Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC B1906: Immobilizer-Keyless Control Unit Lost Communication With Gauge Control Module (A/T Message)
- 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.
- Turn the ignition switch to LOCK (0).
- Connect the HDS to the data link connector, then turn the ignition switch to ON (II).
- Select the BODY ELECTRICAL menu, then enter the UNIT INFORMATION.
- Check the condition of the gauge control module from the CONNECTED UNITS list.
Is NOT AVAILABLE indicated?
YES -Go to step 9.
NO -Go to step 10.
- Do the gauge control module input test (see
GAUGE CONTROL MODULE INPUT TEST
).
Are all inputs OK?
YES -Replace the gauge control module (see GAUGE CONTROL MODULE REPLACEMENT ).
NO -Repair the faulty input, then recheck the DTCs.
- Turn the ignition switch to LOCK (0).
- Remove the gauge control module but leave it connected, then turn the ignition switch to ON (II).
- Measure the voltage between body ground and gauge control module 32P connector terminals No. 15 and No. 16 individually.Fig 1: Measuring Voltage Between Body Ground And Gauge Control Module 32P Connector Terminals No. 15 And No. 16
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there battery voltage?
YES -Go to step 13.
NO -Check the No. 1 (15 A) and the No. 22 (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. 1 and No. 5 individually.Fig 2: Measuring Voltage Between Body Ground And Gauge Control Module 32P Connector Terminals No. 1 And No. 5
Courtesy of AMERICAN HONDA MOTOR CO., INC.
Is there less than 0.2 V?
YES -Go to step 14.
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 Q (16P).
- Check for continuity between under-dash fuse/relay box connector Q (16P) terminal No. 3 and gauge control module 32P connector terminal No. 17.Fig 3: Checking Continuity Between Under-Dash Fuse/Relay Box Connector Q (16P) Terminal No. 3 And Gauge Control Module 32P Connector Terminal No. 17
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.
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.