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 B2A10-14: Brake Light Drive Relay Circuit Malfunction
NOTE: Before you troubleshoot, review the general troubleshooting information - Refer to: How to Troubleshoot the Adaptive Cruise Control (ACC) and How to Troubleshoot the Collision Mitigation Braking System (CMBS) .
- VSA system DTCs check
-1. Turn the vehicle to the ON mode.
- 2. Check for VSA system DTCs with the HDS.
DTC Description DTC Freeze Frame Are any DTCs indicated?
YES
Go to the indicated DTC's troubleshooting .
NO
Go to step 2.
- Problem verification
-1. Clear the DTC with the HDS.
- 2. Turn the vehicle to the OFF (LOCK) mode, then the ON mode.
- 3. Select Integrated Driver Support System from the DRIVING SUPPORT menu, then enter ACC RELAY from the FUNCTION TEST menu.
- 4. Do the brake light relay function test with the HDS.
- 5. Check for DTCs with the HDS.
Is DTC B2A10-14 indicated?
YES
The failure is duplicated. Go to step 3.
NO
Intermittent failure, the system is OK at this time. Refer to intermittent failures troubleshooting - Refer to: How to Troubleshoot the Adaptive Cruise Control (ACC) or How to Troubleshoot the Collision Mitigation Braking System (CMBS) . If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the Freeze data/on-board snapshot.
- Multipurpose camera unit check (update)
-1. Update the multipurpose camera unit if it does not have the latest software.
- 2. Turn the vehicle to the OFF (LOCK) mode, then the ON mode.
- 3. Select Integrated Driver Support System from the DRIVING SUPPORT menu, then enter ACC RELAY from the FUNCTION TEST menu.
- 4. Do the brake light relay function test with the HDS.
- 5. Check for DTCs with the HDS.
Is DTC B2A10-14 indicated?
YES
Check for loose terminals in the multipurpose camera unit 20P connector. If the multipurpose camera unit was updated and the symptom/indication is still present, replace the multipurpose camera unit .
NO
Troubleshooting is complete. If any other DTCs are indicated, go to the indicated DTC's troubleshooting.
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.