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

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 8.

NO - Go to 6.
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 7.

NO -Check the No. B1 (15 A) and the No. B22 (7.5 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 body ground and gauge control module 32P connector terminals No. 4 and No. 32 individually.

Fig 2: Measuring Voltage Between Body Ground And Gauge Control Module 32P Connector Terminals No. 4 And No. 32
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 under-dash fuse/relay box connector Y (16P).
Check for continuity between immobilizer-keyless control unit up connector terminal No. 4 and gauge control module 32P connector terminal No. 31.

Fig 3: Checking Continuity Between Immobilizer-Keyless Control Unit up Connector Terminal No. 4 And Gauge Control Module 32P Connector Terminal No. 31
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there continuity?

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

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