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 |
|---|---|---|---|---|
Park Brake Switch Signal | 1 | 1 | -- | -- |
Brake Fluid Level Switch Signal | -- | 2 | -- | -- |
Brake Fluid Level Switch Ground | -- | 2 | -- | -- |
1. Brake Fluid Switch Malfunction 2. Park Brake Switch Malfunction | ||||
Circuit/System Description
The instrument panel cluster (IPC) sees the brake fluid level switch input grounded and illuminates the red brake indicator. The electronic brake control module (EBCM) sees the park brake switch input grounded, it sends a serial data message to the IPC requesting illumination of the red brake indicator.
Reference Information
Schematic Reference
Connector End View Reference
Description and Operation
Brake Warning System Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
With the scan tool, select instrument panel special functions Lamp Test. Command the instrument panel indicator lights ON. Verify the red brake indicator lamp turns ON.
| ⇒ | If the brake lamp does not turn ON, check the Brake Warning Indicator Lamp Inoperative in Circuit/System Testing. |
| ⇒ | If the brake lamp does not turn OFF, check the Brake Warning Indicator Lamp Always ON in Circuit/System Testing. |
Circuit/System Testing (Brake Warning Indicator Always ON)
- With the scan tool, select instrument panel special functions Lamp Test. Command the instrument panel lamps OFF. Verify brake lamp turns OFF.
- Disconnect the park brake switch terminal 1. With a scan tool, observe the Park Brake Switch parameter. Verify parameter is reading ON.
- Test the park brake switch signal circuit for a short to ground.
- If all circuits test normal, test or replace the EBCM
| ⇒ | If the brake lamp does not turn OFF, replace the IPC. |
| ⇒ | If the parameter is OFF, replace the park brake switch. |
Circuit/System Testing (Brake Warning Indicator Inoperative)
- With the scan tool, select instrument panel special functions Lamp Test. Command the instrument panel lamps ON. Verify brake lamp turns ON.
- Release the park brake. Disconnect the brake fluid level switch terminal B Connect a 3-amp jumper wire between the signal circuit of the brake fluid level switch terminal B and the ground circuit of the brake fluid level switch terminal A . Ignition ON, verify the brake lamp is ON.
- Disconnect the park brake switch. Connect a 3-amp jumper wire between signal circuit of the park brake switch and ground. Ignition ON, verify the brake lamp is ON.
- If all circuits test normal, test or replace the park brake switch.
| ⇒ | If the brake lamp does not turn ON, replace the IPC. |
| ⇒ | If the brake lamp does not turn ON, test the signal circuit and ground circuit for a high resistance/open. If the circuit tests normal, replace the park brake booster fluid level switch. |
| ⇒ | If the brake lamp does not turn ON, test the signal circuit for a high resistance/open. If the circuit tests normal, replace the EBCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
| • | Control Module References for IPC, and EBCM replacement, setup, and programming |
