DTC U128D: Keyless Access Control Unit Lost Communication With Gauge Control Module (Keyless Access Control Unit)

DTC (Keyless Access Control Unit)

1. Problem verification

   - 1. Clear the DTCs with the HDS.

   - 2. Press the engine start/stop button to select the OFF mode and then the ON mode.

   - 3. Wait for at least 6 seconds.

   - 4. Check for DTCs with the HDS.

   DTC Description	DTC
   U128D Keyless Access Control Unit Lost Communication with Gauge Control Module

   Is DTC U128D indicated?

   YES 

   Go to step 2 below.

   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 line)

   - 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  8.

   NO 

   Go to step 3 below.

3. Fuse check

   - 1. Check the following fuses.

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

   Fuse	No. B5 (7.5 A)
   Location	Under-dash fuse/relay box

   Is each fuse OK?

   YES 

   Go to step 4 below.

   NO 

   Replace the fuse. If the fuse blows again, repair a short to ground in the No. A21 (10 A) and/or the No. B5 (7.5 A) fuse circuit (s).

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

   - 1. Press the engine start/stop button to select the OFF mode.

   - 2. Disconnect the following connector.

   Gauge control module connector A (32P)

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

   Test condition	OFF 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 5 below.

   NO 

   Repair an open or high resistance in the wire.

5. Open wire check (IG1 METER line)

   - 1. Press the engine start/stop button to select the ON mode.

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

   Test condition	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 6 below.

   NO 

   Repair an open or high resistance in the wire.

6. Open wire check (GND lines)

   - 1. Press the engine start/stop button to select the OFF mode.

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

   Test condition	OFF 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 7 below.

   NO 

   Repair an open or high resistance in the ground wire or poor ground (G502).

7. Open wire check (B CAN lines)

   - 1. Disconnect the following connector.

   Keyless access control unit connector B (28P)

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

   Test condition	OFF mode
   	Gauge control module connector A (32P): disconnected
   	Keyless access control unit connector B (28P): disconnected
   Test circuit	B CAN-H
   Test point 1	Keyless access control unit connector B (28P) No. 6 (PNK)
   Test point 2	Gauge control module connector A (32P) No. 30 (PNK)

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

   Is there continuity?

   YES 

   An open or poor connection in the B CAN-L wire between the keyless access control unit and the gauge control module.

   NO 

   An open or poor connection in the B CAN-H wire between the keyless access control unit and the gauge control module.

8. Open wire check (B CAN lines)

   - 1. Press the engine start/stop button to select the OFF mode.

   - 2. Disconnect the following connectors.

   Gauge control module connector A (32P)

   Keyless access control unit connector B (28P)

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

   Test condition	OFF mode
   	Gauge control module connector A (32P): disconnected
   	Keyless access control unit connector B (28P): disconnected
   Test circuit	B CAN-H
   Test point 1	Keyless access control unit connector B (28P) No. 6 (PNK)
   Test point 2	Gauge control module connector A (32P) No. 30 (PNK)

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

   Is there continuity?

   YES 

   An open or poor connection in the B CAN-L wire between the keyless access control unit and the gauge control module.

   NO 

   An open or poor connection in the B CAN-H wire between the keyless access control unit and the gauge control module.