Important Preliminary Checks
Before using this section, you must "Diagnostic system check", described in this section and check if all of the following conditions are met:
- The ECM and MIL are working properly.
- No diagnostic trouble codes in memory (DTC).
- The scan tool data is within the normal operating range.
- Check customer complaints and correctly identify the symptoms of the problem. Check everything listed for this symptom.
- Certain indication procedures require a thorough visual/physical inspection. This step is extremely important and can allow you to fix the problem without further checks and save time.
- Verify that the following non-factory-installed options are installed correctly:
- Lighting
- Cellular telephone
- Remote engine start system
- Burglar alarm not installed by the manufacturer
Visual and physical examination
Check the following:
- Make sure the controller is connected to "mass" clean, securely tightened and properly positioned.
- Check the vacuum hoses for integrity, the absence of knots and the reliability of the connection.
- Check wiring:
- Correct connections.
- Clamping
- notches
The table below contains groups of possible causes for each symptom. The order in which these procedures are performed does not matter. If the scan tool reading does not indicate a problem, then proceed in a logical sequence, starting with the most easily performed checks or the most likely causes.
Checking customer complaints
Select the table for the corresponding symptom. Carry out the checks indicated for the present symptom from the following symptom tables:
- Intermittent faults
- Difficult start
- Pops / shots in the silencer
- Lack of power and throttle response, soft pedal effect
- Detonation / combustion noise
- Delays, dips, jerks
- Interruptions in the engine; Delays, failures
- High fuel consumption
- Rough, erratic or incorrect idling or engine stall
- Excessive exhaust smoke
Intermittent faults
sightseeing
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operation, action
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Definition: The fault is currently not present, but is contained in the DTC archive.
Definition: OR
Definition: There is a customer complaint, but the problem cannot be reproduced at this time if it is not related to the DTC.
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Preliminary
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visual / physical
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This step can be important to identify the problem without extensive testing. Perform a thorough visual and physical inspection of the following components.
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Harness/Connector Check
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Many intermittent open or short circuits come and go due to the movement of harnesses and connectors caused by vibration, engine torque, bumps and uneven road surfaces, etc. Check if this type of malfunction occurs by following the procedure below:
If the movement of the harness or connector affects the data displayed on the display, the operation of components and systems, or the engine, inspect the harnesses and connectors and make the necessary repairs.
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Electrical connections and wiring
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Most intermittent faults are due to poor electrical connections, poor mechanical connection of connector pins, or wiring errors. Thoroughly check suspicious circuits for the following faults:
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Power supply and connections to "mass" controller
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Faulty electrical connections or connections to "mass" can cause a variety of symptoms to appear.
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Temperature sensitivity
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Electromagnetic Interference and Electromagnetic Noise
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Some electrical components and circuits are sensitive to electromagnetic interference or other types of electrical noise. Check the following:
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Incorrect controller programming
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Important: It is NOT ALLOWED to reprogram the controller using OLD software / calibration files that are already in the controller. This troubleshooting method is not effective for all types of drivability problems.
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Reproducing Fault Conditions
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If previous tests were unsuccessful, then try to reproduce and (or) fix the conditions for the occurrence of a malfunction. The status/fault log data contains, where appropriate, the conditions under which the DTC was set.
The second possible way is to perform a trip by connecting a digital multimeter to the suspicious circuit. An abnormal multimeter reading when a problem occurs can help determine the cause.
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Scanning tool operation in mode "snapshot"
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The scan tool can be switched to "snapshot" parameters coming through the serial data link. In mode "snapshot" the current data is recorded for a certain period of time. Recorded data can be viewed and analyzed. In addition, the scanning tool can generate graphs for individual parameters, as well as for a group, for comparison purposes. Mode "snapshot" can be turned on manually when a malfunction is detected, or pre-selected to turn on when a DTC is set.
Any deviation from the norm, recorded in the recorded data, may allow you to determine the system or component that should be checked. More information about the mode "snapshot" refer to the operating instructions for the scanning instrument.
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Difficult start
sightseeing
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operation, action
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Definition: The engine cranks normally, but the engine does not start for a long time. The engine will eventually start, or may start but stall immediately.
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Preview
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Sensor test
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Fuel system check
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Checking the electrical system
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Check the speed of rotation of the crankshaft when starting the engine.
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Checking the air intake system
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Check of system of release of the fulfilled gases
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Check the exhaust system, which should not be obstructed by the passage of gases.
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Checking the mechanical part of the engine
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Inspect the engine, checking for the following faults:
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Additional checks
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Pops / shots in the silencer
sightseeing
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operation, action
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Definition: Engine power fluctuates at constant throttle position or constant speed The vehicle accelerates and decelerates without changing the accelerator position.
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Preview
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Sensor test
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Fuel system check
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Additional checks
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Lack of power and throttle response, soft pedal effect
sightseeing
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operation, action
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Definition: The engine develops less power than expected. The vehicle accelerates little or no acceleration when the accelerator pedal is depressed partially.
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Preview
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Sensor test
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Fuel system check
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Exhaust System Checks
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Air Intake System Checks
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Checking the mechanical part of the engine
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Check if the engine has the following faults:
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Additional checks
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Detonation / combustion noise
sightseeing
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operation, action
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Definition: Light or hard knocking, usually worse with acceleration. The engine produces sharp metallic knocks that change when the accelerator pedal is depressed.
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Preliminary checks
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Cooling System Checks
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Sensor test
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Fuel system checks
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Engine Mechanical Checks
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Additional checks
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Delays, dips, jerks
sightseeing
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operation, action
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Definition: After depressing the accelerator pedal, there is no reaction from the engine for a short time. This fault can occur at any vehicle speed. Typically, the malfunction manifests itself most noticeably when starting the car from a place. With a sufficiently noticeable manifestation of a malfunction, the engine may stall.
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Preview
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Fuel system check
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Sensor test
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Additional checks
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Interruptions in the engine; Delays, failures
sightseeing
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operation, action
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Definition: Constant jerking that accompanies engine operation, usually more noticeable with increasing engine load, usually not felt at speeds above 1500 rpm or 48 km/h (30 mph). Exhaust gases make a constant hissing sound at idle, at low speeds or at high acceleration due to insufficient fuel supply, which can cause the engine to stop working.
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Preview
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Sensor test
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Checking the mechanical part of the engine
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Fuel system check
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High fuel consumption
sightseeing
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operation, action
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Definition: Fuel consumption, measured in real road tests and with several fillings of the fuel tank, is noticeably higher than expected. Also, fuel consumption is significantly higher than that measured in previous road tests of this vehicle.
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Preview
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Sensor test
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Fuel system check
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Checking the cooling system
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Additional checks
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Rough, erratic idling or incorrect idle speed and engine stall
sightseeing
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operation, action
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Definition: Engine idles unevenly. With a noticeable manifestation of a malfunction, shaking of the engine or car is possible. The idle speed may vary. Any of these malfunctions, if noticeable, may be enough to stop the engine.
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Preview
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Sensor test
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Fuel system check
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Checking the mechanical part of the engine
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Additional checks
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Excessive exhaust smoke (gray or blue)
sightseeing
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operation, action
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Definition: Gray or blue exhaust smoke under load, at idle, or when starting a hot or cold engine.
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Preview
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Fuel system check
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Sensor test
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Checking the air intake system
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Checking the mechanical part of the engine
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Turbocharger check
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Check for leaks at the turbocharger seals.
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Excessive exhaust smoke (white)
sightseeing
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operation, action
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Definition: White exhaust smoke under load, at idle, or when starting a hot or cold engine.
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Preview
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Fuel system check
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Sensor test
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Checking the air intake system
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Checking the mechanical part of the engine
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Excessive exhaust smoke (black)
sightseeing
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operation, action
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Definition: Black exhaust smoke under load, at idle, or when starting a hot or cold engine.
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Preview
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Fuel system check
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Sensor test
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Checking the air intake system
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Checking the mechanical part of the engine
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Malfunction indicator lamp (MIL) does not burn
Circuit Description
The Malfunction Indicator Lamp (MIL) should be constantly lit when the ignition switch is in the ON position and the engine is not running. System voltage is applied to the indicator lamp, and the instrument panel serves as a ground conductor. After starting the engine, the instrument panel turns off the malfunction indicator lamp. When a malfunction occurs in the engine management system, the ECM sends a message via high speed GMLAN to the body control module requesting a malfunction indicator lamp. The body control module then sends a message to the instrument cluster via low speed GMLAN requesting that the MIL be turned on.
Description of the test
The number below refers to the stage number from the diagnostic table.
If other functions of the instrument panel are disturbed, it is necessary to check the fuse or the presence of voltage supplied to the instrument panel and its grounding.
Malfunction indicator lamp (MIL) does not burn
Step | Operation | Values | Yes | No |
1 |
Have you performed a diagnostic system check?
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-
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Go to operation 2
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Go to item "Diagnostic system check".
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2 |
Check the operation of the entire dashboard.
Are all other dashboard functions OK?
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-
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Go to operation 3
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3 |
Replace dashboard.
Has the replacement been made?
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-
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Go to operation 4
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-
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4 |
Turn on the system to check the repair results.
Has the problem been resolved?
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-
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System OK
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Go to operation 2
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