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 (BPP) sensor is used to sense the action of the driver application of the brake pedal. The BPP 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 BPP 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 tail/stop and turn signal lamp control circuits and the center high mounted stop lamp control circuit illuminating the stop lamps.
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 (Programming and Relearning) for scan tool information
Circuit/System Verification
1. Ignition ON, observe the scan tool Brake Applied Output Signal parameter as you apply and unapply the brake pedal. The reading should cycle between OFF and ON as the brake pedal is applied and released.
• If the reading does not change as the brake pedal is applied and released, refer to Brake Pedal Position (BPP) Sensor Malfunction.
2. Command the Brake Lamp Command ON and OFF with a scan tool. The stop lamps should turn ON and OFF when changing between the commanded states.
• If the stop lamps do not illuminate when commanded, refer to Stop Lamps Malfunction.
3. Command the Center Brake Lamp Command Test ON and OFF with a scan tool. The center high mounted stop lamp should turn ON and OFF when changing between the commanded states.
• If the center high mounted stop lamp does not illuminate when commanded, refer to Center High Mounted Stop Lamp Malfunction.
Circuit/System Testing
Brake Pedal Position (BPP) Sensor Malfunction
1. Ignition OFF, disconnect the harness connector at the B22 BPP sensor.
2. Ignition OFF, test for less than 5 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. Ignition ON, verify that a test lamp illuminates between B+ and the low reference circuit terminal C.
• If the test lamp does not illuminate, test the low reference circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 BCM.
4. 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.
5. Verify the scan tool BPP Sensor parameter is less than 1 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.
6. Install a 3 A fused jumper wire between the signal circuit terminal B and the 5 V reference circuit terminal A. Verify the scan tool BPP Sensor parameter is greater than 4 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.
7. If all circuits test normal, test or replace the B22 BPP sensor.
Stop Lamps Malfunction
1. Ignition OFF, disconnect the harness connector at the appropriate E5 stop lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5 ohm between the ground circuit terminal 1 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 3 and ground.
4. Command the Brake Lamp Command 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 E5 stop lamp.
Center High Mounted Stop Lamp Malfunction
1. Ignition OFF, disconnect the harness connector at the E6 center high mounted stop lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohm between the ground circuit terminal 2 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 1 and the ground circuit terminal 2.
4. Command the Center Brake Lamp Command Test 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.
* High Mount Stop Lamp Replacement (Service and Repair)
* Brake Pedal Position Sensor Replacement ()
* Tail Lamp Replacement - Inboard (Tail Lamp Replacement - Inboard)
* Tail Lamp Replacement - Outboard (Tail Lamp Replacement - Outboard)
* Control Module References (Programming and Relearning) for BCM replacement, setup, and programming