DTC U128D: Lost Communication with Gauge Control Module (Climate Control Unit)

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).

Clear the DTCs with the HDS.
Turn the ignition switch to LOCK (0), and then back to ON (II).
Do the Self-Diagnostic Function with the HDS (see HOW TO USE THE SELF-DIAGNOSTIC FUNCTION WITH THE HDS ).
Check for DTCs.
Is DTC U128D indicated?

YES -Go to step 5.

NO -The system is OK at this time. Check for loose wires or poor connections on the gauge control module and climate control unit circuit.
Select B-CAN Control Units Information in the BODY ELECTRICAL menu.
Select Check Connected Control Units in the B-CAN Control Units Information menu.
Is the gauge control module detected?

YES -Substitute a known-good climate control unit, and recheck. If the symptom/indication goes away, replace the original climate control unit (see CLIMATE CONTROL UNIT REMOVAL/INSTALLATION ).

NO -Go to step 7.
Turn the ignition switch to LOCK (0).
Disconnect the gauge control module 32P connector.
Disconnect climate control unit connector A (28P).

Check for continuity between the following terminals of the gauge control module 32P connector and climate control unit connector A (28P).

CONTINUITY REFERENCE

32P:	28P:
No. 29	No. 26
No. 30	No. 28

Fig 1: Checking Continuity Between Terminals Of Gauge Control Module Connector And Climate Control Unit Connector

Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Go to the gauge control module input test (see GAUGE CONTROL MODULE INPUT TEST ).

NO -Repair an open in the wire between the climate control unit and the gauge control module.