Stop Lamps Malfunction
Stop Lamps Malfunction
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)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-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, center high mounted stop lamp (CHMSL), transmission control module (TCM), and engine control module (ECM). The stop lamps will not operate unless the ignition is in the ON position. Ground for the left rear stop lamps is provided at G400. Ground for the right rear stop lamps is provided by G402.
Diagnostic Aids
Important: 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 Description and Operation) .
Reference Information
Schematic Reference
Exterior Lights Schematics (Exterior Lights Diagram 1)
Connector End View Reference
Component Connector End Views (Connector Views)
Description and Operation
Exterior Lighting Systems Description and Operation (Exterior Lighting Systems Description and Operation)
Electrical Information Reference
* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)
Scan Tool Reference
Control Module References (Programming and Relearning)
Circuit/System Testing
Stop Lamps Malfunction
1. Ignition OFF, disconnect harness connector at the inoperative stop lamp.
2. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms of resistance between the ground circuit and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the stop lamp supply voltage circuit and ground.
4. Command the inoperative stop 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 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, replace the inoperative stop lamp.
High Mounted Stop Lamp Malfunction
1. Ignition OFF, disconnect the harness connector at the CHMSL.
2. Ignition OFF, exterior lamps OFF, test for less than 5.0 ohms of resistance 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 stop lamp switch signal circuit terminal A and ground circuit terminal B.
4. Ignition ON, apply the brake pedal ON and OFF. The test lamp should turn ON and OFF as the brake pedal is applied and released.
• If the test lamp is always OFF, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace the BCM.
• If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM.
5. If all circuits test normal, replace the CHMSL.
Repair Instructions
Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.
* High Mount Stop Lamp Replacement (Service and Repair)
* Tail Lamp Replacement (SKY) (Tail Lamp Replacement (SKY))Tail Lamp Replacement (Solstice) (Tail Lamp Replacement (Solstice))
* Tail Lamp Bulb Replacement (SKY) (Service and Repair)
* Control Module References (Programming and Relearning)for BCM replacement, setup, and programming