A burned-out or faulty brake light bulb or LED assembly.; Corroded, loose, or damaged bulb socket contacts.; A failed brake pedal position switch (also called the stop lamp switch).; Damaged or chafed wiring in the brake lamp circuit, often near the pedal or through the trunk hinge.; A blown fuse that supplies power to the brake lamp circuit.; A faulty body control module (BCM) or rear electronic module, though this is less common.; Water intrusion into a tail light housing causing a short or high resistance.

DTC codes / B02xx · Airbags, seats, doors, lights and comfort systems / B0235

B0235Brake Lamp Circuit

Q: What does code B0235 mean?

Brake Lamp Circuit. B0235 is a body code that indicates the brake lamp circuit has a fault, meaning the computer has detected an abnormal condition in the wiring or components that illuminate the rear brake lights when you press the pedal. The body control module (BCM) monitors the circuit for expected voltage or current when the brake pedal is applied and released, and it sets this code when the signal does not match the expected pattern.

B0235 is a body code that indicates the brake lamp circuit has a fault, meaning the computer has detected an abnormal condition in the wiring or components that illuminate the rear brake lights when you press the pedal. The body control module (BCM) monitors the circuit for expected voltage or current when the brake pedal is applied and released, and it sets this code when the signal does not match the expected pattern.

SystemBody

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaAirbags, seats, doors, lights and comfort systems

Symptoms you may notice

The brake warning light or a specific lamp-out indicator may illuminate on the dashboard.
One or both rear brake lights may fail to illuminate when the brake pedal is pressed.
The brake lights may stay on continuously even when the pedal is released.
The cruise control may become inoperative because it relies on the brake pedal switch signal.
The shift interlock may not release, preventing the gear selector from moving out of Park.
Often no symptoms besides the warning light, especially if the fault is intermittent.

Common causes, most likely first

A burned-out or faulty brake light bulb or LED assembly.
Corroded, loose, or damaged bulb socket contacts.
A failed brake pedal position switch (also called the stop lamp switch).
Damaged or chafed wiring in the brake lamp circuit, often near the pedal or through the trunk hinge.
A blown fuse that supplies power to the brake lamp circuit.
A faulty body control module (BCM) or rear electronic module, though this is less common.
Water intrusion into a tail light housing causing a short or high resistance.

How to diagnose and fix it

Verify the complaint by pressing the brake pedal and observing all rear brake lights, including the center high-mounted stop lamp.
Check the brake lamp fuse in the underhood or interior fuse box and replace it if blown.
Inspect each brake light bulb and socket for corrosion, damage, or incorrect bulb type, and replace faulty components.
Test the brake pedal switch for continuity and proper adjustment using a multimeter, and replace it if defective.
Inspect the wiring harness from the switch to the rear lights for chafing, pinched wires, or corrosion at connectors.
Clear the code and perform a road test to confirm the repair, monitoring live data for the brake lamp circuit if available.
If the code persists, consult the factory service information for specific BCM diagnostics and circuit tests.

Before you replace the brake pedal switch

A common oversight is replacing the brake pedal switch when the actual problem is a corroded bulb socket or a chafed wire in the trunk hinge area, so always inspect the entire circuit first.
Some vehicles use a single filament bulb for both tail and brake lights with a dual-intensity signal, and a poor ground at the socket can cause the brake light to back-feed and illuminate dimly, setting this code.
The BCM may set B0235 even when the brake lights work normally if the switch signal is intermittent, so wiggle-testing the harness while watching live data can reveal the fault.
Aftermarket LED bulbs can draw less current than expected and trigger a bulb-out warning or this code, so verify that any replacement bulbs meet the vehicle's electrical requirements.
The brake pedal switch often has two internal switches: one for the brake lights and one for the cruise control or shift interlock, and only the brake light portion may fail, causing this code without affecting other functions.

Can I keep driving with B0235?

If the brake lights are not working at all, do not drive the vehicle on public roads because other drivers cannot see your braking intention, which is a serious safety hazard. If only the warning light is on but the brake lights function normally, you may drive cautiously to a repair shop, but avoid relying on cruise control until the fault is fixed.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.