Pinpoint Test J: The Brake Warning Indicator Is Never On
Instrumentation, Message Center and Warning Chimes
Pinpoint Tests
Pinpoint Test J: The Brake Warning Indicator Is Never On
Refer to Wiring Diagram Set 60 (Escape/Mariner, Escape Hybrid/Mariner Hybrid), Instrument Cluster for schematic and connector information. Diagrams By Number
Normal Operation
The Instrument Cluster (IC) uses 3 basic messaged inputs to control the brake warning indicator. The first 2 are the parking brake warning indicator switch and brake fluid level switch. The third is for the Electronic Brake Distribution (EBD), controlled by the ABS module. The parking brake warning indicator switch status is sent from the Smart Junction Box (SJB) over the Medium Speed Controller Area Network (MS-CAN) communication bus. The brake fluid level switch status is sent from the SJB over the MS-CAN. The EBD message is sent from the ABS module over the High Speed Controller Area Network (HS-CAN) communication bus lines. The parking brake warning indicator switch is hardwired to the SJB through signal circuit CMC25 (WH/VT). The brake fluid level switch is hardwired to the SJB through signal circuit CMC19 (GY/VT).
The SJB provides a reference voltage to both the parking brake switch and the brake fluid level switch. When the parking brake is applied, the parking brake warning indicator switch closes to ground through circuit GD182 (BK/GY), providing a ground to the SJB and pulling signal circuit CMC25 (WH/VT) low. When a low brake fluid level condition exists, the low brake fluid level switch closes to ground through circuit GD120 (BK/GN), pulling signal circuit CMC19 (GY/VT) low. The SJB monitors the parking brake input and sends the IC a message to turn the brake warning indicator on when the parking brake is applied. The SJB monitors the brake fluid level and sends the IC a message to turn on the brake warning indicator when a low brake fluid level condition exists. 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 message to the IC 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
- Brake fluid level switch
- Parking brake warning indicator switch
- SJB
- ABS module
- IC
PINPOINT TEST J: 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 in false resistance readings. Refer to Battery.
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J1 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 and observe the brake warning indicator.
- Does the brake warning indicator illuminate when commanded on?
Yes
GO to J2.
No
INSTALL a new IC. REFER to Instrument Cluster (IC) Instrument Cluster (IC). TEST the system for normal operation.
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J2 CHECK THE PARKING BRAKE SWITCH PID
- Enter the following diagnostic mode on the scan tool: SJB DataLogger.
- Select the SJB parking brake (PRK_BRAKE) PID. Monitor the parking brake PID while applying the parking brake.
- Does the PID agree with the parking brake position?
Yes
GO to J6.
No
GO to J3.
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J3 CHECK THE PARKING BRAKE WARNING INDICATOR SWITCH
- Ignition OFF.
- Disconnect: Parking Brake Warning Indicator Switch C2015.
- Connect a fused jumper wire between the parking brake warning indicator switch C2015-1, circuit GD182 (BK/GY), harness side and the parking brake warning indicator switch C2015-2, circuit CMC25 (WH/VT), harness side.
- Ignition ON.
- Monitor the brake warning indicator.
- 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 J4.
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J4 CHECK CIRCUIT GD182 (BK/GY) FOR AN OPEN
- Ignition OFF.
- Disconnect: Negative Battery Cable.
- Measure the resistance between the parking brake switch C2015-1, circuit GD182 (BK/GY), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to J5.
No
REPAIR the circuit. TEST the system for normal operation.
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J5 CHECK CIRCUIT CMC25 (WH/VT) FOR AN OPEN
- Disconnect: SJB C2280c.
- Measure the resistance between the SJB C2280c-1, circuit CMC25 (WH/VT), harness side and the parking brake switch C2015-2, circuit CMC25 (WH/VT), harness side and ground.
- Is the resistance less than 5 ohms?
Yes
GO to J9.
No
REPAIR the circuit. TEST the system for normal operation.
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J6 CHECK THE BRAKE FLUID LEVEL SWITCH
NOTE: Verify that the brake fluid level is low or was low prior to either adding brake fluid or a brake system repair.
- Ignition OFF.
- Disconnect: Brake Fluid Level Switch C124.
- Connect a fused jumper wire between the brake fluid level switch C124-1, circuit GD120 (BK/GN), harness side and the brake fluid level switch C124-2, circuit CMC19 (GY/VT), harness side.
- Ignition ON.
- Monitor the brake warning indicator.
- Does the brake warning indicator turn on?
Yes
INSTALL a new brake fluid level switch. TEST the system for normal operation.
No
DISCONNECT the jumper wire. GO to J7.
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J7 CHECK CIRCUIT CMC19 (GY/VT) FOR AN OPEN
- Ignition OFF.
- Disconnect: SJB C2280f.
- Measure the resistance between the SJB C2280f-9, circuit CMC19 (GY/VT), harness side and the brake fluid level switch C124-2, circuit CMC19 (GY/VT), harness side; and between the SJB C2280f-22, circuit CMC19 (GY/VT), harness side and the brake fluid level switch C124-2, circuit CMC19 (GY/VT), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to J8.
No
REPAIR the circuit. TEST the system for normal operation.
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J8 CHECK CIRCUIT GD120 (BK/GN) FOR AN OPEN
- 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 J9.
No
REPAIR the circuit. TEST the system for normal operation.
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J9 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 determine if the concern is still present.
- Is the concern still present?
Yes
INSTALL a new SJB. CLEAR the DTCs. REPEAT the self-test.
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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