Pinpoint Test L: The Brake Warning Indicator is Never On
Instrumentation, Message Center and Warning Chimes
Pinpoint Test L: The Brake Warning Indicator is Never On
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information Electrical Diagrams.
Normal Operation
The Instrument Panel Cluster (IPC) uses 3 basic inputs to control the brake warning indicator. The first 2 are the parking brake warning indicator switch and brake fluid level switch. The third is for the Electronic Brake Distribution (EBD), controlled by the ABS. The parking brake warning indicator switch and brake fluid level switch are hardwired to the IPC (Instrument Panel Cluster) through independent signal circuits. The EBD (Electronic Brake Distribution) message is sent from the ABS module over the High Speed Controller Area Network (HS-CAN) communication bus.
The IPC (Instrument Panel Cluster) provides a reference voltage to both the parking brake warning indicator switch and the brake fluid level switch. When the parking brake is applied, the parking brake warning indicator switch closes to ground, providing a ground to the IPC (Instrument Panel Cluster) and pulling the signal circuit low. When a low brake fluid level condition exists, the low brake fluid level switch closes to ground pulling the signal circuit low. The IPC (Instrument Panel Cluster) monitors the parking brake and the brake fluid level inputs and illuminates the brake warning indicator when the parking brake is applied or when the brake fluid level is low. When the ABS module detects a base brake system concern, other ABS-related or EBD (Electronic Brake Distribution) concerns, the ABS module sends a message to the IPC (Instrument Panel Cluster) to illuminate both the ABS warning indicator and the brake warning indicator.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Parking brake warning indicator switch
- Brake fluid level switch
- IPC (Instrument Panel Cluster)
PINPOINT TEST L : THE BRAKE WARNING INDICATOR IS NEVER ON
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
L1 CHECK THE OPERATION OF THE IPC (Instrument Panel Cluster)
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC (Instrument Panel Cluster) DataLogger.
- Select the IPC (Instrument Panel Cluster) brake warning indicator (PBA_LMP) active command. Command the brake warning indicator on while observing the brake warning indicator.
Does the brake warning indicator illuminate?
Yes
GO to L2.
No
INSTALL a new IPC (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) Service and Repair. TEST the system for normal operation.
L2 CHECK THE OPERATION OF THE BRAKE WARNING INDICATOR FROM THE PARKING BRAKE SWITCH
- Apply the parking brake while monitoring the brake warning indicator.
Does the brake warning indicator illuminate?
Yes
GO to L5.
No
GO to L3.
L3 CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH
- Ignition OFF.
- Disconnect: Parking Brake Warning Indicator Switch C306.
- Ignition ON.
- Connect a fused jumper wire between the parking brake warning indicator switch C306-1, circuit CMC25 (WH/VT), harness side and ground.
Does the brake warning indicator illuminate?
Yes
INSTALL a new parking brake warning indicator switch. TEST the system for normal operation.
No
GO to L4.
L4 CHECK THE PARKING BRAKE SIGNAL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: IPC (Instrument Panel Cluster) C220.
- Measure the resistance between the IPC (Instrument Panel Cluster) C220-11, circuit CMC25 (WH/VT), harness side and the parking brake warning indicator switch C306-1, circuit CMC25 (WH/VT), harness side.
Is the resistance less than 5 ohms?
Yes
GO to L8.
No
REPAIR circuit CMC25 (WH/VT) for an open. TEST the system for normal operation.
L5 CHECK THE BRAKE FLUID LEVEL INPUT TO THE IPC (Instrument Panel Cluster)
NOTE: If the fuse in the jumper wire fails, repair circuit CE908 (BU/BN) for a short to voltage.
- Ignition OFF.
- Disconnect: Brake Fluid Level Switch C124.
- Connect a fused jumper wire between the brake fluid level switch C124-2, circuit CE908 (BU/BN), harness side and ground.
- Ignition ON.
- Monitor the brake warning indicator.
Does the brake warning indicator turn on?
Yes
GO to L6.
No
GO to L7.
L6 CHECK THE BRAKE FLUID LEVEL INDICATOR SWITCH GROUND CIRCUIT
- Ignition OFF.
- Measure the resistance between the brake fluid level switch C124-1, circuit GD187 (BK/GN), harness side and ground.
Is the resistance less than 5 ohms?
Yes
INSTALL a new brake fluid level switch. TEST the system for normal operation.
No
REPAIR circuit GD187 (BK/GN) for an open. TEST the system for normal operation.
L7 CHECK BRAKE FLUID LEVEL SIGNAL CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the IPC (Instrument Panel Cluster) C220-16, circuit CE908 (BU/BN), harness side and the brake fluid level switch C124-2, circuit CE908 (BU/BN), harness side.
Is the resistance less than 5 ohms?
Yes
GO to L8.
No
REPAIR circuit CE908 (BU/BN) for an open. TEST the system for normal operation.
L8 CHECK FOR CORRECT IPC (Instrument Panel Cluster) OPERATION
- Disconnect the IPC (Instrument Panel Cluster) connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the IPC (Instrument Panel Cluster) connector and make sure it seats correctly.
- Operate the system and verify the concern is still present.
Is the concern still present?
Yes
INSTALL a new IPC (Instrument Panel Cluster). REFER to Instrument Panel Cluster (IPC) Service and Repair. TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.