DTC Troubleshooting: P1549 (34)

DTC P1549:  Charging System High Voltage

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

1.Turn the ignition switch 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 (min-1) (in Park or neutral) for 1 minute.

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

Is DTC P1549 indicated?


YES - Do the alternator overhaul, then go to 7.


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


7.Turn the ignition switch ON (II).

8.Reset the ECM/PCM with the HDS.

9.Do the ECM/PCM 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 (min-1) (in Park or neutral) for 1 minute.

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

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P1549 is indicated, check for poor connections or loose terminals at the alternator and the under-hood fuse/relay box, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


NO - Troubleshooting is complete.n