DTC B2981: Climate Control Unit Lost Communication with Navigation 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 the DTCs.
Is DTC B2981 indicated?

YES - Go to step 5.

NO - Intermittent failure, check for loose wires or poor connections on the navigation unit and climate control unit circuit.
Turn the ignition switch to LOCK (0).
Disconnect navigation unit connector A (20P).
Disconnect climate control unit connector A (40P).

Check for continuity between the following terminals of climate control unit connector A (40P) and navigation unit connector A (20P).

40P	20P
No. 2	No. 4
No. 21	No. 15
No. 22	No. 14

Fig 1: Identifying Continuity Between Climate Control Unit A (40P) And Navigation Unit Connector A (20P) Terminals

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES - Go to step 9.

NO - Repair open in the wire(s) between the climate control unit and the navigation unit.

Check for continuity between body ground and navigation unit connector A (20P) No. 4,14, and 15 terminals individually.

Fig 2: Identifying Continuity Between Body Ground And Navigation Unit Connector A (20P) No. 4,14, And 15 Terminals
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

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

NO - Go to step 10.

Check for continuity between navigation unit connector A (20P) terminals as follows.

TERMINALS REFERENCE CHART

From terminal	To terminals
4	14, 15
14	15

Is there continuity between any of the terminals?

YES - Repair the short in the wires.

NO - Substitute a known-good navigation unit, and recheck. If the symptom goes away, replace the original navigation unit. If the symptom remains, substitute a known-good climate control unit and recheck. If the symptom goes away, replace the original climate control unit.