan tool for further processing.
3. By performing a compression test, it can be determined whether the engine is mechanically capable of running.
2. By performing a compression test, it can be determined whether the engine is mechanically capable of running.
9. It is important to check for spark on all ignition wires. If there is spark on one to three terminals of the ignition coil, then the crankshaft position sensor (CPS) is normal.
3. It is important to check for spark on all ignition wires. If there is spark on one to three terminals of the ignition coil, then the crankshaft position sensor (CPS) is normal.
19. When checking the output signals of the ECM at the moment of ignition, it is recommended to use an oscilloscope to observe the change in signals. When measuring these output signals with a voltmeter, intermittent faults may occur that are not registered by the voltmeter.
35. This operation checks the correct operation of the ECM in the fuel pump circuit.
59. This operation checks the ground signal supplied by the ECM to control the fuel injectors. If there is no ground signal when the engine is cranked and the fuel injector wiring is normal, the ECM is faulty.
The crankshaft turns but the engine does not start
Caution: To avoid electric shock when working with spark plug wires on a running engine, use insulated pliers.
Caution! Do not pinch or bend nylon fuel lines. Faulty fuel lines may cause fuel leakage, resulting in fire and injury.
| Step | Operation | Values | Yes | No |
| 1 |
Conduct a diagnostic system check.
Has the check been carried out?
|
-
|
Jump to operations 2
|
Go to item "Checking the diagnostic system".
|
| 2 |
Checking if diagnostic trouble code P0601 is set.
Is a diagnostic trouble code set?
|
-
|
Jump to the appropriate diagnostic trouble code table
|
Jump to operations 4
|
| 3 |
Turn the engine crankshaft.
Does the engine start and continue to run?
|
-
|
The system is normal
|
Jump to operations 5
|
| 4 |
Conduct a cylinder compression test.
Is the compression in all cylinders equal to or greater than the specified values?
|
689 kPa (100 psi)
|
Jump to operations 8
|
Jump to operations 5
|
| 5 |
Check the timing belt adjustment.
Is the timing belt of the gas distribution mechanism adjusted?
|
-
|
Jump to operations 7
|
Jump to operations 6
|
| 6 |
Adjust or replace timing belt if necessary.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 7 |
Repair internal engine defects if necessary.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 8 |
Check the fuel pump fuse.
Malfunction detected?
|
-
|
Jump to operations 9
|
Jump to operations 10
|
| 9 |
Replace the fuse.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 10 |
Is the throttle position (TP) sensor reading below the specified value?
|
1.0 V
|
Jump to operations 11
|
|
| 11 |
Compare engine coolant temperature (ECT) with intake air temperature (IAT).
Is EST relatively close to IAT?
|
-
|
Jump to operations 12
|
|
| 12 |
Is the MAP sensor reading above the set value and changing as the crankshaft is cranked?
|
4 B
|
Jump to operations 13
|
Jump to operations 14
|
| 13 |
Turn the engine crankshaft.
Does the active crankshaft position counter value increase as the crankshaft is cranked?
|
-
|
Jump to operations 16
|
Jump to operations 18
|
| 14 |
Check scanned data for sequential data.
Serial data lost when cranking?
|
-
|
Jump to operations 15
|
Go to "Checking the MAP sensor output data"
|
| 15 |
Eliminate voltage loss to the controller (ECM) from the ignition switch.
Is the renovation finished?
|
-
|
The system is normal
|
-
|
| 16 |
Check for spark on all ignition wires when turning the engine with the starter.
Is there spark on all ignition wires?
|
-
|
Jump to operations 41
|
Jump to operations 17
|
| 17 |
Is there spark on all ignition wires?
|
30,000 W
|
Jump to operations 3
|
Jump to operations 18
|
| 18 |
Is the measured signal level close to the set value?
|
1.4V (2.5V)*
|
Jump to operations 19
|
Jump to operations 20
|
| 19 |
Measure the signal level between terminals 2 and 3 of the crankshaft position sensor connector.
Is the measured signal close to the set value?
|
1.4V (2.5V)*
|
Jump to operations 26
|
Jump to operations 21
|
| 20 |
Measure the signal level between terminal 1 of the crankshaft position sensor connector and ground.
Is the measured signal level close to the set value?
|
1.4V (2.5V)*
|
Jump to operations 22
|
Jump to operations 23
|
| 21 |
Measure the signal level between terminal 2 of the crankshaft position sensor connector and ground.
Is the measured signal level close to the set value?
|
1.4V (2.5V)*
|
Jump to operations 22
|
Jump to operations 24
|
| 22 |
Check for an open circuit in the wire between terminal 3 of the crankshaft position sensor connector and ground.
Malfunction detected?
|
-
|
Jump to operations 25
|
Jump to operations 40
|
| 23 |
Check for an open circuit or short circuit in the wire between terminal 1 of the crankshaft position sensor connector and terminal 14 of the J2 connector of the ECM controller.
Malfunction detected?
|
-
|
Jump to operations 25
|
Jump to operations 40
|
| 24 |
Check for an open circuit or short circuit in the wire between terminal 2 of the crankshaft position sensor connector and terminal 15 of the J2 connector of the ECM controller.
Malfunction detected?
|
-
|
Jump to operations 25
|
Jump to 40
|
| 25 |
Correct the faulty circuit.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 26 |
Are the signal values close to the set values?
|
1.4 V (2.5 V)* with ignition on, 1.6 V (2.6 V)* when cranking
|
Jump to operations 27
|
Jump to operations 28
|
| 27 |
Measure the signal level at terminal 15 of the J2 connector of the ECM controller by connecting the ECM controller connector.
Are the signal values close to the set values?
|
1.4 V (2.5 V)* with ignition on, 1.6 V (2.6 V)* when cranking
|
Go to operations 29
|
Jump to operations 28
|
| 28 |
Replace the crankshaft position sensor.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 29 |
Is the indicator light on?
|
-
|
Jump to operations 30
|
Go to operations 31
|
| 30 |
Connect the test lamp to the electronic ignition system coil connector and the positive battery cable.
Is the indicator light on?
|
-
|
Jump to operations 34
|
Jump to operations 32
|
| 31 |
Check for an open circuit in the wire between the ignition switch and terminal 1 of the electronic ignition system coil connector.
Malfunction detected?
|
-
|
Jump to operations 33
|
-
|
| 32 |
Check the wire from the electronic ignition system coil to ground for an open circuit.
Malfunction detected?
|
-
|
Jump to operations 2
|
-
|
| 33 |
Is there spark on all ignition wires?
|
-
|
Jump to operations 3
|
Jump to operations 34
|
| 34 |
Does the voltage fluctuate within the set value?
|
0.2-2.0 V
|
Jump to operations 39
|
Jump to operations 37
|
| 35 |
While turning the crankshaft, measure the signal level at terminal 1 of the electronic ignition system coil connector.
Does the voltage fluctuate within the set value?
|
0.2-2.0 V
|
Jump to operations 39
|
Jump to operations 37
|
| 36 |
Check for an open circuit in the wire between terminal 3 of the electronic ignition system coil connector and terminal 35 of the J2 connector of the ECM controller.
Malfunction detected?
|
-
|
Jump to operations 38
|
Jump to operations 40
|
| 37 |
Check for an open circuit in the wire between terminal 1 of the electronic ignition system coil connector and terminal 40 of the J2 connector of the ECM controller.
Malfunction detected?
|
-
|
Jump to operations 38
|
Jump to operations 40
|
| 38 |
Is there spark on all ignition wires?
|
-
|
Jump to operations 3
|
Jump to operations 39
|
| 39 |
Replace the electronic ignition system coil.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 40 |
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 41 |
Is there fuel pressure?
|
-
|
Jump to operations 44
|
Jump to operations 42
|
| 42 |
Is the indicator light on?
|
2 sec.
|
Jump to operations 43
|
Jump to operations 53
|
| 43 |
Replace the fuel pump.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 44 |
Is the fuel pressure within the set value?
|
283-324 kPa (41-47 psi)
|
Jump to operations 48
|
Jump to operations 45
|
| 45 |
Malfunction detected?
|
-
|
Jump to operations 46
|
Jump to operations 47
|
| 46 |
Is there fuel?
|
283-324 kPa (41-47 psi)
|
Jump to operations 3
|
Jump to operations 47
|
| 47 |
Is there fuel?
|
-
|
Jump to operations 50
|
Jump to operations 51
|
| 48 |
Check fuel for contamination.
Is the fuel contaminated?
|
-
|
Jump to operations 49
|
Jump to operations 65
|
| 49 |
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 50 |
Replace the fuel pressure regulator.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 51 |
Malfunction detected?
|
-
|
Jump to operations 52
|
Jump to operations 43
|
| 52 |
Replace fuel pump sensor, fuel tank filter and/or connecting fuel hoses if clogged.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 53 |
Is the indicator light on?
|
2 sec.
|
Jump to operations 54
|
Jump to operations 55
|
| 54 |
Repair open circuit between terminal 5 of fuel pump connector and ground.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 55 |
Is the indicator light on?
|
2 sec.
|
Jump to operations 56
|
Jump to operations 62
|
| 56 |
Is the indicator light on?
|
-
|
Jump to operations 57
|
Jump to operations 61
|
| 57 |
Is the indicator light on?
|
-
|
Jump to operations 58
|
Jump to operations 64
|
| 58 |
Is the renovation finished?
|
-
|
Jump to operations 2
|
-
|
| 59 |
Replace the fuel cut-off switch.
Malfunction detected?
|
-
|
Jump to operations 3
|
-
|
| 60 |
Replace the fuel pump relay.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 61 |
Malfunction detected?
|
-
|
Jump to operations 72
|
-
|
| 62 |
Check for an open circuit in the wire between terminal 85 of the fuel pump relay connector and terminal 51 of the J1 connector of the ECM controller.
Malfunction detected?
|
-
|
Jump to operations 63
|
Jump to operations 40
|
| 63 |
Repair the wire between terminal 85 of the fuel pump relay connector and terminal 51 of the J1 connector of the ECM.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 64 |
Repair the wire between terminal 30 of the fuel pump relay connector and the positive terminal of the battery.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 65 |
Is the indicator light on for all fuel injectors?
|
-
|
Jump to operations 66
|
Jump to operations 69
|
| 66 |
Does the indicator light come on on all fuel injectors?
|
-
|
Jump to operations 67
|
Jump to operations 70
|
| 67 |
Measure the resistance at each fuel injector.
Resistance within the set value (the resistance will increase slightly at higher temperatures)?
|
11.6-12.4 Ohm
|
The system is normal
|
Jump to operations 68
|
| 68 |
Replace all fuel injectors with resistance outside the specified range.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 69 |
Repair open in wire between terminal 1 of fuel injector harness connector and engine harness.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 70 |
Malfunction detected?
|
-
|
Jump to operations 71
|
Jump to operations 73
|
| 71 |
Repair open circuit in fuel injector wiring harness.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 72 |
Replace the fuse or repair the wiring if necessary.
Is the renovation finished?
|
-
|
Jump to operations 3
|
-
|
| 73 |
Check for open circuit from terminal 1 to each of the four fuel injectors and the ignition switch.
Malfunction detected?
|
-
|
Jump to operations 72
|
-
|
Malfunction Indicator Lamp (MIL) Not Working
Description of the scheme
The fault indicator light must be permanently lit when the ignition switch is turned on and the engine is not running. The system voltage is applied to the indicator lamp, and the instrument panel serves as a conductor for grounding. After starting the engine, the instrument panel turns off the fault indicator light. If there is a failure in the engine management system, the ECM controller sends a message via the high-speed GMLAN network to the body control module with a request for a fault indicator light. The body control module then sends a message to the dashboard via the low-speed GMLAN network requesting that the fault indicator light is turned on.
Description of the test
The number below refers to the stage number from the diagnostic chart.
2. If other functions of the instrument panel are impaired, it is necessary to check the fuse or the presence of voltage supplied to the instrument panel and its grounding.
Malfunction Indicator Lamp (MIL) Not Working
| Step | Operation | Values | Yes | No |
| 1 |
Try to start the engine.
Does the engine start?
|
-
|
Jump to operations 2
|
Go to item "Checking the diagnostic system".
|
| 2 |
Check the operation of the entire instrument panel.
Are all other dashboard functions working properly?
|
-
|
Jump to operations 3
|
|
| 3 |
Replace the instrument panel.
Has the replacement been made?
|
-
|
Jump to operations 4
|
-
|
| 4 |
Turn on the system to check the repair results.
Has the problem been resolved?
|
-
|
The system is normal
|
Jump to operations 2
|
Malfunction Indicator Lamp (MIL) is on continuously
Description of the scheme
The fault indicator light must be permanently lit when the ignition switch is turned on and the engine is not running. The system voltage is applied to the indicator lamp, and the instrument panel serves as a conductor for grounding. After starting the engine, the instrument panel turns off the fault indicator light. If there is a failure in the engine management system, the ECM controller sends a message via the high-speed GMLAN network to the body control module with a request for a fault indicator light. The body control module then sends a message to the dashboard via the low-speed GMLAN network requesting that the fault indicator light is turned on.
Diagnostic information
If the fault indicator light is always on and the transmission diagnostic trouble codes are not set, a deviation has occurred in the serial data transmission circuits.
Malfunction Indicator Lamp (MIL) is on continuously
| Step | Operation | Values | Yes | No |
| 1 |
Have you performed a diagnostic system check?
Is the check complete?
|
-
|
Go to item "Checking the diagnostic system".
|
[The article is based on data from the website ChevyMan.ru]