DTC B2991: Climate Control Unit Lost Communication with Audio Unit
WARNING: This page is about a different car, the 2009 Acura MDX, 2008 Acura MDX, and 2007 Acura MDX. However, it is still accessible from the selected car via links, so may be relevant.
- Clear the DTC with the HDS.
- Turn the ignition switch to LOCK (0), and then ON (II).
- Do the self-diagnostic with the HDS (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITH THE HDS ).
- Check for DTCs.
Is DTC B2991 indicated?
YES - Go to step 5.
NO - Intermittent failure, check for loose wires or poor connections on the rear climate control panel and climate control unit circuit.
- Turn the ignition switch to LOCK (0).
- Disconnect climate control unit connector B (14P).
- Disconnect audio unit connector C (24P).
- Check for continuity between climate control unit connector B (14P) No. 8 terminal and audio unit connector C (24P) No. 24 terminal.Fig 1: Identifying Continuity Between Climate Control Unit Connector B (14P) No. 8 And No. 24 Terminal
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES - Go to step 9.
NO - Repair open in the wire between the climate control unit and the audio unit.
- Check for continuity between climate control unit connector B (14P) No. 8 terminal and body ground.Fig 2: Identifying Continuity Between Climate Control Unit Connector B (14P) No. 8 Terminal And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there continuity?
YES - Repair short to body ground in the wire between the climate control unit and the audio unit.
NO - 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 remains, substitute a known-good audio unit. If the symptom/indication goes away, replace the original audio unit.