Pinpoint Test M: The Brake Warning Indicator is Never On
Instrumentation and Warning Chimes
Pinpoint Test M: The Brake Warning Indicator is Never On
Refer to Wiring Diagrams Set 60, Instrument Cluster for schematic and connector information. Electrical Diagrams
Normal Operation
The Instrument Cluster (IC) uses 3 basic inputs to control the brake warning indicator. The first 2 are the parking brake warning indicator switch and the brake fluid level switch. The third is for the Electronic Brake Distribution (EBD), controlled by the ABS. The parking brake warning indicator switch is hardwired through the brake fluid level switch and the brake warning input circuit to the IC (Instrument Cluster). The EBD (Electronic Brake Distribution) input is a message sent from the ABS module over the High Speed Controller Area Network (HS-CAN) communication bus.
The IC (Instrument Cluster) provides a reference voltage on the brake warning input circuit. When the parking brake is applied, the parking brake warning indicator switch closes, supplying ground through the brake fluid level switch on the brake warning input circuit, pulling the reference voltage low to the IC (Instrument Cluster). When a low brake fluid level condition exists, the brake fluid level switch closes to ground pulling the brake warning input circuit low to the IC (Instrument Cluster). The IC (Instrument Cluster) monitors the brake warning input circuit and when the voltage is pulled low, the IC (Instrument Cluster) turns on the brake warning indicator. 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 IC (Instrument 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 (part of the brake fluid reservoir cap)
- IC (Instrument Cluster)
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 will result if false resistance readings.
M1 CARRY OUT THE IC (Instrument Cluster) INDICATOR LAMP ACTIVE COMMAND USING THE SCAN TOOL
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: IC (Instrument Cluster) DataLogger.
- Select the IC (Instrument Cluster) 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 M2.
No
INSTALL a new IC (Instrument Cluster). REFER to Instrument Cluster (IC) . TEST the system for normal operation.
M2 CHECK THE PARKING BRAKE SWITCH INPUT
- Apply the parking brake.
Does the BRAKE warning indicator illuminate?
Yes
GO to M3.
No
GO to M4.
M3 CHECK THE BRAKE FLUID LEVEL SWITCH GROUND CIRCUIT FOR AN OPEN
NOTE: Verify that the brake fluid is low or was low at the time the concern was identified before continuing with this test step.
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Disconnect: Brake Fluid Level Switch C124.
- Measure the resistance between the brake fluid level switch C124-3, circuit 91-GC7 (BK/BU), harness side and ground.
Is the resistance less then 5 ohms?
Yes
INSTALL a new brake fluid level switch (brake fluid reservoir cap). TEST the system for normal operation.
No
REPAIR circuit 91-GC7 (BK/BU) for an open. TEST the system for normal operation.
M4 CHECK THE PARKING BRAKE SWITCH
- Ignition OFF.
- Disconnect: Parking Brake Warning Indicator Switch C306.
- Connect a fused jumper wire between the parking brake warning indicator switch C306-1, circuit 31S-GE44 (BK/RD), harness side and ground.
- Ignition ON.
- Monitor the brake warning indicator.
Does the brake warning indicator turn on?
Yes
INSTALL a new parking brake warning indicator switch. TEST the system for normal operation.
No
GO to M5.
M5 CHECK THE BRAKE WARNING INPUT CIRCUIT TO THE PARKING BRAKE WARNING INDICATOR SWITCH FOR AN OPEN
- Ignition OFF.
- Disconnect: Brake Fluid Level Switch C124.
- Measure the resistance between the parking brake warning indicator switch C306-1, circuit 31S-GE44 (BK/RD), harness side and the brake fluid level switch C124-1, circuit 31S-GE44 (BK/RD), harness side.
Is the resistance less than 5 ohms?
Yes
GO to M6.
No
REPAIR circuit 31S-GE44 (BK/RD) for an open. TEST the system for normal operation.
M6 CHECK THE BRAKE FLUID LEVEL SWITCH
- Measure the resistance between the brake fluid level switch, pin 1, component side and the brake fluid level switch, pin 2, component side.
Is the resistance less than 5 ohms?
Yes
GO to M7.
No
INSTALL a new brake fluid level switch (brake fluid level reservoir cap). TEST the system for normal operation.
M7 CHECK THE BRAKE WARNING INPUT CIRCUIT FOR AN OPEN BETWEEN THE IC (Instrument Cluster) AND THE BRAKE FLUID LEVEL SWITCH
- Disconnect: IC (Instrument Cluster) C220B.
- Measure the resistance between the IC (Instrument Cluster) C220B-7, circuit 31S-GC6 (BK/YE), harness side and the brake fluid level switch C124-2, circuit 31S-GC6 (BK/YE) harness side.
Is the resistance less than 5 ohms?
Yes
GO to M8.
No
REPAIR circuit 31S-GC6 (BK/YE) for an open. TEST the system for normal operation.
M8 CHECK FOR CORRECT IC (Instrument Cluster) OPERATION
- Disconnect the IC (Instrument Cluster) connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect the IC (Instrument Cluster) 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 IC (Instrument Cluster). REFER to 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.