Brake Pedal Position Sensor (Brake Switch) (BPP)
Group: Chassis and safety
The brake pedal switch or sensor turns on the brake lights and tells the computer the driver is braking. It affects cruise control, push-button start and the automatic transmission shift interlock.
Contents
What does the BPP sensor do?
The simplest ones are two-contact switches (one normally open for the brake lights and one normally closed for cruise control). Modern ones are position sensors that report how far the pedal is pressed. The computer compares the two signals: if they disagree, it disables cruise control and stores a code. Many vehicles with push-button start require you to press the brake to start the engine.
Where is it located?
On the brake pedal bracket under the dashboard, resting against the pedal arm.
Signal type and reference values
- Switch: 12 V at the brake light output when pressed; the other contact opens when pressed.
- Position sensor: 5 V, ground and a proportional signal, or a digital output.
Values are a guide only: always check the manufacturer's data for your vehicle.
Symptoms of a bad BPP sensor
How to test the BPP sensor step by step
- Ask someone to watch the brake lights while you press the pedal.
- On the scan tool, check that the computer sees the pedal pressed and released.
- Check the rubber pedal stop: if it falls out, the switch stays activated all the time.
- Measure continuity on both switch contacts in both positions.
- Some sensors need adjustment or calibration after replacement.
Trouble codes related to the BPP sensor
Frequently asked questions about the BPP sensor
Why does my cruise control not work?
What does code P0504 mean?
Updated September 25, 2026. Values are a guide only: always confirm them in the service manual for your engine.