DTC Troubleshooting

DTC P16BC: Alternator FR Terminal Circuit/IGP Circuit Low Voltage ('06-08 models)

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

1. Check for poor connections or loose terminals at the alternator 4P connector.

Are the connections and terminals OK?

YES - Go to step 2.

NO - Repair the connections or terminals, then go to step 20.

2. Check the alternator mounting surface for corrosion.

Is the mounting surface corroded?

YES - Remove the alternator. Clean all mounting surface and reinstall the alternator, then go to step 20.

NO - Go to step 3.

3. Turn the ignition switch ON (II).
4. Clear the DTC with the HDS.
5. Start the engine.
6. Check under these conditions:

- A/C on
- Temperature control at maximum cool
- Blower fan at maximum speed
- Rear window defogger on
- Headlights on high beam

7. Hold the engine speed at 2,000 rpm (in Park or neutral) for 1 minute.
8. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P16BC indicated?

YES - Go to step 9.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the alternator.

9. Turn the ignition switch OFF.
10. Disconnect the alternator 4P connector.
11. Turn the ignition switch ON (II).
12. Measure voltage between alternator 4P connector terminal No. 1 and body ground.






Is there battery voltage?

YES - Go to step 13.

NO - Repair open in the wire between the alternator (IG1 line) and the No. 18 ACG (15 A) fuse in the under-dash fuse/relay box, then go to step 19.

13. Measure voltage between alternator 4P connector terminal No. 4 and body ground.






Is there about 5 V?

YES - Replace the alternator, then go to step 19.

NO - Go to step 14.

14. Turn the ignition switch OFF.
15. Jump the SCS line with the HDS.
16. Disconnect ECM/PCM connector B (24P).
17. Connect alternator 4P connector terminal No. 4 to body ground with a jumper wire.






18. Check for continuity between ECM/PCM connector terminal B13 and body ground.






Is there continuity?

YES - Go to step 28.

NO - Repair open in the wire between the ECM/PCM (B13) and the alternator, then go to step 20.

19. Turn the ignition switch OFF.
20. Reconnect all connectors.
21. Turn the ignition switch ON (II).
22. Reset the ECM/PCM with the HDS.
23. Do the ECM/PCM idle learn procedure.
24. Start the engine.
25. Check under these conditions:

- A/C on
- Temperature control at maximum cool
- Blower fan at maximum speed
- Rear window defogger on
- Headlights on high beam

26. Hold the engine speed at 2,000 rpm (in Park or neutral) for 1 minute.
27. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P16BC indicated?

YES - Check for poor connections or loose terminals at the alternator and the ECM/PCM, then go to step 1.

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

28. Reconnect all connectors.
29. Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM.
30. Start the engine.
31. Check under these conditions:

- A/C on
- Temperature control at maximum cool
- Blower fan at maximum speed
- Rear window defogger on
- Headlights on high beam

32. Hold the engine speed at 2,000 rpm (in Park or neutral) for 1 minute.
33. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P16BC indicated?

YES - Check for poor connections or loose terminals at the alternator and the ECM/PCM. If the ECM/PCM was updated, substitute a known-good ECM/PCM, then go to step 30. 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 DTC's troubleshooting.