DTC B1906: Immobilizer-Keyless Control 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.
Select the BODY ELECTRICAL system select menu, then enter UNIT INFORMATION menu.
Check the condition of the gauge control module from the CONNECTED UNIT.
Is NOT AVAILABLE indicated?

YES -Go to step 7.

NO -Replace the gauge control module (see GAUGE CONTROL MODULE REPLACEMENT ).
Turn the ignition switch to LOCK (0).
Disconnect the gauge control module 36P connector.
Turn the ignition switch to ON (II).
Measure the voltage between gauge control module 36P connector terminals No. 18 and No. 36 and body ground individually.

Fig 1: Measuring Voltage Between Gauge Control Module 36P Connector Terminals No. 18 And No. 36 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there battery voltage?

YES -Go to step 11.

NO -Check the No. 23 (10 A) fuse in the under-hood fuse/relay box and the No. 10 (7.5 A) fuse 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.
Turn the ignition switch to LOCK (0).
Measure the voltage between gauge control module 36P connector terminals No. 15 and No. 19 and body ground individually.

Fig 2: Measuring Voltage Between Gauge Control Module 36P Connector Terminals No. 15 And No. 19 And Body Ground
Courtesy of AMERICAN HONDA MOTOR CO., INC.

Is there less than 0.2V?

YES -Go to step 13.

NO - Repair an open or high resistance in the wire or poor ground (G501).
Disconnect under-dash fuse/relay box connector Q (16P).
Check for continuity between under-dash fuse/relay box connector Q (16P) terminal No. 6 and the gauge control module 36P connector terminal No. 20.

Fig 3: Checking Continuity Between Under-Dash Fuse/Relay Box Connector Q (16P) Terminal No. 6 And Gauge Control Module 36P Connector Terminal No. 20
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 in the wire between the under-dash fuse/relay box and the gauge control module.