DTC U128B: Gauge Control Module Lost Communication With Power 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.
Press the engine start/stop button to select the OFF, ACC, and ON mode.
Wait for at least 6 seconds.
Check for DTCs with the HDS.
Is DTC U128B indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time. Check for loose or poor connections between the keyless access control unit and the gauge control module
From the BODY ELECTRICAL SYSTEM SELECT menu, select B-CAN CONTROL UNITS INFORMATION, and then select CHECK CONNECTED CONTROL UNITS.
Is the keyless access control unit detected?

YES -Go to step 10.

NO -Go to step 6.
Measure the voltage between body ground and keyless access control unit connector A (32P) terminal No. 1.

Fig 1: Measuring the voltage between body ground and keyless access control unit connector A (32P) terminal No. 1.
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 9.

NO -Go to step 7.
Press the engine start/stop button to select the OFF mode.
Check the No. C18 (10 A) fuse in the driver's under-dash fuse/relay box.
Is the fuse OK?

YES -Repair an open or high resistance in the No. B16 (10 A) and/or No. C18 (10 A) fuse circuit.

NO -Replace the fuse. If the fuse blows again, repair a short to ground on the No. C18(10 A) fuse circuit
Measure the voltage between body ground and keyless access control unit connector A (32P) and B (36P) terminals as shown.

Fig 2: Measuring the voltage between body ground and keyless access control unit connector A (32P) and B (36P) terminals as shown.
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there less than 0.2 V?

YES -Go to step 10.

NO -Repair an open or high resistance in the ground wire or poor ground (G403).
Press the engine start/stop button to select the OFF mode.
Disconnect keyless access control unit connector C (20P).
Disconnect gauge control module 32P connector.
Check for continuity between keyless access control unit connector C (20P) terminals No. 1 and No. 11 and gauge control module 32P connector terminals No. 29 and No. 30 respectively.

Fig 3: Checking for continuity between keyless access control unit connector C (20P) terminals No. 1 and No. 11 and gauge control module 32P connector terminals No. 29 and No. 30 respectively.
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Replace the keyless access control unit.

NO -Repair an open or poor connection in the B-CAN wire(s) between the keyless access control unit and the gauge control module