DTC U128D: Lost Communication with Gauge Control Module (Climate Control Unit); DTC Indicator 81: Climate Control Unit Lost Communication with Gauge Control Module (ECT message); DTC Indicator 83: Climate Control Unit Lost Communication with Gauge Control Module (VSP message)

DTC (AC)

1. Problem verification

   -1. Clear the DTCs with the HDS.

   - 2. Turn the vehicle to the OFF (LOCK) mode and then the ON mode.

   - 3. Do the Self-Diagnostic Function with the HDS or the climate control unit.

   - 4. Check for DTCs.

   DTC Description	DTC
   U128D Lost communication with gauge control module (climate control unit)

   Is DTC U128D or 81 and/or 83 indicated?

   YES 

   Go to step 2.

   NO 

   Intermittent failure, the system is OK at this time. Check for loose or poor connections.

2. Determine possible failure area (gauge control module power and ground, B-CAN lines)

   -1. Select B-CAN Control Units Information from the Body Electrical System Select menu, and then select Check Connected Control Units.

   - 2. Check the DETECT/NOT AVAILABLE information of the GAUGE CONTROL MODULE.

   Is DETECT indicated?

   YES 

   Go to step 3.

   NO 

   Go to step 4.

3. Open wire check (B-CAN_H line)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Disconnect the following connectors.

   Gauge control module connector A (32P)

   Climate control unit connector A (32P)

   - 3. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Gauge control module connector A (32P): disconnected
   	Climate control unit connector A (32P): disconnected
   Test circuit	B-CAN_H
   Test point 1	Gauge control module connector A (32P) No. 30 (PNK)
   Test point 2	Climate control unit connector A (32P) No. 32 (PNK)

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   Repair an open or poor connection in the B-CAN_L wire between the climate control unit and the gauge control module.

   NO 

   Repair an open or poor connection in the B-CAN_H wire between the climate control unit and the gauge control module.

4. Fuse check

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Check the following fuses.

   Fuse	No. A21 (10 A)
   Location	Under-hood fuse/relay box

   Fuse	No. B5 (10 A)
   Location	Under-dash fuse/relay box

   Are the fuses OK?

   YES 

   Go to step 5.

   NO 

   Replace the fuse, and recheck. If the fuse blow again, repair a short in the No. A21 (10 A) or No. B5 (10 A) fuse circuit.

5. Open wire check (+B BACK UP line)

   -1. Disconnect the following connector.

   Gauge control module connector A (32P)

   - 2. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Gauge control module connector A (32P): disconnected
   Test circuit	+B BACK UP
   Test point 1	Gauge control module connector A (32P) No. 1 (WHT)
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Is there battery voltage?

   YES 

   The +B BACK UP wire is OK. Go to step 6.

   NO 

   Repair an open in the +B BACK UP wire.

6. Open wire check (IG1 METER line)

   -1. Turn the vehicle to the ON mode.

   - 2. Measure the voltage between test points 1 and 2.

   Test condition	Vehicle ON mode
   	Gauge control module connector A (32P): disconnected
   Test circuit	IG1 METER
   Test point 1	Gauge control module connector A (32P) No. 17 (BRN)
   Test point 2	Body ground

   Courtesy of HONDA, U.S.A., INC.

   Is there battery voltage?

   YES 

   The IG1 METER wire is OK. Go to step 7.

   NO 

   Repair an open in the IG1 METER wire.

7. Open wire check (GND lines)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Check for continuity between test points 1 and 2 individually.

   Test condition	Vehicle OFF (LOCK) mode
   	Gauge control module connector A (32P): disconnected
   Test circuit	GND
   Test point 1	Gauge control module connector A (32P) No. 4 (BRN)
   Test point 2	Body ground

   Test circuit	GND
   Test point 1	Gauge control module connector A (32P) No. 32 (BRN)

   Test point 2

   Body ground

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The GND wires are OK. Go to step 8.

   NO 

   Check for an open in the wire(s) between the gauge control module and body ground. If the wire(s) is OK, check for poor ground at G502.

8. Open wire check (B-CAN_H line)

   -1. Disconnect the following connector.

   Climate control unit connector A (32P)

   - 2. Check for continuity between test points 1 and 2.

   Test condition	Vehicle OFF (LOCK) mode
   	Gauge control module connector A (32P): disconnected
   	Climate control unit connector A (32P): disconnected
   Test circuit	B-CAN_H
   Test point 1	Gauge control module connector A (32P) No. 30 (PNK)
   Test point 2	Climate control unit connector A (32P) No. 32 (PNK)

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   Repair an open or poor connection in the B-CAN_L wire between the climate control unit and the gauge control module.

   NO 

   Repair an open or poor connection in the B-CAN_H wire between the climate control unit and the gauge control module.