Volt

Brake Warning Indicator Malfunction

The brake fluid level switch monitors the level of brake fluid in the master cylinder. When the electronic brake control module (EBCM) sees the brake fluid level switch input grounded, it sends a serial data message to the instrument panel cluster to turn ON the Red Brake Warning indicator.

Schematic Reference

Hydraulic Brake Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Brake Warning System Description and Operation

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

1. Verify the brake fluid is at or above the minimum level.

⇒	If low, refer to Brake Fluid Loss .

2. Command the instrument panel cluster lamp test with a scan tool, the warning indicator should turn ON.

⇒	If the red brake warning indicator does not illuminate, replace the P16 Instrument Cluster.

3. Vehicle in Service Mode, observe the scan tool Brake Fluid Level Sensor parameter. The reading should be OK.

1. Vehicle OFF, disconnect the harness connector at the B20 Brake Fluid Level Switch.
2. Test for less than 5 Ω between the ground circuit terminal B and ground.

⇒	If greater than the specified range, test the ground circuit for an open/high resistance.

3. Vehicle in Service Mode, verify the scan tool Brake Fluid Level Sensor parameter is OK.

⇒	If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the K17 Electronic Brake Control Module.

Note: The parameter may take up to 60 seconds to switch from OK to Low.

4. Install a 3 A fused jumper wire between the signal circuit terminal A and ground circuit terminal B. Verify the scan tool Brake Fluid Level Sensor parameter is Low.

⇒	If not the specified value, test the signal circuit for 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.

Static Test

1. Vehicle OFF, disconnect the harness connector at the B20 Brake Fluid Level Switch.
2. Test for infinite resistance between the ground terminal B and the signal terminal A with the switch in the open position.

⇒	If less than the specified value, replace the B20 Brake Fluid Level Switch.

3. Test for less than 5 Ω between the signal terminal A and ground terminal B with the switch in the closed position.

⇒	If greater than the specified range, replace the B20 Brake Fluid Level Switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.