DTC Troubleshooting

DTC P0641: Sensor Reference Voltage A Malfunction ('05-07 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. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0641 indicated?

YES - Go to step 4.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the ECM/PCM and these connectors:
- MAP sensor
- APP sensor
- IMT(IMRC) actuator
- EGR valve
- FTP sensor
- Input shaft (mainshaft) speed sensor
- Output shaft (countershaft) speed sensor

4. Turn the ignition switch OFF.
5. Disconnect the MAP sensor 3P connector.
6. Turn the ignition switch ON (II).
7. Clear the DTC with the HDS.
8. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0641 indicated?

YES - Go to step 9.

NO - Replace the MAP sensor, then go to step 43.

9. Turn the ignition switch OFF.
10. Disconnect the APP sensor 6P connector.
11. Turn the ignition switch ON (II).
12. Clear the DTC with the HDS.
13. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0641 indicated?

YES - Go to step 14.

NO - Replace the APP sensor, then go to step 43.

14. Turn the ignition switch OFF.
15. Disconnect the IMT (IMRC) actuator 5P connector.
16. Turn the ignition switch ON (II).
17. Clear the DTC with the HDS.
18. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0641 indicated?

YES - Go to step 19.

NO - Replace the IMT (IMRC) actuator, then go to step 43.

19. Turn the ignition switch OFF.
20. Disconnect the EGR valve 6P connector.
21. Turn the ignition switch ON (II).
22. Clear the DTC with the HDS.
23. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0641 indicated?

YES - Go to step 24.

NO - Replace the EGR valve, then go to step 43.

24. Turn the ignition switch OFF.
25. Disconnect the FTP sensor 3P connector.
26. Turn the ignition switch ON (II).
27. Clear the DTC with the HDS.
28. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0641 indicated?

YES - Go to step 29.

NO - Replace the FTP sensor, then go to step 43.

29. Turn the ignition switch OFF.
30. Disconnect the input shaft (mainshaft) speed sensor 3P connector.
31. Turn the ignition switch ON (II).
32. Clear the DTC with the HDS.
33. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0641 indicated?

YES - Go to step 34.

NO - Replace the input shaft (mainshaft) speed sensor, then go to step 43.

34. Turn the ignition switch OFF.
35. Disconnect the output shaft (countershaft) speed sensor 3P connector.
36. Turn the ignition switch ON (II).
37. Clear the DTC with the HDS.
38. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0641 indicated?

YES - Go to step 39.

NO - Replace the output shaft (countershaft) speed sensor, then go to step 43.

39. Turn the ignition switch OFF.
40. Jump the SCS line with the HDS.
41. Disconnect ECM/PCM connectors A (31P) and D(17P).




42. Check for continuity between body ground and ECM/PCM connector terminals A31, D2, D6and D12 individually.

Is there continuity?

YES - Repair short in the wire between the ECM/PCM (A31, D2, D6, or D12) and each sensor, then go to step 43.

NO - Go to step 49.

43. Turn the ignition switch OFF.
44. Reconnect all connectors.
45. Turn the ignition switch ON (II).
46. Reset the ECM/PCM with the HDS.
47. Do the ECM/PCM idle learn procedure. Programming and Relearning
48. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0641 Indicated?

YES - Check for poor connections or loose terminals at the ECM/PCM and these connectors:
- MAP sensor
- APP sensor
- IMT(IMRC) actuator
- EGR valve
- FTP sensor
- Input shaft (mainshaft) speed sensor
- Output shaft (countershaft) speed sensor

After checking above, go to step 1.

NO - Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTCs troubleshooting.

49. Reconnect all connectors.
50. Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM.
51. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0641 indicated?

YES - Check for poor connections or loose terminals at the ECM/PCM and these connectors:
- MAP sensor
- APP sensor
- IMT(IMRC) actuator
- EGR valve
- FTP sensor
- Input shaft (mainshaft) speed sensor
- Output shaft (countershaft) speed sensor

If the ECM/PCM was updated, substitute a known-good ECM/PCM, then recheck. If the ECM/PCM was substituted, go to step 1.

NO - If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was substituted, replace the original ECM/PCM. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTCs troubleshooting.