Brake Warning Indicator Malfunction
Brake Warning Indicator 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
Electronic brake control module (EBCM) monitors the brake fluid level in the brake fluid reservoir. When the fluid within the brake fluid reservoir is below the MIN level, contacts within the brake fluid level switch closes causing the voltage within the signal circuit to drop. The electronic brake control module (EBCM) will detect the voltage drop and will send a serial data message to the instrument cluster commanding the brake warning indicator to illuminate.
Reference Information
Schematic Reference
Hydraulic Brake Schematics [1][2]Electrical Diagrams
Connector End View Reference
Component Connector End Views Connector End Views By Name
Description and Operation
Brake Warning System Description and Operation Brake Warning System
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. Verify the fluid level within the brake master cylinder reservoir is above the MIN level.
• If not the specified condition, refer to Master Cylinder Reservoir Filling Master Cylinder Reservoir Filling.
2. Ignition ON, command the instrument cluster All Indicators ON and OFF with a scan tool, the brake warning indicator should turn ON and OFF while changing between the commanded states.
• If the brake warning indicator is always ON or always OFF, replace the instrument cluster.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the B20 Brake Fluid Level Switch.
2. Test for less than 10 ohms between the ground circuit terminal 2 and ground.
• If greater than the specified range, test the ground circuit for an open/high resistance.
3. Ignition ON, verify the scan tool Brake Fluid Level Sensor parameter is OK.
• If not the specified value, test the signal circuit terminal 1 for a short to ground. If the circuit tests normal, replace the K17 Electronic Brake Control Module.
4. Install a 3 A fused jumper wire between the signal circuit terminal 1 and the ground circuit terminal 2, verify the scan tool Brake Fluid Level Sensor parameter is Low.
• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K17 Electronic Brake Control Module.
5. If all circuits test normal, test or replace the B20 Brake Fluid Level Switch.
Repair Instructions
Perform the Diagnostic Repair Verification Verification Tests after completing the diagnostic procedure.
* Brake Fluid Level Indicator Switch Replacement Service and Repair
* Control Module References Programming and Relearning for EBCM and instrument panel cluster replacement, programming and setup