DTC B1906: Immobilizer-Keyless Control Unit Lost Communication With Gauge Control Module (A/T Message)

WARNING: This page is about a different car, the 2013 Honda Fit, 2012 Honda Fit, 2011 Honda Fit, 2010 Honda Fit, and 2009 Honda Fit. 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).
Wait for at least 6 seconds.
Check for DTCs with the HDS.
Is DTC B1906 indicated?

YES - Go to step 5.

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

YES - Go to step 8

NO - Go to step 6
Measure the voltage between gauge control module 32P connector terminals No. 16 and No. 32 and body ground individually.

Fig 1: Measuring Voltage Between Gauge Control Module 32P Connector Terminals No. 16 & 32 With Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES - Go to step 8.

NO - Check the No. 1 (10 A) and the No. 20 (15 A) fuses in the under-dash fuse/relay box. If the fuse is blown, replace the fuse and recheck the DTCs. If the fuses are OK, repair an open in the wire between the under-dash fuse/relay box and the gauge control module.
Measure the voltage between gauge control module 32P connector terminals No. 13 and No. 17 and body ground indiviually.

Fig 2: Measuring Voltage Between Gauge Control Module 32P Connector Terminals And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there less than 0.2 V?

YES - Go to step 8.

NO - Repair an open or high resistance in the wire or poor ground (G501).
Turn the ignition switch to LOCK (0).
Disconnect immobilizer-keyless control unit 7P connector.
Check for continuity between immobilizer-keyless control unit 7P connector terminal No. 4 and the gauge control module 32P connector terminal No. 18.
Is there continuity?

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

NO - Repair an open or high resistance in the wire.

Fig 3: Checking Continuity Between 7P Connector Terminal No. 4 & Gauge Control Module 32P Connector Terminal No. 18
Courtesy of AMERICAN HONDA MOTOR CO., INC.