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 brake pedal position (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 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 Sunshade - Left (DH6)
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
* Ignition ON, observe the scan tool Brake Switch parameter. The reading should be between Inactive/Active and change when the brake pedal is pushed or released.
* Ignition ON, perform the Brake Lamp Command test. The brake lamps should be ON/OFF.
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 5 ohms between the low reference circuit terminal C and ground.
• If greater than the specified range, test the low reference circuit for an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module.
3. Ignition ON, command the Brake Lamp Command test with a scan tool. The brake lamps should turn ON and OFF when changing between the commanded states.
• If the brake lamps did not turn ON and OFF replace the K9 Body Control Module.
Center High Mounted Brake Lamp Malfunction
1. Ignition OFF, disconnect the harness connector at the E6 Center High Mounted Brake Lamp.
2. Test for less than 5 ohms between the E6 Center High Mounted Brake Lamp ground circuit harness connector terminal 1 and ground.
• If greater than the specified value, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the E6 Center High Mounted Brake Lamp control circuit harness connector terminal 2 and ground.
4. Command the Center Brake Lamp Command test 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 Body Control Module.
• 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 Body Control Module.
5. If all circuits test normal, replace the E6 Center High Mounted Brake Lamp.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
Control Module References Control Module References for BCM replacement, setup and programming