DTC U0100: Gauge Control Module Lost Communication with PCM

WARNING: This page is about a different car, the 2011 Acura TL, 2010 Acura TL, and 2009 Acura TL. However, it is still accessible from the selected car via links, so may be relevant.

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), or press the engine start/stop button to select the OFF mode and then the ON mode
Start and run the engine for at least 5 seconds, then turn the engine off
Check for DTCs with the HDS
Is DTC U0100 indicated?

YES -Go to step 5

NO -Intermittent failure, the F-CAN communication line is OK at this time Check for DTCs in the PCM with the HDS If F-CAN DTCs are present, check for loose or poor connections at the gauge control module and the PCM If the connections are good, check the battery condition and the charging system, then clear all DTCs
Check for DTCs in the PCM with the HDS
Are any DTCs indicated?

YES -Go to the PCM indicated DTC's troubleshooting

NO -Go to step 6
Turn the ignition switch to LOCK (0), or press the engine start/stop button to select the OFF mode.
Short the SCS line with the HDS.
Disconnect the ECM/PCM connector A (49P).
Check for continuity between gauge control module 32P connector terminals No. 9 and No. 10 and ECM/PCM connector A (49P) terminals No. 49 and No. 48 respectively.

Fig 1: Checking For Continuity Between Gauge Control Module 32P Connector And ECM/PCM Connector A (49P)
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Substitute a known-good ECM/PCM (see ECM/PCM REPLACEMENT ), and recheck. If the indication goes away, replace the original ECM/PCM. If the DTC is still present, replace the gauge control module (see GAUGE CONTROL MODULE REPLACEMENT ).

NO -Repair an open or poor connection in the wire between the ECM/PCM and the gauge control module.