DTC Troubleshooting

DTC Troubleshooting: P1549

DTC P1549: Charging System High Voltage

NOTE:

- Before you troubleshoot, record all freeze data and any on-board snapshot, and review the general troubleshooting information. Initial Inspection and Diagnostic Overview

- If a high voltage battery (24 V, etc.) connected to the vehicle, this DTC can be stored.

1. Turn the ignition switch to ON (II).

2. Clear the DTC with the HDS.

3. Start the engine.

4. Check under these conditions:
- A/C off

- Headlights off

- Rear window defogger off

5. Hold the engine speed at 2,000 rpm (in neutral) for 1 minute.

6. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1549 indicated?
YES - Replace the alternator, Removal and Replacement then go to step 7.

NO - Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the alternator and the under-hood fuse/relay box.


7. Turn the ignition switch to ON (II).

8. Reset the ECM with the HDS.

9. Do the ECM idle learn procedure. ECM Idle Learn Procedure

10. Start the engine.

11. Check under these conditions:
- A/C off

- Headlights off

- Rear window defogger off

12. Hold the engine speed at 2,000 rpm (in neutral) for 1 minute.

13. Check for Temporary DTCs or DTCs with the HDS.

Is DTC P1549 indicated?
YES - Check for poor connections or loose terminals at the alternator and the under-hood fuse/relay box, 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.