B421 BCM Output Driver #2 Failure

Code B421:

BCM Output Driver #2 Circuit:

DESCRIPTION:

The BCM has the ability of both commanding an output and checking that the commanded state has been achieved. Code B421 will set if the state of the RAP relay output, headlamps on chime output, or ABS diagnostic enable output are high when the BCM has commanded low or are low when the BCM has commanded high.

TEST DESCRIPTION: The numbers below refer to circled numbers on the diagnostic chart.

1. It would be normal for code B421 to set if there was an ABS fault (code B480 or B481), therefore, diagnose the ABS codes if set.

2. This checks for proper chime control.

3. This checks for proper RAP control.

NOTE ON INTERMITTENTS:

If code this code is setting intermittently along with code B480 or B481 then the ABS system should be diagnosed. If no other codes are set, symptoms of no RAP or chime operation may direct area to diagnose.