DTC Troubleshooting
DTC Troubleshooting: P0641, P0641
DTC P0641:
Sensor Reference Voltage A Malfunction
NOTE: Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information Initial Inspection and Diagnostic Overview.
1. Turn the ignition switch to ON (II).
2. Clear the DTC with the HDS.
3. Check for Pending or Confirmed 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 the connectors of these parts:�
- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor
4. Turn the ignition switch to LOCK (0).
5. Disconnect the connectors of these parts:
- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor
6. Turn the ignition switch ON (II).
7. Clear the DTC with the HDS.
8. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0641 indicated?
YES -
Go to step 10.
NO -
Go to step 9.
9. Check for Pending or Confirmed DTCs with the HDS while connecting each connectors of these parts:
- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor
Is DTC P0641 indicated?
YES -
Replace the part that caused the DTC when it was reconnected, then go to step 14.
NO -
Check for poor connections or loose terminals at the ECM/PCM and the connectors of these parts:
- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor
If the connections and the terminals are OK, go to step 1 and recheck.
10. Turn the ignition switch to LOCK (0).
11. Jump the SCS line with the HDS.
12. Disconnect ECM/PCM connectors A (49P), B (49P), and C (49P).
13. Check for continuity between body ground and ECM/PCM connector terminals A24, B18, and C12 individually.
Is there continuity?
YES -
Repair short in the wire between the ECM/PCM (A24, B18, or C12) and each sensor, then go to step 14.
NO -
Go to step 20.
14. Turn the ignition switch to LOCK (0).
15. Reconnect all connectors.
16. Turn the ignition switch to ON (II).
17. Reset the ECM/PCM with the HDS.
18. Do the ECM/PCM idle learn procedure ECM/PCM Idle Learn Procedure.
19. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0641 indicated?
YES -
Check for poor connections or loose terminals at the ECM/PCM and the connectors of these parts:
- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor
If the connections and the terminals are OK, go to step 1 and recheck.
NO -
Troubleshooting is complete. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.�
20. Reconnect all connectors.
21. Update the ECM/PCM if it does not have the latest software ECM/PCM Update, or substitute a known-good ECM/PCM Initial Inspection and Diagnostic Overview.
22. Check for Pending or Confirmed DTCs with the HDS.
Is DTC P0641 indicated?
YES -
If the ECM/PCM was updated, substitute a known-good ECM/PCM Initial Inspection and Diagnostic Overview, then recheck. If the ECM/PCM was substituted, check for poor connections or loose terminals at the ECM/PCM and the connectors of these parts:
- Throttle body
- EGR valve
- Input shaft (mainshaft) speed sensor
- APP sensor
If the connections and the terminals are OK, 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 Initial Inspection and Diagnostic Overview. If any other Pending or Confirmed DTCs are indicated, go to the indicated DTC's troubleshooting.�