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 warning indicator switch grounds circuit CCB09 (GY/BU) to the Smart Junction Box (SJB). The SJB receives the ground signal and sends the Instrument Cluster (IC) a message over the communication network to illuminate the brake warning indicator. When the brake fluid level is low, the brake fluid level switch closes, the signal from the SJB on circuit CMC19 (GY/VT) is grounded on circuit GD121 (BK/YE). When the ABS module detects a base brake system concern or other ABS-related concerns that affect the Electronic Brake Distribution (EBD) function, the ABS module sends a message to the IC to illuminate both the ABS warning indicator and the brake warning indicator.
NOTE: When the ABS module detects an EBD fault, the ABS module sends a message to the IC. Whenever the IC receives an EBD message from the ABS module, the IC illuminates both the brake warning indicator and the ABS warning indicator simultaneously.
- DTC B2479 (Brake Park Switch Circuit Short to Ground) - an on-demand DTC that sets in the SJB if a short to ground is detected on the parking brake input, circuit CCB09 (GY/BU).
- DTC C1125 (Brake Fluid Level Sensor Input Circuit Failure) - an on-demand DTC that sets in the SJB if a short to ground is detected on the brake fluid level input, circuit CMC19 (GY/VT).
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Parking brake warning indicator switch
- Brake fluid level switch (part of the brake fluid reservoir)
- Base brake system
- SJB
- 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 diagnostics.
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J1 CHECK THE BASE BRAKE SYSTEM
- Operate the brakes and verify that the base braking system operates correctly.
- Does the base braking system operate correctly?
Yes
GO to J2.
No
REFER to Brakes and Traction Control. Testing and Inspection
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J2 CHECK THE ABS WARNING INDICATOR OPERATION
- Ignition ON.
- Monitor the ABS warning indicator and the brake warning indicator following prove-out.
- Do both the ABS and brake warning indicators illuminate after prove-out?
Yes
Go To Pinpoint Test K. Pinpoint Test K: The ABS Warning Indicator Is Never/Always On
No
GO to J3.
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J3 RETRIEVE THE RECORDED IC DTCs FROM THE SELF-TEST
- Ignition OFF.
- Check for recorded continuous memory IC DTCs.
- Is DTC U1901 recorded?
Yes
REFER to Information Bus to diagnosis no communication with the SJB.
No
GO to J4.
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J4 RETRIEVE THE RECORDED DTCs FROM THE SJB SELF-TEST
- Check for recorded SJB DTCs from the self-test.
- Are any SJB DTCs recorded?
Yes
For DTC B2479, GO to J6.
For DTC C1125, GO to J9.
For all other SJB DTCs, REFER to DTC Charts. [1][2]Diagnostic Trouble Code Descriptions
No
GO to J5.
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J5 CARRY OUT THE IC INDICATOR LAMP CONTROL 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. Command the brake warning indicator on then off. Observe the brake warning indicator.
- Does the brake warning indicator illuminate when commanded on and turn off when commanded off?
Yes
GO to J11.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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J6 CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH PID
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB DataLogger.
- Monitor the SJB parking brake warning indicator switch PID (PRK_BRK) while applying and releasing the parking brake.
- Does the PID agree with the parking brake position?
Yes
GO to J11.
No
GO to J7.
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J7 CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH
- Ignition OFF.
- Disconnect: Parking Brake Warning Indicator Switch C306.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB DataLogger.
- Monitor the SJB parking brake warning indicator switch PID (PRK_BRK).
- Does the PID indicate that the parking brake is off?
Yes
INSTALL a new parking brake warning indicator switch. CLEAR the DTCs. REPEAT the self-test.
No
GO to J8.
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J8 CHECK CIRCUIT CCB09 (GY/BU) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: SJB C2280c.
- Measure the resistance between the SJB C2280c-9, circuit CCB09 (GY/BU), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to J11.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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J9 CHECK THE BRAKE FLUID LEVEL SWITCH OPERATION
- Ignition OFF.
- Disconnect: Brake Fluid Level Switch C124.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: SJB Self-Test.
- Clear the SJB DTCs. Repeat the SJB self-test.
- Is DTC C1125 still present?
Yes
GO to J10.
No
INSTALL a new brake fluid reservoir. CLEAR the DTCs. REPEAT the self-test.
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J10 CHECK CIRCUIT CMC19 (GY/VT) FOR A SHORT TO GROUND
- Ignition OFF.
- Disconnect: SJB C2280a.
- Measure the resistance between the SJB C2280a-25, circuit CMC19 (GY/VT), harness side and ground.
- Is the resistance greater than 10,000 ohms?
Yes
GO to J11.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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J11 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the SJB connectors and make sure they seat correctly.
- Operate the system and verify that the concern is still present.
- Is the concern still present?
Yes
INSTALL a new SJB. REFER to Body Control Systems. 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. CLEAR the DTCs. REPEAT the self-test.
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