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

WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. 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 DETERMINE THE CONDITION
- Key in ON position.
- Apply and release the parking brake while observing the brake warning indicator.
- Is the brake warning indicator always ON?
Yes : GO to I9.

No : GO to I2.
I2 CHECK THE BRAKE WARNING INDICATOR FOR CORRECT OPERATION
- Key in OFF position.
- Key in ON position.
- Observe the brake warning indicator. The brake warning indicator should illuminate for 3 seconds then turn off.
- Does the brake warning indicator prove out correctly?
Yes : GO to I3.

No : GO to I17.
I3 MONITOR THE PARKING BRAKE SWITCH PID
- Connect the scan tool.
- Enter the following diagnostic mode on the scan tool: SJB PID.
- Select the SJB parking brake input switch status and monitor the parking brake PID while applying and releasing the parking brake.
- Does the PID agree with the position of the parking brake?
Yes : GO to I6.

No : GO to I4.
I4 CHECK THE PARKING BRAKE SIGNAL CIRCUIT 162 (LG/RD)
- Key in OFF position.
- Disconnect: Parking Brake Switch C306.
- Connect a fused (10A) jumper wire between the parking brake switch C306-1, circuit 162 (LG/RD), harness side and ground.
  
  Fig 1: Checking Parking Brake Signal Circuit 162 (LG/RD)
  Courtesy of FORD MOTOR CO.
- Key in ON position.
- Does the brake warning lamp illuminate?
Yes : INSTALL a new parking brake switch. REFER to PARKING BRAKE & ACTUATION . TEST the system for normal operation.

No : REMOVE the jumper wire. GO to I5.
I5 CHECK CIRCUIT 162 (LG/RD) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the parking brake switch C306-1, circuit 162 (LG/RD), harness side and the SJB C2280d-13, circuit 162 (LG/RD), harness side.
  
  Fig 2: Checking Circuit 162 (LG/RD) For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to I17.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
I6 CHECK THE BRAKE FLUID LEVEL SWITCH
- Key in OFF position.
- Disconnect: Brake Fluid Level Switch C124.
- Connect a fused (10A) jumper wire between the brake fluid level switch C124-1, circuit 512 (TN/LG), harness side and the brake fluid level switch C124-2, circuit 128 (VT/YE), harness side.
  
  Fig 3: Checking Brake Fluid Level Switch
  Courtesy of FORD MOTOR CO.
- Key in ON position.
- Is the brake warning indicator illuminated?
Yes : INSTALL a new brake fluid level switch. REFER to HYDRAULIC BRAKE ACTUATION . TEST the system for normal operation.

No : Leave the jumper wire connected. GO to I7.
I7 CHECK THE BRAKE FLUID LEVEL SWITCH CIRCUIT
- Key in OFF position.
- Disconnect: ABS Module C155.
- Measure the resistance between the ABS module C155-9, circuit 512 (TN/LG), harness side and the ABS module C155-8, circuit 128 (VT/YE), harness side.
  
  Fig 4: Checking Brake Fluid Level Switch Circuit
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : GO to I15.

No : REMOVE the jumper wire. GO to I8.
I8 CHECK CIRCUIT 512 (TN/LG) FOR AN OPEN
- Measure the resistance between the ABS module C155-9, circuit 512 (TN/LG), harness side and the brake fluid level switch C124-1, circuit 512 (TN/LG), harness side.
  
  Fig 5: Checking Circuit 512 (TN/LG) For Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
Yes : REPAIR circuit 128 (VT/YE). CLEAR the DTCs. REPEAT the self-test.

No : REPAIR circuit 512 (TN/LG). CLEAR the DTCs. REPEAT the self-test.
I9 RETRIEVE THE SJB RECORDED DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND SELF-TESTS
- Check the recorded SJB DTCs from the continuous and on-demand self-tests.
- Is DTC C1769 recorded?
Yes : GO to I10.

No : GO to I12.
I10 CHECK THE PARKING BRAKE SWITCH FOR CORRECT OPERATION
- Disconnect: Parking Brake Switch C306.
- Observe the brake warning indicator.
- Is the brake warning indicator illuminated?
Yes GO to I11.

No : INSTALL a new parking brake switch. REFER to PARKING BRAKE & ACTUATION . TEST the system for normal operation.
I11 CHECK FOR CORRECT OPERATION OF THE SJB
- Disconnect: SJB C2280d.
- Observe the brake warning indicator.
- Is the brake warning indicator illuminated?
Yes : GO to I16.

No : REPAIR circuit 162 (LG/RD). CLEAR the DTCs. REPEAT the self-test.
I12 CHECK THE BRAKE FLUID LEVEL SWITCH FOR CORRECT OPERATION
- Key in OFF position.
- Disconnect: Brake Fluid Level Switch C124.
- Key in ON position.
- Observe the brake warning indicator.
- Is the brake warning indicator illuminated?
Yes : GO to I13.

No : INSTALL a new brake fluid level switch. REFER to HYDRAULIC BRAKE ACTUATION . TEST the system for normal operation.
I13 CHECK CIRCUIT 128 (VT/YE) FOR A SHORT TO GROUND
- Key in OFF position.
- Disconnect: ABS Module C155.
- Measure the resistance between the brake fluid level switch C124-2, circuit 128 (VT/YE), harness side and ground.
  
  Fig 6: Checking Circuit 128 (VT/YE) For Short To Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
Yes : GO to I14.

No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
I14 MONITOR THE BRAKE FLUID LEVEL SWITCH PID
- Connect: ABS Module C155.
- Connect: Brake Fluid Level Switch C124.
- Connect the scan tool.
- Key in ON position.
- Enter the following diagnostic mode on the scan tool: ABS Module PID.
- Select the brake fluid level switch status and monitor the brake fluid level switch PID.
- Does the PID indicate a low brake fluid level condition?
Yes : GO to I15.

No : GO to I17.
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 determine if 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. CLEAR the DTCs. REPEAT the self-tests.
I16 CHECK FOR CORRECT SJB OPERATION
- Disconnect all the SJB connectors.
- Check for:
  - corrosion
  - 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. REFER to MULTIFUNCTION ELECTRONIC MODULES . CLEAR the DTCs. REPEAT the self-tests.

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-tests.
I17 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 determine if the concern is still present.
- Is the concern still present?
Yes : INSTALL a new instrument cluster. REFER to INSTRUMENT CLUSTER in this article. 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-tests.