P0651

DTC P0651: Sensor Reference Voltage B Circuit Malfunction

NOTE: Information marked with an asterisk (*) applies to DTC P0651.

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 and/or P0651 indicated?

YES - If P0641 is indicated, go to step 4. If P0651 is indicated, go to step 19.

NO - Intermittent failure, system is OK at this time. Check for poor connections or loose terminals between the PCM and the following connectors:
- MAP sensor
- APP sensor (sensor 1)
- Output shaft (countershaft) speed sensor
- IMRC actuator*
- Input shaft (mainshaft) speed sensor*
- EGR valve position sensor*
- APP sensor (sensor 2)*
- FTP 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 49.

9. Turn the ignition switch OFF.
10. Disconnect the APP sensor (sensor 1) 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 49.

14. Turn the ignition switch OFF.
15. Disconnect the output shaft (countershaft) speed sensor 3P 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 43.

NO - Replace the output shaft (countershaft) speed sensor, then go to step 49.

19. Turn the ignition switch OFF.
20. Disconnect the IMRC actuator* 16P connector.
21. Turn the ignition switch ON (II).
22. Clear the DTC with the HDS.
23. Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS.

Is DTC P0651 indicated?

YES - Go to step 24.

NO - Replace the IMRC actuator*, then go to step 49.

24. Turn the ignition switch OFF.
25. Disconnect the input shaft (mainshaft) speed 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 P0651 indicated?

YES - Go to step 29.

NO - Replace the input shaft (mainshaft) speed sensor*, then go to step 49.

29. Turn the ignition switch OFF
30. Disconnect the EGR valve position sensor* 5P 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 P0651 indicated?

YES - Go to step 34.

NO - Replace the EGR valve position sensor*, then go to step 49.

34. Turn the ignition switch OFF.
35. Disconnect the APP sensor (sensor 2)* 6P 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 P0651 indicated?

YES - Go to step 39.

NO - Replace the APP sensor (sensor 2)*, then go to step 49.

39. Turn the ignition switch OFF.
40. Disconnect the FTP sensor* 3P connector.
41. Turn the ignition switch ON (II).
42. Clear the DTC with the HDS.
43. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P0651 indicated?

YES - Go to step 44.

NO - Replace the FTP sensor*, then go to step 49.

44. Jump the SCS line with the HDS.
45. Turn the ignition switch OFF.
46. Disconnect PCM connector A (73P).
47. Disconnect PCM connector B (56P).







48. Check for continuity between the PCM connector terminals (A7/A27* B43/B29*, B46*) and body ground.

Is there continuity?

YES - Repair short in the wire between the PCM (A7, B43/A27*, B29*, B46*) and the body ground.

NO - Go to step 53.

49. Turn the ignition switch ON (II).
50. Reset the PCM with the HDS.
51. Do the PCM idle learn procedure.
52. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES - If DTC P0641 and/or P0651 is indicated, check for poor connections or loose terminals between the PCM and the following connector:
- MAP sensor
- APP sensor (sensor 1)
- Output shaft (countershaft) speed sensor
- IMRC actuator*
- Input shaft (mainshaft) speed sensor*
- EGR valve position sensor*
- APP sensor (sensor 2)*
- FTP sensor*

After checking above, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.

NO - Troubleshooting is complete.

53. Update the PCM if it does not have the latest software, or substitute a known-good PCM.
54. Do the PCM idle learn procedure.
55. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES - If DTC P0641 and/or P0651 indicated, check for poor connections or loose terminals between the PCM and the following connector:
- MAP sensor
- APP sensor (sensor 1)
- Output shaft (countershaft) speed sensor
- IMRC actuator*
- Input shaft (mainshaft) speed sensor*
- EGR valve position sensor*
- APP sensor (sensor 2)*
- FTP sensor*

After checking above, then go to step 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.

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