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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 Instructionsprovides an overview of each diagnostic category.

Diagnostic Fault Information






Circuit/System Description

North America

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 right and left stop lamp control circuits, transmission control module (TCM), engine control module (ECM), and center high mounted stop lamp (CHMSL) control circuit.

European

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 stop lamp relay coil side control circuit, transmission control module (TCM), engine control module (ECM), and center high mounted stop lamp (CHMSL). 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 from the STOP LAMPS fuse to illuminate the rear stop lamps and trailer stop lamps.

Diagnostic Aids

The stop lamps will not illuminate unless the ignition is in the ON position. For more detailed information concerning stop lamp operation, refer to Exterior Lighting Systems Description and Operation Exterior Lighting Systems.

Reference Information
Schematic Reference

Exterior Lights Schematics Exterior Lights Schematics
Connector End View Reference

Component Connector End Views Connector Views
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 Referencesfor scan tool information

Circuit/System Verification

1. Ignition ON, observe the scan tool Brake Applied Output Signal parameter while pressing and releasing the brake pedal. The parameter should change between ON and OFF as the brake pedal is applied and released.

• If the parameter does not change between the selected states, refer to the Brake Pedal Position Sensor Malfunction.

2. Observe the left and right stop lamps while applying and releasing the brake pedal. The stop lamps should turn ON and OFF as the brake pedal is applied and released.

• If the left or right stop lamps do not change between the selected states, refer to the Stop Lamp Malfunction.

3. Observe the center high mount stop lamp while pressing and releasing the brake pedal. The center high mount stop lamp should turn ON and OFF as the brake pedal is applied and released.

• If the center high mount stop lamp does not change between the selected states, 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 brake pedal position sensor.
2. Ignition ON, verify that a test lamp does not illuminate between the low reference circuit terminal listed below and ground:

* Terminal 2 - LHD
* Terminal 1 - RHD

• If the test lamp illuminates, test the low reference circuit for a short to voltage. If the circuit tests normal, replace the BCM.

3. Ignition ON, test for 4.8 V and 5.2 V between the 5 V reference circuit terminal listed below and ground:

* Terminal 1 - LHD
* Terminal 2 - RHD

• 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 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 BCM.

4. If all circuits test normal, replace the brake pedal position sensor.

Stop Lamp Malfunction - North America
1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Verify that a test lamp illuminates between the BCM 5 fuse B+ circuit terminal 1 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. Verify that a test lamp illuminates between the BCM 6 fuse B+ circuit terminal 3 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

4. Ignition OFF, reconnect the X4 harness connector at the BCM.
5. Disconnect the harness connector at the appropriate tail lamp.
6. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohm between the ground circuit terminal C and ground.

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

7. Connect a test lamp between the control circuit terminal B and ground.
8. Ignition ON, turn the appropriate stop lamp ON and OFF by pressing and releasing the brake pedal. 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 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 BCM.

9. If all circuits test normal, replace the tail lamp.

Stop Lamp Malfunction - European
1. Ignition OFF, disconnect the X4 harness connector at the BCM.
2. Ignition ON, verify that a test lamp illuminates between the BCM 5 fuse B+ circuit terminal 1 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

3. Ignition ON, verify that a test lamp illuminates between the BCM 6 fuse B+ circuit terminal 3 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance.

4. Ignition OFF, reconnect the X4 harness connector at the BCM.
5. Disconnect the stop lamp relay.
6. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohm between the ground circuit terminal 85 and ground.

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

7. Ignition ON, verify that a test lamp does not illuminate between the control circuit terminal 30 and ground.

• If the test lamp illuminates, test the control circuit for a short to voltage.

8. Verify that a test lamp illuminates between the B+ circuit terminal 87 and ground.

• If the test lamp does not illuminate, test the B+ circuit for a short to ground or an open/high resistance. If the circuit tests normal and the B+ circuit fuse is open, test the relay control circuit terminal 86 for a short to ground. If the circuit tests normal, test or replace the stop lamp relay.

9. Connect a test lamp between the control circuit terminal 86 and the ground circuit terminal 85.
10. Ignition ON, turn the stop lamps ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the selected states.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the 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 BCM.

11. Disconnect the harness connector at the appropriate tail lamp.
12. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohm between the ground circuit terminal H and ground.

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

13. Connect a test lamp between the control circuit terminal B and the ground circuit terminal H.
14. Ignition ON, turn the stop lamps ON and OFF by applying and releasing the brake pedal. 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 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 BCM.

15. If all circuits test normal, replace the tail lamp.

Center High Mounted Stop Lamp Malfunction
1. Ignition OFF, disconnect the harness connector at the center high mounted stop lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohm between the ground circuit terminal B 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 the ground circuit terminal B.
4. Ignition ON, turn the stop lamps ON and OFF by applying and releasing the brake pedal. The test lamp should turn ON and OFF when changing between the selected states.

• If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the 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 BCM.

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

Repair Instructions

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

* High Mount Stop Lamp Replacement (Sedan, V-Series) High Mount Stop Lamp Replacement (Sedan, V-Series)High Mount Stop Lamp Replacement (Wagon) High Mount Stop Lamp Replacement (Wagon)High Mount Stop Lamp Replacement (Coupe) High Mount Stop Lamp Replacement (Coupe)
* Tail Lamp Replacement (Sedan, V-Series) Tail Lamp Replacement (Sedan, V-Series)Tail Lamp Replacement (Wagon) Tail Lamp Replacement (Wagon)Tail Lamp Replacement (Coupe) Tail Lamp Replacement (Coupe)
* Relay Replacement (Attached to Wire Harness) Relay Replacement (Attached to Wire Harness)Relay Replacement (Within an Electrical Center) Relay Replacement (Within an Electrical Center)
* Brake Pedal Position Sensor Replacement
* Control Module References Control Module Referencesfor BCM replacement, setup, and programming

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