DTC U128D: MICU Lost Communication With Gauge Control Module

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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).
Wait for at least 6 seconds.
Check for DTCs with the HDS.
Is DTC U128D indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time. Check for loose or poor connections between the MICU and the gauge control module.
Measure the voltage between body ground and gauge control module 32P connector terminals No. 1 and No. 17 individually.

Fig 1: Measuring Voltage Between Body Ground And Gauge Control Module 32P Connector Terminals No. 1 And No. 17
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 8.

NO -Go to step 6.
Turn the ignition switch to LOCK (0).
Check the No. B16 (10 A) fuse in the under-hood fuse/relay box and the No. C11 (7.5 A) fuse in the driver's under-dash fuse/relay box.
Are the fuses OK?

YES -Repair an open or high resistance in the No. B16 (10 A) and/or No. C11 (7.5 A) fuse circuit.

NO -Replace the fuse(s). If the fuse blows again, repair a short to ground in the No. B16 (10 A) and/or No. C11 (7.5 A) fuse circuit.
Measure the voltage between body ground and gauge control module 32P connector terminal No. 4.

Fig 2: Measuring Voltage Between Body Ground And Gauge Control Module 32P Connector Terminal No. 4
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there less than 0.2 V?

YES -Go to step 9.

NO -Repair an open or high resistance in the ground wire or poor ground (G401).
Turn the ignition switch to LOCK (0).
Disconnect driver's under-dash fuse/relay box connector H(13P).
Disconnect the gauge control module 32P connector.
Check for continuity between driver's under-dash fuse/relay box connector H (13P) terminals No. 5 and No. 10 and gauge control module 32P connector terminals No. 29 and No. 30 respectively.

Fig 3: Checking Continuity Between Driver's Under-Dash Fuse/Relay Box Connector H (13P) Terminals No. 5 And No. 10
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Replace the gauge control module (see GAUGE CONTROL MODULE REPLACEMENT ).

NO -An open or poor connection in the B-CAN wire between the MICU and the gauge control module.