B2991

DTC B2991 or Audio communication error is indicated.:
Climate Control Unit Lost Communication with Audio Unit

1. Clear the DTC with the HDS.
2. Operate the climate control system in several modes.
3. Check for DTCs using the HDS or self-diagnostic.

Is DTC B2991 or Audio communication error indicated?

YES - Go to step 4.

NO - Intermittent failure, check for loose wires or poor connections on the audio unit circuit.

4. Turn the ignition switch OFF.
5. Disconnect audio unit connector B (32P).
6. Disconnect the climate control unit 40P connector.




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

Is there continuity?

YES - Go to step 8.
NO - Repair any open in the wire(s) between the climate control unit and the audio unit.




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

Is there continuity?

YES - Repair any short to body ground in the wire(s) between the climate control unit and the audio unit.

NO - Go to step 9.




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

Is there continuity?

YES - Repair 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. If the symptom/indication continues, substitute a known-good audio unit, and recheck. If the symptom/indication goes away, replace the original audio unit.