Pinpoint Test J: The BRAKE Warning Indicator Is Always On
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test J: The BRAKE Warning Indicator Is Always On
Refer to Wiring Diagram Set 60, Instrument Cluster for schematic and connector information. Diagrams By Number
Normal Operation
When the parking brake is applied, the parking brake input circuit is grounded through the parking brake switch and the separate parking brake ground circuit. The parking brake applied ground is supplied to the Instrument Cluster (IC) through the brake fluid level switch and the brake warning indicator input circuit. The IC receives the ground signal and illuminates the BRAKE warning indicator.
When the brake fluid level is low, the brake warning indicator input circuit to the IC is grounded through the brake fluid level switch. The IC receives the ground signal and illuminates the BRAKE warning indicator.
When a base brake system concern occurs, the ABS module sends a signal to the IC over the communication network to illuminate the BRAKE warning indicator. If communication between the IC and the ABS module is lost, the IC turns on the BRAKE warning indicator.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Parking brake switch
- Brake fluid level switch (part of the brake fluid reservoir)
- ABS module
- IC
PINPOINT TEST J: THE BRAKE WARNING INDICATOR IS ALWAYS ON
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
NOTE: Verify that the parking brake is fully released and the brake fluid level is full before proceeding with this pinpoint test.
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J1 CARRY OUT THE IC INDICATOR LAMP ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger .
- Select the IC brake warning indicator (BRK_LAMP) active command on and off. Observe the BRAKE warning indicator.
- Does the BRAKE warning indicator illuminate when selected on and turn off when selected off?
Yes
GO to J2.
No
GO to J7.
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J2 CHECK THE PARKING BRAKE SWITCH INPUT
- Ignition OFF.
- Disconnect: Parking Brake Switch C2015 .
- Ignition ON.
- Monitor the BRAKE warning indicator.
- Does the BRAKE warning indicator turn off?
Yes
INSTALL a new parking brake switch. TEST the system for normal operation.
No
GO to J3.
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J3 CHECK THE BRAKE FLUID LEVEL SWITCH INPUT
NOTE: Verify that the brake fluid reservoir is full before proceeding with diagnosis of the brake fluid level switch.
- Ignition OFF.
- Disconnect: Brake Fluid Level Switch C124 .
- Ignition ON.
- Monitor the BRAKE warning indicator.
- Does the BRAKE warning indicator turn off?
Yes
GO to J4.
No
GO to J5.
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J4 CHECK THE PARKING BRAKE INPUT CIRCUIT FOR A SHORT TO GROUND
- Measure the resistance between the brake fluid level switch C124-2, circuit 409 (TN/BK), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
INSTALL a new brake fluid reservoir. REFER to Hydraulic Brake Actuation Brake Fluid Reservoir. TEST the system for normal operation.
No
REPAIR the circuit. TEST the system for normal operation.
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J5 CHECK THE BRAKE WARNING INDICATOR INPUT CIRCUIT FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: IC C2220 .
- Measure the resistance between the IC C2220-8, circuit 977 (VT/WH), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to J6.
No
REPAIR the circuit. TEST the system for normal operation.
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J6 MONITOR THE IC ABS MODULE MESSAGE
- Connect: IC C2220 .
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC DataLogger .
- Monitor the IC ABS input (ABS_MSG) PID for a missing CAN message.
- Does the PID display Yes?
Yes
VERIFY that the scan tool can communicate with the ABS module.
If the scan tool cannot establish communication with the ABS module, REFER to Module Communications Network Testing and Inspection.
If the scan tool does communicate with the ABS module, GO to J7.
No
GO to J8.
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J7 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect the ABS module connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the ABS module 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 ABS module. REFER to Vehicle Dynamic Systems 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.
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J8 CHECK FOR CORRECT IC OPERATION
- Disconnect the IC connector.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the IC 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 IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). 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.
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