DTC: C0023-12 (2016 2017 2018)

DTC C0023-12  : Brake Diag Circuit ON Failure

NOTE: Before You Troubleshoot, Review The General Troubleshooting Information .

DTCs (VSA)

1. Brake light relay check

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Check the brake lights without pressing the brake pedal.

   Are the brake lights on?

   YES 

   Replace the brake light relay.

   NO 

   Go to step 2.

2. Shorted wire check (BRAKE LAMP line) 1

   -1. Turn the vehicle to the ON mode.

   - 2. Check the brake lights without pressing the brake pedal.

   Are the brake lights on?

   YES 

   Go to step 3.

   NO 

   Go to step 4.

3. Shorted wire check (BRAKE LAMP line) 2

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Disconnect the following connector.

   VSA modulator-control unit 38P connector

   - 3. Turn the vehicle to the ON mode.

   - 4. Check the brake lights without pressing the brake pedal.

   Are the brake lights on?

   YES 

   Repair a short to body ground in the BRAKE LAMP wire between the VSA modulator-control unit and the brake light relay.

   NO 

   The BRAKE LAMP wire is OK. Go to step 7.

4. Problem verification

   -1. Clear the DTC with the HDS.

   - 2. Turn the vehicle to the OFF (LOCK) mode, then the ON mode.

   - 3. Press the brake pedal for 3 seconds or more.

   - 4. Check for DTCs with the HDS.

   DTC Description	DTC	Freeze Frame
   C0023-12 Brake Diag Circuit ON Failure

   Is DTC C0023-12 indicated?

   YES 

   The failure is duplicated. Go to step 5.

   NO 

   Intermittent failure, the wire between the VSA modulator-control unit and the brake light relay is OK at this time.

5. Open wire check (STOP SW line)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Jump the SCS line with the HDS, and wait more than 1 minute.

   - 3. Disconnect the following connectors.

   Brake pedal position switch 4P connector

   PCM connector A (51P)

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

   Test condition	Vehicle OFF (LOCK) mode
   	Brake pedal position switch 4P connector: disconnected
   	PCM connector A (51P): disconnected
   Test point 1	Brake pedal position switch 4P connector No. 1
   Test point 2	PCM connector A (51P) No. 25 - Refer to: PCM Connector for Inputs and Outputs (9-Speed A/T) (2019 2020 2021) or PCM Connector for Inputs and Outputs (9-Speed A/T) (2016 2017 2018) PCM Connector for Inputs and Outputs (6-Speed A/T) (2016 2017 2018 2019 2020) or

   Courtesy of HONDA, U.S.A., INC.

   Is there continuity?

   YES 

   The STOP SW wire is OK. Go to step 6.

   NO 

   Repair an open in the wire between the PCM and the brake pedal position switch.

6. PCM check (substitution)

   -1. Reconnect the following connectors.

   Brake pedal position switch 4P connector

   PCM connector A (51P)

   - 2. Substitute a known-good PCM.

   - 3. Clear the DTC with the HDS.

   - 4. Turn the vehicle to the OFF (LOCK) mode, then the ON mode.

   - 5. Press the brake pedal for 3 seconds or more.

   - 6. Check for DTCs with the HDS.

   DTC Description	DTC	Freeze Frame
   C0023-12 Brake Diag Circuit ON Failure

   Is DTC C0023-12 indicated?

   YES 

   Go to step 7.

   NO 

   If the PCM was substituted, replace the original PCM - Refer to:

   PCM Removal and Installation (9-Speed A/T (2019 2020 2021) or

   PCM Removal and Installation .

7. VSA modulator-control unit check (substitution)

   -1. Turn the vehicle to the OFF (LOCK) mode.

   - 2. Reconnect the following connector.

   VSA modulator-control unit 38P connector (if disconnected)

   - 3. Substitute a known-good VSA modulator-control unit.

   - 4. Turn the vehicle to the OFF (LOCK) mode, then the ON mode.

   - 5. Press the brake pedal for 3 seconds or more.

   - 6. Check for DTCs with the HDS.

   DTC Description	DTC	Freeze Frame

   Is DTC C0023-12 indicated?

   YES 

   Check for loose terminals and poor connections in the VSA modulator-control unit 38P connector. If they are OK, replace the VSA Modulator-Control Unit. Refer to:

   Replace The VSA Modulator-Control Unit .

   NO 

   Troubleshooting is complete. If any other DTCs are indicated, go to the indicated DTCs troubleshooting.