Brake Warning Indicator Malfunction - Without Antilock Brake System
Diagnostic Instructions
Circuit/System Description
The instrument cluster turns ON the brake warning indicator for 5 s after ignition ON. The body control module (BCM) monitors the parking brake switch and brake fluid level switch and will request the instrument cluster via serial data to turn the brake warning indicator ON when the parking brake is applied or the brake fluid level is low.
Reference Information
Schematic Reference
Hydraulic Brake Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Hydraulic Brake System Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Inspect for proper brake fluid level. The fluid level should be above minimum level.
- Ignition ON, with a scan tool command the instrument cluster All Indicators test ON and OFF. Verify the brake warning indicator turns ON and OFF.
⇒ | If the brake warning indicator does not turn ON and OFF, replace the P16 Instrument Cluster. |
- Observe the scan tool BCM Park Brake Switch parameter while applying and releasing the handbrake. Verify the reading changes between Active and Inactive.
⇒ | If the parameter does not change between the specified values, refer to Park Brake Switch Malfunction. |
- Release the handbrake. Verify the brake warning indicator turns OFF.
⇒ | If the brake warning indicator does not turn OFF, refer to Brake Fluid Level Switch Malfunction. |
Circuit/System Testing
Note: Circuit/System Verification must be performed before Circuit/System Testing.
Park Brake Switch Malfunction
- Ignition OFF, disconnect the harness connector at the B80 Handbrake Switch.
- Inspect the B80 Handbrake Switch for physical damage and correct installation.
⇒ | If physical damage or incorrect installation is diagnosed, repair or replace the B80 Handbrake Switch. |
- Ignition ON, verify the scan tool BCM Handbrake Switch parameter is Inactive.
⇒ | If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the K9 Body Control Module. |
- Install a 3 A fused jumper wire between the signal circuit terminal A and ground.
- Verify the scan tool BCM Handbrake Switch parameter is Active.
⇒ | 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 K9 Body Control Module. |
- If all circuits test normal, test or replace the B80 Handbrake Switch.
Brake Fluid Level Switch Malfunction
- Ignition OFF, disconnect the harness connector at the B20 Brake Fluid Level Switch.
- Test for less than 10 Ω between the ground circuit terminal 2 and ground.
⇒ | If greater than the specified value, test the ground circuit for an open/high resistance. |
- Release the handbrake.
- Ignition ON, verify the brake warning indicator turns ON.
⇒ | If the indicator does not turn ON, test the signal circuit for a short to ground. If the circuit tests normal, replace the K9 Body Control Module. |
- Install a 3 A fused jumper wire between the signal circuit terminal 1 and ground.
- Verify the brake warning indicator turns OFF.
⇒ | If the indicator does not turn OFF, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the K9 Body Control Module. |
- If all circuits test normal, test or replace the B20 Brake Fluid Level Switch.
Component Testing
Park Brake Switch Test
- Ignition OFF, disconnect the harness connector at the B80 Handbrake Switch.
- Test for infinite resistance between the signal circuit terminal A and ground with the parking brake released.
⇒ | If less than the specified value, replace the B80 Handbrake Switch. |
- Test for less than 5 Ω between the signal circuit terminal A and ground c with the park brake applied.
⇒ | If greater than the specified value, replace the B80 Handbrake Switch. |
Brake Fluid Level Switch Test
- Ignition OFF, disconnect the harness connector at the B20 Brake Fluid Level Switch.
- Test for less than 10 Ω between the ground circuit terminal 2 and the signal circuit terminal 1.
⇒ | If less than the specified value, replace the B20 Brake Fluid Level Switch. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
© Copyright Chevrolet. All rights reserved |
© Copyright Chevrolet. All rights reserved |