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Stop Lamps Malfunction




Stop Lamps Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions Diagnostic Procedure Instructions provides an overview of each diagnostic category.

Diagnostic Fault Information






Circuit/System Description

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 V 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 voltage to the stop lamp control circuit and center high mounted stop lamp control circuit. When the control circuit is energized the stop lamps are illuminated.

Reference Information
Schematic Reference

Exterior Lights Schematics Exterior Lights Schematics
Connector End View Reference

Component Connector End Views Connector End Views By Name
Description and Operation

Exterior Lighting Systems Description and Operation Exterior Lighting Systems
Electrical Information Reference

* Circuit Testing Circuit Testing
* Connector Repairs Connector Repairs
* Testing for Intermittent Conditions and Poor Connections Testing for Intermittent Conditions and Poor Connections
* Wiring Repairs Wiring Repairs

Scan Tool Reference

Control Module References Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, observe the scan tool Brake Pedal Position Sensor parameter while applying and releasing the brake pedal. The value should be 0.2 V with the pedal pressed and 0 V with the pedal released.

• If the value does not change, refer to the Brake Pedal Position Sensor Malfunction.

2. Observe function of the E5L stop lamp- left while commanding the Left Brake Lamp ON and OFF with a scan tool. The E5L stop lamp- left should turn ON and OFF when changing between the selected states.

• If the E5L stop lamp- left is always ON or always OFF, refer to Left Brake Lamp Malfunction.

3. Observe function of the E5R stop lamp- right while commanding the Right Brake Lamp ON and OFF with a scan tool. The E5R stop lamp- right should turn ON and OFF when changing between the selected states.

• If the E5R stop lamp- right is always ON or always OFF, refer to Right Brake Lamp Malfunction.

4. Observe function of the E6 center high mounted stop lamp while commanding the Center Brake Lamp ON and OFF with a scan tool. The E6 center high mounted stop lamp should turn ON and OFF when changing between the selected states.

• If the E6 center high mounted stop lamp is always ON or always OFF, refer to Center High Mount Stop Lamp Malfunction.

Circuit/System Testing

Brake Pedal Position Sensor Malfunction
1. Ignition OFF, disconnect the harness connector at the B22 brake pedal position sensor.
2. Ignition OFF, test for less than 30 ohm between the low reference circuit terminal C and ground.

• If greater than the specified range, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.

3. Ignition ON, test for 4.8-5.2 V between the 5 V reference circuit terminal A and ground.

• If less than the specified range, test the 5 V reference circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
• If greater than the specified range, test the 5 V reference circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.

4. Verify that the scan tool Brake Pedal Position Sensor parameter is less than 0.3 V.

• If greater than the specified range, test the signal circuit terminal B for a short to voltage. If the circuit tests normal, replace the K9 BCM.

5. Connect a 3 A fused jumper wire between the 5 V reference circuit terminal A and the signal circuit terminal B. Verify that the scan tool Brake Pedal Position Sensor parameter is 4.8-5.2 V

• If less than the specified range, test the signal circuit for short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.

6. If all circuits test normal, test or replace the B22 brake pedal position sensor.

Left Brake Lamp Malfunction
1. Ignition OFF, disconnect the X1 harness connector at the E5E tail lamp-left.
2. Test for less than 30 ohm between the ground circuit terminal C and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal A and ground.
4. Ignition ON, command the Left Brake Lamp ON and OFF with a scan tool, the test lamp should turn ON and OFF when changing between the commanded states.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.

5. If all circuits test normal, test or replace the E5E tail lamp-left.

Right Brake Lamp Malfunction
1. Ignition OFF, disconnect the X1 harness connector at the E5F tail lamp-right.
2. Test for less than 30 ohm between the ground circuit terminal C and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal A and ground.
4. Ignition ON, command the Right Brake Lamp ON and OFF with a scan tool, the test lamp should turn ON and OFF when changing between the commanded states.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.

5. If all circuits test normal, test or replace the E5F tail lamp-right.

Center High Mount Stop Lamp Malfunction
1. Ignition OFF, disconnect the harness connector at the E6 center high mounted stop lamp.
2. Test for less than 30 ohm between the ground circuit terminal B and ground.

• If greater than the specified value, test the ground circuit for an open/high resistance.

3. Connect a test lamp between the control circuit terminal A and ground.
4. Ignition ON, command the Center Brake Lamp ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the K9 BCM.
• If the test lamp is always OFF, test the control circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the K9 BCM.

5. If all circuits test normal, replace the E6 center high mounted stop lamp.

Repair Instructions

Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.

* Brake Pedal Position Sensor Replacement
* Brake Pedal Position Sensor Calibration
* Tail Lamp Replacement Service and Repair
* High Mount Stop Lamp Replacement Service and Repair
* Control Module References Control Module References for BCM replacement, programming and setup

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