Brake Warning Indicator Inoperative

BRAKE WARNING INDICATOR INOPERATIVE

Brake Warning Indicator Inoperative:

POSSIBLE CAUSES
- (Z420) Brake fluid level sensor ground circuit open
- (B25) Park brake switch sense circuit open
- (B20) Brake fluid level sense circuit open
- Park brake switch
- Brake fluid level sensor
- Anti-lock brakes module
- Instrument cluster

DIAGNOSTIC TEST

1. FAULT LOCATION

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

Q: Is the Brake warning indicator only inoperative using the Park Brake?

YES: Go To 2
NO: Go To 4

2. PARK BRAKE SWITCH




Disconnect the Park Brake Switch harness connector.
Connect a jumper wire between the (B25) Park Brake Switch Sense circuit and ground.
Turn the ignition on.
Observe the BRAKE indicator.

Q: Did the BRAKE indicator illuminate?

YES: Replace the Park Brake Switch. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 3

3. (B25) PARK BRAKE SWITCH SENSE CIRCUIT OPEN




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

Q: Is the resistance above 5.0 ohms?

YES: Repair the (B25) Park Brake Switch Sense circuit for an open. 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

4. BRAKE FLUID LEVEL SENSOR




Turn the ignition off.
Disconnect the Brake Fluid Level Sensor harness connector.
Connect a jumper wire between cavity 1 and cavity 2. Turn the ignition on.

Q: Does the Brake warning indicator illuminate?

YES: Replace the Brake Fluid Level Sensor. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 5

5. (Z420) BRAKE FLUID LEVEL SENSOR GROUND CIRCUIT OPEN




Turn the ignition off.
Disconnect the Brake Fluid Level Sensor harness connector.
Measure the resistance between ground and the (Z420) Brake Fluid Level Sensor Ground circuit.

Q: Is the resistance above 5.0 ohms?

YES: Repair the (Z420) Brake Fluid Level Sensor Ground circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 6

6. (B20) BRAKE FLUID LEVEL SENSE CIRCUIT OPEN




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

Q: Is the resistance above 5.0 ohms?

YES: Repair the (B20) Brake Fluid Level Sensor Sense circuit for an open. Perform BODY VERIFICATION TEST - VER 1. Body Verification Test
NO: Go To 7

7. INSTRUMENT CLUSTER




Turn the ignition off.
Disconnect the Anti-lock Brakes Module harness connector.
Connect a jumper wire between the (B25) Brake Fluid Level Sensor Sense circuit and ground.
With the DRBIII(R) in Inputs/Outputs, read the Brake Fluid Level Sensor state.

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

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