INSPECTION AND VERIFICATION
| CAUTION | Diagnosis by substitution from a donor vehicle is NOT acceptable. Substitution of control modules does not guarantee confirmation of a fault, and may also cause additional faults in the vehicle being tested and/or the donor vehicle. |
Note. For diagnostic purposes the cylinders are divided into two banks: Bank 1 - Cylinder numbers 1, 2 and 3. Bank 2 - Cylinders 4, 5 and 6.
- Verify the customer concern.
- Visually inspect for obvious mechanical or electrical faults. VISUAL INSPECTION Mechanical Electrical Engine oil level Cooling system coolant level Fuel level Fuel contamination/grade/quality Throttle body Variable valve timing (VVT) units Fuses Wiring harness Electrical connector(s) Sensor(s) Variable valve timing (VVT) solenoids Engine Control Module (ECM) Transmission Control Module (TCM)
- If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- Use the approved diagnostic system or a scan tool to retrieve any diagnostic trouble codes (DTCs) before moving onto the symptom chart or DTC index. Make sure that all DTCs are cleared following rectification.
SYMPTOM CHART
| Symptom (general) | Symptom (specific) | Possible causes | Action |
|---|---|---|---|
| Non-Start | Engine does not crank | Security system / Immobilizer engaged Engine control module (ECM) relay fault Battery discharged Starting system fault Engine seized | Check that the security system is disarmed. Check the ECM relay operation. Check the battery and starter systems. Refer to the electrical information. Check that the engine turns by hand. |
| Engine cranks, but does not fire | Low/contaminated fuel Ignition system fault Fuel system fault Crankshaft position (CKP) sensor fault Engine control module (ECM) fault | Check the fuel level and condition. Check for DTCs indicating ignition, fuel or sensor faults. Rectify as necessary. Refer to the warranty policy and procedures information if an ECM is suspect. | |
| Engine cranks and fires, but will not start | Evaporative emissions purge valve fault Fuel system fault Spark plugs fouled/incorrect gap Ignition coil fault(s) | Check for DTCs indicating evaporative emissions, fuel or ignition system faults. Rectify as necessary. | |
| Difficult to start | Difficult to start cold | Check coolant anti-freeze content Battery discharged Crankshaft position (CKP) sensor fault Fuel system fault Evaporative emissions purge valve fault | Check the coolant anti-freeze content. Check the battery condition and state of charge. Check for DTCs indicating a sensor, fuel system or evaporative emissions system fault. Rectify as necessary. |
| Difficult to start hot | Injector leak Fuel system fault Fuel temperature sensor fault Intake air temperature (IAT) sensor fault Mass air flow (MAF) sensor fault Evaporative emissions purge valve fault Ignition system fault | Check for DTCs indicating an injector, fuel system or sensor fault. Check the evaporative emission and ignition systems. Rectify as necessary. | |
| Difficult to start after hot soak (vehicle standing after engine has reached operating temperature) | Injector leak Fuel system fault Fuel temperature sensor fault Intake air temperature (IAT) sensor fault Mass air flow (MAF) sensor fault Evaporative emissions purge valve fault Ignition system fault | Check for DTCs indicating an injector, fuel system or sensor fault. Check the evaporative emission and ignition systems. Rectify as necessary. | |
| Engine cranks too fast/slow | Battery discharged Starting system fault Compressions high/low | Check the battery condition and state of charge. Check the starter system. Refer to the electrical information. Check the engine compressions. Rectify as necessary. | |
| Engine stalls | Engine stalls soon after start | Breather system disconnected/restricted Air filter restricted Fuel line fault Engine control module (ECM) relay fault Mass air flow (MAF) sensor fault Ignition system fault | Check the engine breather and intake systems. Check the fuel lines for leakage, etc. Check for DTCs indicating an ECM relay, sensor or ignition system fault. Rectify as necessary. |
| Engine stalls on overrun | Engine control module (ECM) relay fault Throttle position (TP) sensors fault | Check for DTCs indicating an ECM relay or TP sensor fault. Rectify as necessary. | |
| Engine stalls at steady speed | Engine control module (ECM) relay fault Crankshaft position (CKP) sensor fault Throttle position (TP) sensors fault | Check for DTCs indicating an ECM relay or sensor fault. Rectify as necessary. | |
| Engine stalls with speed control enabled | Engine control module (ECM) relay fault | Check for DTCs indicating an ECM relay fault. Rectify as necessary. | |
| Engine stalls when maneuvering | Additional engine loads (power steering, air conditioning (A/C), etc.) Engine control module (ECM) relay fault Throttle position (TP) sensors fault Transmission malfunction Controller area network (CAN) malfunction | Check the accessory drive systems. Check for DTCs indicating an ECM relay, sensor, transmission or CAN fault. Rectify as necessary. | |
| Poor driveability | Engine hesitates/poor acceleration | Fuel line fault Fuel pump fault Injector leak Fuel pressure fault Throttle position (TP) sensors fault Throttle motor fault Ignition system fault Heated oxygen sensor (HO2S) fault Transmission malfunction Restricted accelerator pedal travel (carpet, etc.) Accelerator pedal position (APP) sensor fault | Check the fuel lines and intake air system. Check for DTCs indicating a fuel pump or pressure fault. Check for DTCs indicating a TP sensor or motor fault. Check for DTCs indicating an ignition, sensor or transmission fault. Check the APP sensor for full movement, etc. Rectify as necessary. |
| Engine backfires | Fuel pump fault Fuel line fault Mass air flow (MAF) sensor fault Heated oxygen sensor (HO2S) fault Ignition system fault Sticking variable valve timing (VVT) hub Accelerator pedal position (APP) sensor fault | Check the fuel pump and lines. Check for DTCs indicating a sensor, ignition or VVT fault. Rectify as necessary. | |
| Engine surges | Fuel pump fault Fuel line fault Mass air flow (MAF) sensor fault Throttle position (TP) sensors fault Throttle motor fault Ignition system fault | Check the fuel pump and lines. Check for DTCs indicating a sensor or ignition system fault. Rectify as necessary. | |
| Engine detonates/knocks | Fuel pump fault Fuel line fault Fuel quality Knock sensor (KS) / circuit malfunction Mass air flow (MAF) sensor fault Heated oxygen sensor (HO2S) fault Sticking variable valve timing (VVT) hub Barometric pressure (BARO) sensor malfunction (internal engine control module (ECM) fault) | Check the fuel pump and lines. Check the fuel for contamination and correct grade. Check for DTCs indicating a sensor, VVT or ECM fault. Rectify as necessary. Refer to the warranty policy and procedures information if an ECM is suspect. | |
| No throttle response | Accelerator pedal position (APP) sensor fault Throttle position (TP) sensors fault Throttle motor fault | Check for DTCs indicating a sensor or throttle motor fault. Rectify as necessary. | |
| Speed control inhibited or disabled | Default mode enabled Speed control switch(es) Throttle position (TP) sensors fault Controller area network (CAN) fault | Check the message center for default messages. Check for DTCs indicating a speed control, sensor or CAN fault. Rectify as necessary. | |
| Poor throttle response | Breather system disconnected/restricted Accelerator pedal position (APP) sensor fault Throttle position (TP) sensors fault Engine coolant temperature (ECT) sensor fault Mass air flow (MAF) sensor fault Transmission malfunction | Check the engine breather system. Check for DTCs indicating a sensor or transmission fault. Rectify as necessary. | |
| Engine defaults, warning light and messages. Refer to the owner handbook | Throttle position (TP) sensors fault Mass air flow (MAF) sensor fault Engine coolant temperature (ECT) sensor fault | Check for DTCs indicating a sensor fault. Rectify as necessary. |
DTC INDEX
Note. If a control module or component is suspect and the vehicle remains under manufacturer warranty, refer to the Warranty Policy and Procedures information or determine if any prior approval program is in operation, before the replacement of a component.
Note. Generic scan tools may not read the codes listed, or may read only five digit codes. Match the five digits from the scan tool to the first five digits of the seven digit code listed to identify the fault (the last two digits give additional information read by the manufacturer approved diagnostic system).
Note. When performing voltage or resistance tests, always use a digital multimeter (DMM) accurate to three decimal places, and with an up-to-date calibration certificate. When testing resistance always take the resistance of the DMM leads into account.
Note. Check and rectify basic faults before beginning diagnostic routines involving pinpoint tests.
Note. Inspect connectors for signs of water ingress, and pins for damage and/or corrosion.
Note. If diagnostic trouble codes are recorded and, after performing the pinpoint tests, a fault is not present, an intermittent concern may be the cause. Always check for loose connections and corroded terminals.
For a complete list of all Diagnostic Trouble Codes (DTCs) that could be logged on this vehicle, please refer to General Information. Refer to DIAGNOSTIC TROUBLE CODE (DTC) INDEX - I6 3.2L PETROL, DTC: ENGINE CONTROL MODULE (ECM) .
POWERTRAIN CONTROL MODULE (PCM) LONG DRIVE CYCLE SELF-TEST
| WARNING | Where possible, all road tests should be on well surfaced and dry roads. Always comply with speed limits and local traffic regulations. |
Note. This procedure is an overcheck only. If fault codes are found, interrogation of the relevant system must be carried out and claimed against.
Note. The vehicle must exceed 50mph (80 km/h) during the road test.
- Connect the diagnostic equipment to the vehicle.
- Follow on screen prompts and check for engine management fault codes.
- Clear the fault codes following the on screen procedure.
- Disconnect the diagnostic equipment from the vehicle.
- Carry out a road test and perform the following operations. Accelerate to 55 mph (88 km/h) in 5th gear and cruise for 2 minutes with the engine speed at or above 1800rpm. Lift off the throttle and allow the vehicle to decelerate until the engine speed is less than 1000 rpm. Stop the vehicle. Release brake, allow the vehicle to move with no throttle for 1 minute. Road test is now complete.
- Connect the diagnostic equipment to the vehicle.
- Follow on screen prompts and check for engine management fault codes.
- Disconnect the diagnostic equipment from the vehicle.
POWERTRAIN CONTROL MODULE (PCM) SHORT DRIVE CYCLE SELF-TEST
Note. This procedure is an overcheck only. If fault codes are found, interrogation of the relevant system must be carried out and claimed against.
- Connect the diagnostic equipment to the vehicle.
- Follow on screen prompts and check for engine management fault codes.
- Clear the fault codes following the on screen procedure.
- Start the engine. Allow the engine to idle for 30 seconds. Raise the engine speed to 1500 rpm and hold for 3 minutes until a temperature of 70°C (158 °F) is achieved. Allow the engine to idle for 30 seconds. Switch off the engine.
- Follow on screen prompts and check for engine management fault codes.
- Disconnect the diagnostic equipment from the vehicle.