Stop Lamps
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The brake pedal position sensor is used to sense the action of the driver application of the brake pedal. The brake pedal position sensor provides an analog voltage signal that will increase as the brake pedal is applied. The body control module (BCM) provides a low reference signal and a 5-volt reference voltage to the brake pedal position sensor. When the variable signal reaches a voltage threshold indicating the brakes have been applied, the BCM will apply battery positive voltage to the stop lamps, transmission control module (TCM), engine control module (ECM), and stop lamp relay coil side. When the stop lamp relay receives battery voltage from the BCM, the relay coil is energized and the stop lamp relay switch contacts close applying battery voltage through the STOP LP fuse to illuminate the center high mounted stop lamp (CHMSL).
I'd say you have more then a bad fuse ,just reading how the brake lights function .You should have it hooked up to a professional grade scan tool ,one that can check for DTC'S - diagnostic trouble codes in the BCM - body control module !
- Install a scan tool.
- Turn ON the ignition, with the engine OFF.
- With a scan tool, observe the Brake Pedal Position Sensor parameter in the data list for the body control module (BCM).
- Apply and release the brake pedal.
Does the scan tool display a change in the voltage?
DTC B3903 Stop Lamp Relay Circuit
DTC C0277 Brake Pedal Position Sensor Circuit
DTC C0278
Did you perform the Diagnostic System Check - Vehicle?
Go to Step 2
Go to Diagnostic System Check - Vehicle
2
- Install a scan tool.
- Turn ON the ignition, with the engine OFF.
Does the scan tool display DTC C0278 00?
Go to Step 3
Go to Testing for Intermittent Conditions and Poor Connections
3
Recalibrate the brake position sensor.
Circuit Description
DTC C0870
The body control module (BCM) applies a ground through the brake sensor reference low circuit to the brake pedal position (BPP) sensor. The BCM supplies a 5-volt reference through the brake sensor reference voltage circuit to the brake position sensor. When the brake pedal is being applied, the BPP sensor then sends a variable voltage signal through the brake sensor signal circuit to the BCM.
Circuit/System Verification
- Ignition ON, observe the scan tool Brake Lamp Cmd. parameter as you apply and unapply the brake pedal. The parameter should change between OFF and ON as the brake pedal is applied and released.
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If the parameter does not change as the brake pedal is applied and released, refer to Brake Pedal Position Sensor (BPPS) Malfunction.
- With a scan tool, command the LR Stop/Turn Signal Lamp ON and OFF. The LR turn signal should turn ON and OFF when changing between the commanded states.
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If the LR stop lamp does not illuminate when commanded, refer to Stop Lamps Malfunction.
- With a scan tool, command the RR Stop/Turn Signal Lamp ON and OFF. The RR turn signal should turn ON and OFF when changing between the commanded states.
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If the RR stop lamp does not illuminate when commanded, refer to Stop Lamps Malfunction.
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