Diagnostic Instructions
| • | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. |
| • | Review Strategy Based Diagnosis for an overview of the diagnostic approach |
| • | Diagnostic Procedure Instructions provides an overview of each diagnostic category |
Diagnostic Fault Information
Circuit | Short to Ground | Open/High Resistance | Short to Voltage | Signal Performance |
|---|---|---|---|---|
Tail/Stop and Turn Signal Lamp Control -- Left | 1 | 1 | 1 | -- |
Tail/Stop and Turn Signal Lamp Control -- Right | -- | 1 | -- | -- |
CHMSL Control | 1 | 1 | 1 | -- |
Tail/Stop and Turn Signal Lamp Ground -- Left | -- | 1 | -- | -- |
Tail/Stop and Turn Signal Lamp Ground -- Right | -- | 1 | -- | -- |
CHMSL Ground | -- | 1 | -- | -- |
1. Stop Lamps Malfunction | ||||
Circuit/System Description
The BCM controls the stop lamps based on the input from the Brake Pedal Position Sensor (BPPS). When the BCM detects the brake pedal is depressed, B+ is applied to the stop lamp switch signal circuit and both stop/turn lamp supply voltage circuits, illuminating the center high mount stop lamp (CHMSL) and both stop lamps.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Exterior Lighting Systems Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, verify DTC C0277, C0278, C0283, or C0870 is not set.
- With the brake pedal depressed, verify the stop lamps and CHMSL are illuminated.
| ⇒ | If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle. |
| ⇒ | If the CHMSL does not illuminate, refer to CHMSL Malfunction. |
| ⇒ | If one or more of the stop lamps do not illuminate, refer to Stop Lamp Malfunction. |
Circuit/System Testing
CHMSL Malfunction
- Ignition OFF, disconnect the harness connector at the CHMSL.
- Test for less than 10 ohms between the ground circuit terminal B and ground.
- Connect a test lamp between the signal circuit terminal A and ground.
- Ignition ON, verify the test lamp turns ON and OFF when pressing and releasing the brake pedal.
- If all circuits test normal, test or replace the CHMSL.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | If the test lamp is always ON, test the signal circuit for a short to voltage. If the circuit tests normal, replace the BCM. |
| ⇒ | 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. |
Stop Lamp Malfunction
- Ignition OFF, disconnect the harness connector at the appropriate stop lamp bulb.
- Test for less than 10 ohms between the ground circuit terminal G and ground.
- connect a test lamp between the control circuit terminal A and ground.
- Ignition ON, verify the test lamp turns ON and OFF when pressing and releasing the brake pedal.
- If all circuits test normal, test or replace the appropriate stop lamp bulb.
| ⇒ | If greater than the specified range, test the ground circuit for an open/high resistance. |
| ⇒ | 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. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for BCM replacement, setup, and programming |
