Pinpoint Test M: The Brake Warning Indicator is Never On
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test M: 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
The Instrument Panel Cluster (IPC) uses 3 basic messaged inputs to control the brake warning indicator. The first two are the parking brake warning indicator switch and the brake fluid level switch. The third is for the Electronic Brake Distribution (EBD) function controlled by the ABS module. The parking brake warning indicator switch and the brake fluid level switch status are sent from the Body Control Module (BCM) over the High Speed Controller Area Network (HS-CAN). The EBD message is sent from the ABS module over the HS-CAN.
The parking brake warning indicator switch is hardwired to the BCM through a single signal circuit while using a separate ground to control the input. The brake fluid level switch is hardwired to the BCM through separate signal and return circuits while using a separate ground to control the input.
The BCM 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, pulling the parking brake signal circuit low. When a low brake fluid level condition exists, the brake fluid level switch closes to ground, pulling the signal and return circuits low. If the brake fluid level switch is disconnected, the BCM reference voltage sent to the brake fluid level switch is sent high and the BCM sets DTC B1048:01. When the BCM detects either the brake fluid level signal or the parking brake signal circuits low, or the brake fluid level signal and return circuit high, the BCM sends the IPC a brake warning indicator on request.
When the ABS module detects a base brake system concern or other ABS related concerns that affect the EBD function, the ABS module sends a brake warning indicator on request to the IPC to illuminate the brake warning indicator and the ABS warning indicator.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Brake fluid level switch
- Parking brake warning indicator switch
- BCM
- IPC
PINPOINT TEST M: 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, results in false resistance readings. Refer to Battery, Mounting and Cables Battery Disconnect.
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M1 RETRIEVE THE RECORDED DTCs FROM THE IPC SELF-TEST
- Check for recorded IPC DTCs from the self-test.
- Are any DTCs recorded?
Yes
REFER to DTC Charts. Instrumentation, Message Center and Warning Chimes
No
GO to M2.
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M2 DETERMINE IF THE BRAKE WARNING INDICATOR OPERATES WITH THE PARKING BRAKE
- Ignition ON.
- Apply the parking brake while monitoring the brake warning indicator.
- Does the brake warning indicator illuminate with the parking brake applied?
Yes
RELEASE the parking brake. GO to M8.
No
RELEASE the parking brake. GO to M3.
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M3 CARRY OUT THE IPC INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IPC DataLogger.
- Select the IPC brake warning indicator (PBA_LMP) active command. Command the brake warning indicator on and observe the brake warning indicator.
- Does the brake warning indicator illuminate when commanded on?
Yes
GO to M4.
No
INSTALL a new IPC. REFER to Instrument Panel Cluster (IPC) Instrument Panel Cluster (IPC). TEST the system for normal operation.
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M4 CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH PID
- Enter the following diagnostic mode on the scan tool: BCM DataLogger.
- Select the BCM parking brake (PARK_BRK_SW) PID. Monitor the parking brake PID while applying the parking brake.
- Does the PID agree with the parking brake position?
Yes
GO to M12.
No
GO to M5.
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M5 CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH
- Disconnect: Parking Brake Warning Indicator Switch C2015.
- Connect a fused jumper wire between the parking brake warning indicator switch C2015-2, circuit GD120 (BK/GN), harness side and the parking brake warning indicator switch C2015-1, circuit CMC25 (WH/VT), harness side.
- Does the brake warning indicator illuminate?
Yes
REMOVE the jumper wire. INSTALL a new parking brake warning indicator switch. TEST the system for normal operation.
No
REMOVE the jumper wire. GO to M6.
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M6 CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the parking brake warning indicator switch C2015-2, circuit GD120 (BK/GN), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to M7.
No
REPAIR circuit GD120 (BK/GN) for an open. TEST the system for normal operation.
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M7 CHECK THE PARKING BRAKE WARNING INDICATOR SIGNAL CIRCUIT FOR AN OPEN
- Disconnect: BCM C2280C.
- Measure the resistance between the BCM C2280C-7, circuit CMC25 (WH/VT), harness side and the parking brake warning indicator switch C2015-1, circuit CMC25 (WH/VT), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to M12.
No
REPAIR circuit CMC25 (WH/VT) for an open. TEST the system for normal operation.
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M8 CHECK THE BRAKE FLUID LEVEL SWITCH OPERATION
- Ignition OFF.
- Disconnect: Brake Fluid Level Switch C124.
- Ignition ON.
- Does the brake warning indicator illuminate?
Yes
GO to M10.
No
GO to M9.
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M9 CHECK THE BRAKE FLUID LEVEL SIGNAL AND RETURN CIRCUITS FOR A SHORT TOGETHER
- Ignition OFF.
- Disconnect: BCM C2280F.
- Measure the resistance between the brake fluid level switch C124-2, circuit CMC19 (GY/VT), harness side and the brake fluid level switch C124-3, circuit RMC19 (YE/GY), harness side.
- Is the resistance greater than 10,000 ohms?
Yes
GO to M12.
No
REPAIR the circuits. TEST the system for normal operation.
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M10 CHECK THE BRAKE FLUID LEVEL SWITCH GROUND CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the brake fluid level switch C124-1, circuit GD120 (BK/GN), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to M11.
No
REPAIR circuit GD120 (BK/GN) for an open. TEST the system for normal operation.
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M11 CHECK THE BRAKE FLUID LEVEL SWITCH
- Ignition ON.
- NOTICE: Do not spill brake fluid onto painted or plastic surfaces. If spilled, wipe up immediately before damage to the painted or plastic surface occurs.
- Remove the brake fluid from the reservoir to allow the brake fluid level switch to fall to the bottom of the reservoir.
- Measure the resistance between the brake fluid level switch pin 3, component side and the brake fluid level switch pin 1, component side.
- Is the resistance less than 5 ohms?
Yes
GO to M12.
No
INSTALL a new brake fluid level switch. TEST the system for normal operation.
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M12 CHECK FOR CORRECT BCM OPERATION
- Disconnect all the BCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new BCM. REFER to Multifunction Electronic Modules 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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