Pinpoint Test I: The Brake Warning Indicator Is Never/Always On

WARNING: This page is about a different car, the 2006 Mercury Grand Marquis and 2006 Ford Crown Victoria. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Use the correct probe adaptor(s) when making measurements. Failure to use the correct probe adaptor(s) may damage the connector.

I1 CARRY OUT THE INSTRUMENT CLUSTER INDICATOR LAMP CONTROL ACTIVE COMMAND USING THE DIAGNOSTIC TOOL
- Key in ON position.
- Enter the following diagnostic mode on the scan tool: Instrument Cluster Active Command.
- Select the instrument cluster indicator lamp control active command. Trigger the BRAKE warning indicator active command on and off. Observe the BRAKE warning indicator.
- Does the BRAKE warning indicator illuminate when triggered on, and turn off when triggered off?
Yes : GO to I2.

No : GO to I16.
I2 DETERMINE IF THE BRAKE WARNING INDICATOR IS ALWAYS ON
- Key in ON position.
- Observe the BRAKE warning indicator.
- Is the BRAKE warning indicator always on?
Yes : GO to I3.

No : GO to I8.
I3 CHECK CIRCUIT 977 (VT/WH) FOR A SHORT TO GROUND
- Key in OFF position.
- Disconnect: Instrument Cluster C2220.
- Measure the resistance between the instrument cluster C2220-8, circuit 977 (VT/WH), harness side and ground.
  
  Fig 1: Measuring Resistance Between Instrument Cluster C2220-8, Circuit 977 (VT/WH), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : GO to I4.

No : GO to I5.
I4 MONITOR THE ABS MODULE PIDs
- Key in ON position.
- Enter the following diagnostic mode on the scan tool: ABS Module PIDs.
- Select the ABS module PIDs. Monitor the fault PID for missing message source identifier.
- Does the PID show that the missing message is active?
Yes : GO to I16.

No : GO to I15.
I5 CHECK THE PARKING BRAKE SWITCH
- Disconnect: Parking Brake Switch C2015.
- Measure the resistance between the instrument cluster C2220-8, circuit 977 (VT/WH), harness side and ground.
  
  Fig 2: Measuring Resistance Between Instrument Cluster C2220-8, Circuit 977 (VT/WH), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : INSTALL a new parking brake switch. TEST the system for normal operation.

No : GO to I6.
I6 CHECK THE INPUT FROM THE BRAKE FLUID LEVEL SWITCH
- Disconnect: Brake Fluid Level Switch C124.
- Measure the resistance between the instrument cluster C2220-8, circuit 977 (VT/WH), harness side and ground.
  
  Fig 3: Measuring Resistance Between Instrument Cluster C2220-8, Circuit 977 (VT/WH), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : GO to I7.

No : REPAIR circuit 977 (VT/WH). TEST the system for normal operation.
I7 CHECK CIRCUIT 409 (TN/BK) FOR A SHORT TO GROUND
- Measure the resistance between the brake fluid level switch C124-2, circuit 409 (TN/BK), harness side and ground.
  
  Fig 4: Measuring Resistance Between Brake Fluid Level Switch C124 Pin 2, Circuit 409 (TN/BK), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : INSTALL a new brake fluid level switch. REFER to HYDRAULIC BRAKE ACTUATION . TEST the system for normal operation.

No : REPAIR the circuit. TEST the system for normal operation.
I8 CHECK THE PARKING BRAKE SWITCH INPUT
- Apply the parking brake.
- Does the BRAKE warning indicator illuminate?
Yes : GO to I9.

No : GO to I10.
I9 CHECK THE BRAKE FLUID LEVEL SWITCH CIRCUIT 57 (BK) FOR AN OPEN
- Key in OFF position.
- Disconnect: Brake Fluid Level Switch C124.
- Measure the resistance between the brake fluid level switch C124-1, circuit 57 (BK), harness side and ground.
  
  Fig 5: Measuring Resistance Between Brake Fluid Level Switch C124 Pin 1, Circuit 57 (BK), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : INSTALL a new brake fluid level switch. REFER to HYDRAULIC BRAKE ACTUATION . TEST the system for normal operation.

No : REPAIR the circuit. TEST the system for normal operation.
I10 CHECK THE PARKING BRAKE SWITCH CIRCUIT 57 (BK) FOR AN OPEN
- Key in OFF position.
- Disconnect: Parking Brake Switch C2015.
- Measure the resistance between the parking brake switch C2015-2, circuit 57 (BK), harness side and ground.
  
  Fig 6: Measuring Resistance Between Parking Brake Switch C306-2 And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to I11.

No : REPAIR the circuit. TEST the system for normal operation.
I11 BYPASS THE PARKING BRAKE SWITCH
- Connect a fused (5A) jumper wire between the parking brake switch C2015-1, circuit 409 (TN/BK), harness side and the parking brake switch J2015-2, circuit 57 (BK), harness side.
  
  Fig 7: Bypassing The Parking Brake Switch
  Courtesy of FORD MOTOR CO.
- Key in ON position.
- Does the BRAKE warning indicator illuminate?
Yes : INSTALL a new parking brake switch. TEST the system for normal operation.

No : REMOVE the jumper. GO to I12.
I12 CHECK CIRCUIT 409 (TN/BK) FOR AN OPEN TO THE PARKING BRAKE SWITCH
- Key in OFF position.
- Disconnect: Brake Fluid Level Switch C124.
- Disconnect: Parking Brake Switch C2015.
- Measure the resistance between the brake fluid level switch C124-2, circuit 409 (TN/BK), harness side and the parking brake switch circuit 409 (TN/BK), through the brake fluid level switch C124-1, circuit 409 (TN/BK), harness side.
  
  Fig 8: Checking Circuit 409 (TN/BK) For An Open To The Parking Brake Switch
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to I13.

No : REPAIR the circuit. TEST the system for normal operation.
I13 BYPASS THE BRAKE FLUID LEVEL SWITCH
- Disconnect: Brake Fluid Level Switch C124.
- Disconnect: Parking Brake Switch C2015.
- Key in ON position.
- Connect a fused (5A) jumper wire between the brake fluid level switch C124-3, circuit 977 (VT/WH), harness side and the brake fluid level switch C124-1, circuit 57 (BK), harness side.
  
  Fig 9: Bypassing The Brake Fluid Level Switch
  Courtesy of FORD MOTOR CO.
- Does the BRAKE warning indicator illuminate?
Yes : INSTALL a new brake fluid level switch. REFER to VEHICLE DYNAMIC SYSTEMS . TEST the system for normal operation.

No : REMOVE the jumper wire. GO to I14.
I14 CHECK CIRCUIT 977 (VT/WH) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the instrument cluster C2220-8, circuit 977 (VT/WH), harness side and the brake fluid level switch C124-1, circuit 977 (VT/WH) harness side.
  
  Fig 10: Measuring Resistance Between Instrument Cluster C2220-8 And Brake Fluid Level Switch C124-1
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to I16.

No : REPAIR the circuit. TEST the system for normal operation.
I15 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect the ABS module connector.
- Check for:
  - corrosion
  - pushed-out pins
- Connect the ABS module 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 ABS module. REFER to VEHICLE DYNAMIC 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.
I16 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION
- Disconnect the instrument cluster connector.
- Check for:
  - corrosion
  - pushed-out pins
- Connect the instrument cluster 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 instrument cluster. REFER to INSTRUMENT CLUSTER . 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.