Honda HR-V: DTC B1931 Backup Control Unit No Response

DTC (Backup Control Unit)

NOTE: If you are troubleshooting multiple DTCs, be sure to follow the instructions in B-CAN System Diagnosis Test Mode A - Refer to: Body Electrical Troubleshooting - B-CAN System Diagnosis Test Mode A - Initial Communication and DTC Checks.

1. Problem verification.

1. Clear the DTCs with the HDS.

Clear DTCs

2. Open the driver's window all the way down, and close all the doors, then turn the vehicle to the OFF (LOCK) mode.
3. Remove all the keyless remotes from inside the vehicle. Hold one keyless remote outside of the opened driver's window at least 7.9 in (20 cm) away from the vehicle.
4. With holding the keyless remote outside of the opened driver's window, press the engine start/stop button, and wait for 30 seconds. Repeat this procedure a total of 5 times.
5. Check for DTCs with the HDS.

Is DTC B1931 indicated?

YES

Go to step 2.

NO

Intermittent failure, the system is OK at this time. Check for loose or poor connections.

2. Connector check.

1. Turn the vehicle to the OFF (LOCK) mode.
2. Check for loose connections in the engine start/stop switch 10P connector.

Is the connections OK?

YES

Go to step 3.

NO

Repair the poor connection of engine start/stop switch 10P connector, and then recheck the system.

3. Backup control unit SS1 (+), SS2 (-) lines check.

1.  Turn the vehicle to the ON mode, and keep pressing the engine start/stop button.
2.  Measure the voltage between test points 1 and 2.

Is there battery voltage when the engine start/stop button is pressed?

YES

Go to step 5.

NO

Go to step 4.

4. Engine start/stop switch check.

1. Turn the vehicle to the OFF (LOCK) mode.
2. Test the engine start/stop switch.

Is the engine start/stop switch OK?

YES

Repair an open or high resistance in the SS1 (+) and/or SS2 (-) wire(s).

NO

The SS1 (+) and SS2 (-) wires are OK. Replace the engine start/stop switch.

5. Engine start/stop switch SS SW VCONT line check.

1. Turn the vehicle to the OFF (LOCK) mode.
2. Turn the vehicle to the ON mode.
3. Measure the voltage between test points 1 and 2.

Is there battery voltage?

YES

Go to step 6.

NO

Go to step 8.

6. Shorted wire check (DIN/DOUT, DCK lines).

1. Turn the vehicle to the OFF (LOCK) mode.
2. Disconnect the following connectors.

Keyless access control unit connector B (36P)

Engine start/stop switch 10P connector

3. Check for continuity between test points 1 and 2 individually.

Is there continuity?

YES

Repair a short to ground in the wire.

NO

The DIN/DOUT and DCK wires are not shorted. Go to step 7.

7. Open wire check (DIN/DOUT, DCK lines).

1. Check for continuity between test points 1 and 2 respectively.

Is there continuity?

YES

The DIN/DOUT and DCK wires are OK. Replace the keyless access control unit.

NO

Repair an open or high resistance in the wire.

8. Shorted wire check (SS SW VCONT line).

1. Turn the vehicle to the OFF (LOCK) mode.
2. Disconnect the following connectors.

Keyless access control unit connector B (36P)

Engine start/stop switch 10P connector

3. Check for continuity between test points 1 and 2.

Is there continuity?

YES

Repair a short to ground in the wire.

NO

The SS SW VCONT wire is not shorted. Go to step 9.

9. Open wire check (SS SW VCONT line).

1. Check for continuity between test points 1 and 2.

Is there continuity?

YES

The SS SW VCONT wire is OK. Replace the keyless access control unit.

NO

Repair an open or high resistance in the wire.

READ NEXT: