DTC B1171: Gauge Control Module Lost Communication with Adaptive Cruise Control Unit (ACC Message)

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A 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 B1171 indicated?

YES -Go to step 5.

NO -Intermittent failure, the system is OK at this time. Check for loose or poor connection between the gauge control module and the ACC unit.
Check for ACC System DTCs with the HDS HOW TO TROUBLESHOOT DTCS ).
Are there any DTCs Indicated?

YES -Go to and troubleshoot the indicated DTCs, then recheck.

NO -Go to step 6.
Turn the ignition switch to LOCK (0).
Disconnect gauge control module connector A (12P).
Disconnect the ACC unit 20P connector.
Check for continuity between ACC unit 20P connector terminals No. 10 and No. 20 and gauge control module connector A (12P) connector terminals No. 12 and No. 6 respectively.

Fig 1: Checking Continuity Between 20P Connector And Connector A (12P) Connector
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

YES -Substitute a known-good ACC unit ADAPTIVE CRUISE CONTROL (ACC) UNIT REMOVAL/INSTALLATION ), and recheck. If the indication goes away, replace the original ACC unit ADAPTIVE CRUISE CONTROL (ACC) UNIT REMOVAL/INSTALLATION ). If the DTC is still present, replace the gauge control module

NO -Repair an open in the wire.