Pinpoint Test I: The Brake Warning Indicator Is Never On
Instrumentation, Message Center and Warning Chimes
Pinpoint Test I: The BRAKE Warning Indicator Is Never 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, circuit 409 (TN/BK) is grounded through the parking brake switch and circuit 57 (BK). The parking brake applied ground is supplied to the Instrument Cluster (IC) through the brake fluid level switch and circuit 977 (VT/WH). The IC receives the ground signal and illuminates the BRAKE warning indicator.
When the brake fluid level is low, circuit 977 (VT/WH) to the IC is grounded through the brake fluid level switch and circuit 57 (BK). 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)
- IC
PINPOINT TEST I: 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.
NOTE: Failure to disconnect the battery when instructed will result if false resistance readings. Refer to Battery.
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I1 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 I2.
No
GO to I9.
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I2 CHECK THE PARKING BRAKE SWITCH INPUT
- Apply the parking brake.
- Does the BRAKE warning indicator illuminate?
Yes
GO to I3.
No
GO to I4.
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I3 CHECK THE BRAKE FLUID LEVEL SWITCH CIRCUIT 57 (BK) FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: Brake Fluid Level Switch C124.
- Measure the resistance between the brake fluid level switch C124-1, circuit 57 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new brake fluid reservoir. TEST the system for normal operation.
No
REPAIR the circuit. TEST the system for normal operation.
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I4 CHECK THE PARKING BRAKE SWITCH CIRCUIT 57 (BK) FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: Parking Brake Switch C2015.
- Measure the resistance between the parking brake switch C2015-1, circuit 57 (BK), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to I5.
No
REPAIR the circuit. TEST the system for normal operation.
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I5 BYPASS THE PARKING BRAKE SWITCH
- Connect: Negative Battery Cable.
- Connect a fused jumper wire between the parking brake switch C2015-2, circuit 409 (TN/BK), harness side and the parking brake switch C2015-1, circuit 57 (BK), harness side.
- Ignition ON.
- Does the BRAKE warning indicator illuminate?
Yes
INSTALL a new parking brake switch. TEST the system for normal operation.
No
REMOVE the jumper wire. GO to I6.
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I6 CHECK CIRCUIT 409 (TN/BK) FOR AN OPEN
- Ignition OFF.
- Disconnect: Brake Fluid Level Switch C124.
- Measure the resistance between the parking brake switch C2015-2, circuit 409 (TN/BK), harness side and the brake fluid level switch C124-2, circuit 409 (TN/BK), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to I7.
No
REPAIR the circuit. TEST the system for normal operation.
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I7 CHECK THE BRAKE FLUID LEVEL SWITCH
- Measure the resistance between the brake fluid level switch, pin 2, component side and the brake fluid level switch, pin 3, component side.
- Is the resistance less than 5 ohms?
Yes
GO to I8.
No
INSTALL a new brake fluid reservoir. TEST the system for normal operation.
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I8 CHECK CIRCUIT 977 (VT/WH) FOR AN OPEN
- Disconnect: IC C2220.
- Measure the resistance between the IC C2220-8, circuit 977 (VT/WH), harness side and the brake fluid level switch C124-3, circuit 977 (VT/WH) harness side.
- Is the resistance less than 5 ohms?
Yes
GO to I9.
No
REPAIR the circuit. TEST the system for normal operation.
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I9 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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