2000 - 2999: 2624
2624 CHARGE AIR SYSTEM OFFSET DRIFT UNDER ENGINE LOAD
For a complete wiring diagram Refer to the Wiring Information Electrical Diagrams
1. DTC IS ACTIVE
1. Ignition on, engine not running.
2. With the scan tool, Clear DTCs in the Engine Control Module (ECM).
3. Attempt to start the engine and test drive the vehicle.
4. With the scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go To 2
No
- Refer to the *CHECKING FOR AN INTERMITTENT DTC Diagnostic Procedure.
2. INTAKE AIR SYSTEM LEAK
1. Turn the ignition off.
2. Inspect intake air system for leaks and restrictions.
3. Inspect sealing surfaces around the hot film Mass Air Flow Sensor and the Intake Air Temperature Sensor.
4. Verify the Air Cleaner is sealed properly.
Were any leaks found?
Yes
- Repair as necessary.
- Perform the ECM Verification Test. Verification Tests
No
- Go To 3
3. INTAKE AIR TEMPERATURE ACTUAL VALUE
1. Turn the ignition on.
2. With the scan tool, verify the Boost Air temperature is greater than 12.3° C (52° F).
3. Disconnect the Intake Air Temperature Sensor harness connector.
4. Turn the ignition on.
5. With the scan tool monitor the Intake Air Temperature Sensor value.
Is the Intake Air Temperature Sensor approximately -40° C?
Yes
- Go To 8
No
- Go To 4
4. INTAKE AIR TEMPERATURE CIRCUIT CHECK
1. Measure the voltage between the IAT Sensor Signal circuit and the IAT Sensor ground circuit at the IAT Sensor harness connector.
Is the voltage between 4.6 and 5.1 volts?
Yes
- Replace the Intake Air Temperature Sensor.
- Perform the ECM Verification Test. Verification Tests
No
- Go To 5
5. IAT SIGNAL CIRCUIT OPEN
1. Turn the ignition off.
2. Disconnect the Engine Control Module (ECM) harness connectors.
3. Measure the resistance in the IAT Signal circuit between the ECM and Sensor harness connectors.
Is the resistance below 5.0 Ohms?
Yes
- Go To 6
No
- Repair the excessive resistance in the IAT Signal circuit.
- Perform the ECM Verification Test. Verification Tests
6. IAT SIGNAL CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the IAT Signal circuit at the IAT Sensor harness connector.
Is the resistance below 100 kOhms?
Yes
- Repair the short to ground in the IAT Signal circuit.
- Perform the ECM Verification Test. Verification Tests
No
- Go To 7
7. IAT SENSOR GROUND CIRCUIT OPEN
1. Measure the resistance in the IAT Sensor ground circuit between the ECM and Sensor harness connectors.
Is the resistance below 5.0 Ohms?
Yes
- Go To 20
No
- Repair the excessive resistance in the IAT Sensor ground circuit.
- Perform the ECM Verification Test.Verification Tests
8. HOT FILM MASS AIR FLOW SENSOR INSPECTION WITH THE ENGINE NOT RUNNING
1. Turn the ignition on.
NOTE: The hot film MAF sensor must have no air flow during this test.
2. Verify battery is fully charged.
3. With the scan tool, monitor the hot film MAF Sensor in microseconds.
Is the HFM-SFI (Cycle duration) between 510 and 560 microseconds?
Yes
- Go To 9
No
- Go To 10
9. HOT FILM MASS AIR FLOW SENSOR INSPECTION WITH THE ENGINE RUNNING
1. Start the engine.
NOTE: Engine RPM must be greater than or equal to 2500 RPM.
2. With the scan tool, monitor the hot film MAF Sensor in microseconds.
Is the HFM-SFI (Cycle duration) between 150 and 450 microseconds?
Yes
- Go To 16
No
- Go To 10
10. MAF SENSOR IGNITION SWITCH OUTPUT (RUN-START) CIRCUIT OPEN OR HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the hot film MAF Sensor harness connector.
3. Turn the ignition on.
4. Measure the voltage between the Ignition Switch Output (Run-Start) circuit and the ground circuit in the hot film MAF Sensor harness connector.
Is the voltage between 11 and 14 volts?
Yes
- Go To 11
No
- Repair the open or short to ground in the Ignition Switch Output (Run-Start) circuit. Inspect the related fuse.
- Perform the ECM Verification Test. Verification Tests
11. MAF SENSOR SIGNAL CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the MAF Sensor Signal circuit between the hot film Mass Air Flow Sensor harness connector and the Engine Control Module (ECM) harness connector.
Is the resistance below 10.0 Ohms?
Yes
- Go To 12
No
- Repair the excessive resistance in the hot film MAF Sensor Signal circuit.
- Perform the ECM Verification Test. Verification Tests
12. MAF SENSOR GROUND CIRCUIT OPEN OR HIGH RESISTANCE
1. Measure the resistance of the hot film MAF Sensor Ground circuit between the Mass Air Flow Sensor harness connector and the Engine Control Module (ECM) harness connector.
Is the resistance below 10.0 Ohms?
Yes
- Go To 13
No
- Repair the excessive resistance in hot film MAF Sensor Ground circuit
- Perform the ECM Verification Test. Verification Tests
13. MAF SENSOR SIGNAL CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the hot film MAF Sensor Signal circuit in the MAF Sensor harness connector.
Is the resistance above 1000 Ohms?
Yes
- Go To 14
No
- Repair the short to ground in the hot film MAF Sensor Signal circuit.
- Perform the ECM Verification Test. Verification Tests
14. MAF SENSOR SIGNAL CIRCUIT SHORTED TO THE MAF SENSOR GROUND CIRCUIT
1. Measure the resistance between the hot film MAF Sensor Signal circuit and the hot film MAF Sensor Ground circuit in the Mass Air Flow Sensor harness connector.
Is the resistance above 1000 Ohms?
Yes
- Go To 15
No
- Repair the short between the Mass Air Flow Sensor Signal circuit and the Mass Air Flow Sensor Ground circuit.
- Perform the ECM Verification Test. Verification Tests
15. MASS AIR FLOW SENSOR
1. Connect the Engine Control Module (ECM) harness connector.
2. Replace the hot film Mass Air Flow Sensor
3. Turn the ignition on.
4. With the scan tool, Clear DTCs.
5. Start the engine and allow it to reach normal operating temperature.
6. With the scan tool, select View DTCs.
Is the status Active for this DTC?
Yes
- Go To 20
No
- Test Complete.
- Perform the ECM Verification Test. Verification Tests
16. EGR VALVE SOLENOID ACTUATION
1. Start the engine.
2. The engine coolant temp must be greater than 0° C (32° F).
3. The transmission must be in the Neutral position.
4. With the scan tool, Actuate the EGR Valve Solenoid.
NOTE: The air mass will drop when the EGR Valve opens and the air mass will raise when the EGR Valve closes.
Does the air mass value drop when the EGR Valve is opened and does the air mass volume raise when the EGR Valve closes?
Yes
- Look for any chafed, pierced, pinched, or partially broken wires. Look for broken, bent, pushed out or corroded terminals. Repair as necessary.
- Perform the ECM Verification Test. Verification Tests
No
- Go To 17
17. EGR SOLENOID FUSED ASD RELAY OUTPUT CIRCUIT OPEN OR HIGH RESISTANCE
1. Turn the ignition off.
2. Disconnect the EGR Solenoid harness connector.
3. Turn the ignition on.
4. Measure the voltage between the Fused ASD Relay Output circuit and the Ground circuit in the EGR Solenoid harness connector.
Is the voltage between 11 and 14 volts?
Yes
- Go To 18
No
- Repair the open or short to ground in the Fused ASD Relay Output circuit. Inspect the related fuse.
- Perform the ECM Verification Test. Verification Tests
18. EGR SOLENOID CONTROL CIRCUIT OPEN
1. Turn the ignition off.
2. Disconnect the ECM harness connectors.
3. Measure the resistance of the EGR Solenoid Control circuit between the EGR Solenoid harness connector and the Engine Control Module (ECM) harness connector.
Is the resistance below 5.0 Ohms?
Yes
- Go To 19
No
- Repair the excessive resistance in the EGR Solenoid Control circuit
- Perform the ECM Verification Test. Verification Tests
19. EGR SOLENOID CONTROL CIRCUIT SHORTED TO GROUND
1. Measure the resistance between ground and the EGR Solenoid Control circuit at the EGR Solenoid harness connector.
Is the resistance below 100 kOhms?
Yes
- Repair the short to ground in the EGR Solenoid Control circuit
- Perform the ECM Verification Test. Verification Tests
No
- Go To 20
20. ENGINE CONTROL MODULE (ECM)
1. Using the wiring diagram/schematic as a guide, inspect the wiring and connectors between the Intake Air Temperature Sensor, hot film MAF Sensor, EGR Valve Solenoid, and the Engine Control Module (ECM).
2. Look for any chafed, pierced, pinched, or partially broken wires.
3. Look for broken, bent, pushed out or corroded terminals.
4. Monitor the scan tool data relative to this circuit and wiggle test the wiring and connectors.
5. Look for the data to change or for the DTC to reset during the wiggle test.
6. Search for any Technical Service Bulletins that may apply.
Were any problems found?
Yes
- Repair as necessary.
- Perform the ECM Verification Test.Verification Tests
No
- Replace the Engine Control Module (ECM).
- Perform the ECM Verification Test. Verification Tests