B2991

DTC Troubleshooting: B2991 (AUDIO communication error)

DTC B2991 or Audio communication error is indicated:

Climate Control Unit Lost Communication with Audio System

1. Clear the DTC with the HDS.

2. Turn the ignition switch to LOCK (0), and then back to ON (II).

3. Do the self-diagnostic with the HDS or the climate control unit.

4. Check for DTCs.

Is DTC B2991 or Audio communication error indicated?

YES -

Go to step 5.

NO -

Intermittent failure. Check for loose wires or poor connections on the audio unit circuit.�

5. Turn the ignition switch to LOCK (0).

6. Disconnect audio unit connector B (32P).

7. Disconnect the climate control unit 40P connector.

8. Check for continuity between the following terminals of the climate control unit 40P connector and audio unit connector B (32P).









Is there continuity?

YES -

Go to step 9.

NO -

Repair an open in the wire(s) between the climate control unit and the audio unit.�

9. Check for continuity between body ground and climate control unit 40P connector terminals No. 29 and No. 30 individually.





Is there continuity?

YES -

Repair a short to body ground in the wire(s) between the climate control unit and the audio unit.�

NO -

Go to step 10.

10. Check for continuity between climate control unit 40P connector terminals No. 29 and No. 30.





Is there continuity?

YES -

Repair a short in the wires between the climate control unit and the audio unit.�

NO -

Check for loose wires or poor connections at the climate control unit 40P connector and at audio unit connector B (32P). If the connections are good, substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit Climate Control Unit Removal/Installation. If the symptom/indication continues, substitute a known-good audio unit, and recheck. If the symptom/indication goes away, replace the original audio unit.�