P1078

DTC P1078: IMT Valve Stuck in Low RPM Position (2004 - 2005 models)

NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information.

1. Turn the ignition switch ON (II).
2. Clear the DTC with the HDS.
3. Start the engine and hold the engine speed above 4,000 rpm.
4. Check the IMT VALVE CMD in the DATA LIST with the HDS.

Is OPEN indicated?

YES - Go to step 5.

NO - Go to step 38.

5. Check the IMT VALVE SW in the DATA LIST with the HDS.

Is CLOSE indicated?

YES - Go to step 6.

NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the IMT actuator and the ECM/PCM.

6. Let the engine idle, then turn the ignition switch OFF.
7. Disconnect the IMT actuator 5P connector.
8. Turn the ignition switch ON (II).




9. Measure voltage between IMT actuator 5P connector terminal No.1 and body ground.

Is there about 5 V?

YES - Go to step 10.

NO - Repair open in the wire between the ECM/PCM (D12) and the IMT actuator, then go to step 27.




10. Measure voltage between IMT actuator 5P connector terminal No.3 and body ground.

Is there about 5 V?

YES - Go to step 11.

NO - Go to step 16.

11. Turn the ignition switch OFF.
12. Jump the SCS line with the HDS.
13. Disconnect ECM/PCM connector D (17P).




14. Connect IMT actuator 5P connector terminal No.2 to body ground with a jumper wire.




15. Check for continuity between ECM/PCM connector terminal D10 and body ground.

Is there continuity?

YES - Go to step 21.

NO - Repair open in the wire between the ECM/PCM (D10) and the IMT actuator, then go to step 29.

16. Turn the ignition switch OFF.
17. Jump the SCS line with the HDS.
18. Disconnect ECM/PCM connector B (24P).




19. Connect IMT actuator 5P connector terminal No.3 to body ground with a jumper wire.




20. Check for continuity between ECM/PCM connector terminal B11 and body ground.

Is there continuity?

YES - Go to step 36.

NO - Repair open in the wire between the ECM/PCM (B11) and the IMT actuator, then go to step 29.




21. Check for continuity between ECM/PCM connector terminal B4 and body ground.

Is there continuity?

YES - Repair short in the wire between the ECM/PCM (B4) and the IMT actuator, then go to step 29.

NO - Go to step 22.




22. Connect IMT actuator 5P connector terminal No.5 to body ground with a jumper wire.




23. Check for continuity between ECM/PCM connector terminal B4 and body ground.

Is there continuity?

YES - Go to step 24.

NO - Repair open in the wire between the ECM/PCM (B4) and the IMT actuator, then go to step 29.




24. Check for continuity between ECM/PCM connector terminal B3 and body ground.

Is there continuity?

YES - Repair short in the wire between the ECM/PCM (B3) and the IMT actuator, then go to step 29.

NO - Go to step 25.




25. Connect IMT actuator 5P connector terminal No.4 to body ground with a jumper wire.




26. Check for continuity between ECM/PCM connector terminal B3 and body ground.

Is there continuity?

YES - Go to step 27.

NO - Repair open in the wire between the ECM/PCM (B3) and the IMT actuator, go to step 29.

27. Remove the IMT actuator.
28. Move the IMT valve by hand.

Does it move smoothly?

YES - Substitute a known-good IMT actuator, then go to step 29 and recheck. If DTC P1078 is not indicated, replace the IMT actuator, then go to step 29. If DTC P1078 is indicated, go to step 36.

NO - Remove the intake manifold cover, and repair the stuck valve. If necessary, replace the intake manifold, then go to step 29.

29. Reconnect all connectors.
30. Turn the ignition switch ON (II).
31. Reset the ECM/PCM with the HDS.
32. Do the ECM/PCM idle learn procedure.
33. Start the engine. Hold the engine speed at 4,000 rpm for 10 seconds, then let it idle.
34. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES - If DTC P1078 is indicated, check for poor connections or loose terminals at the IMT actuator and the ECM/PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.

NO - Go to step 35.

35. Monitor the OBD STATUS for DTC P1078 in the DTCs MENU with the HDS.

Does the screen indicate PASSED?

YES - Troubleshooting is complete.

NO - If the screen indicates FAILED, check for poor connections or loose terminals at the IMT actuator and the ECM/PCM, then go to step 1. If the screen indicates NOT COMPLETED, go to step 32 and recheck.

36. Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM.
37. Start the engine. Hold the engine speed at 4,000 rpm for 10 seconds, then let it idle.
38. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES - If DTC P1078is indicated, check for poor connections or loose terminals at the IMT actuator and the ECM/PCM, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.

NO - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM.