Brake Warning Indicator Always On

BRAKE WARNING INDICATOR ALWAYS ON

Brake Warning Indicator Always On:

POSSIBLE CAUSES
- (B20) Brake fluid level sensor sense circuit short to ground
- (B25) Park brake switch sense circuit short to ground
- Brake fluid level sensor
- Park brake switch
- Anti-lock brakes module
- Instrument cluster

DIAGNOSTIC TEST

1. BRAKE FLUID LEVEL SENSOR

NOTE: Diagnose and repair any MIC, Brake, or Communication DTCs before proceeding with this test.




Disconnect the Brake Fluid Level Sensor harness connector.
Measure the resistance of the Brake Fluid Level Sensor between pin 1 and pin 2.

Q: Does the resistance measure less than 900 ohms?

YES: Replace the Brake Fluid Level Sensor. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 2

2. (B20) BRAKE FLUID LEVEL SENSOR SENSE CIRCUIT SHORT TO GROUND




Turn the ignition off.
Disconnect the Brake Fluid Level Sensor harness connector.
Disconnect the Anti-lock Brakes Module harness connector.
Measure the resistance between ground and the (B20) Brake Fluid Level Sensor Sense circuit.

Q: Is the resistance below 5.0 ohms?

YES: Repair the (B20) Brake Fluid Level Sensor Sense circuit for a short to ground. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 3

3. PARK BRAKE SWITCH




Turn the ignition off.
Disconnect the Park Brake Switch harness connector.
Turn the ignition on.
Observe the Brake warning indicator.

Q: Did the Brake warning indicator illuminate briefly and then turn off?

YES: Replace the Park Brake Switch. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 4

4. (B25) PARK BRAKE SWITCH SENSE CIRCUIT SHORT TO GROUND




Turn the ignition off.
Disconnect the Park Brake Switch harness connector.
Disconnect the Instrument Cluster C3 harness connector.
Measure the resistance between ground and the (B25) Park Brake Switch Sense circuit.

Q: Is the resistance below 5.0 ohms?

YES: Repair the (B25) Park Brake Switch Sense circuit for a short to ground. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 5

5. ANTI-LOCK BRAKES MODULE
Turn the ignition off.
Reconnect any harness connector(s) that were previously disconnected.
Turn the ignition on.
With the DRBIII(R) in Inputs/Outputs, read the Brake Fluid Level Sensor state.

Q: Does the DRBIII(R) display "Closed"?

YES: Replace the Anti-lock Brakes Module. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Replace and configure the Instrument Cluster. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test