Pinpoint Test A: Red Brake Warning Indicator Always On

WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

A1 CHECK THE PARKING BRAKE SWITCH
NOTE: Prior to troubleshooting the vehicle for this concern, verify that the rubber bumper on the parking brake pedal arm contacts the parking brake switch when the pedal is in the fully released position.
- Key in ON position.
- Disconnect: Parking Brake Switch C2015.
- Does the red brake warning light go out?
- Yes : INSTALL a new parking brake switch. TEST the system for normal operation.
- No : GO to A2.
A2 CHECK CIRCUIT 162 (LG/RD) FOR A SHORT TO GROUND
- Key in OFF position.
- Disconnect: Instrument Cluster C220b.
- Disconnect: Park Brake Relay C1170.
- Disconnect: Powertrain Control Module (PCM) C1381a (Diesel only).
- Measure the resistance between the park brake switch C2015 pin 1, circuit 162 (LG/RD), harness side and ground.
  
  Fig 1: Measuring Resistance Between Park Brake Switch C2015 Pin 1, Circuit 162 (LG/RD), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
- Yes : GO to A3.
- No : REPAIR the circuit. TEST the system for normal operation.
A3 CHECK THE BRAKE FLUID LEVEL SWITCH
- Disconnect: Brake Fluid Level Switch C124.
- Connect a fused (5A) jumper wire between the brake fluid level switch C124 pin 2, circuit 512 (TN/LG) and the brake fluid level switch C124 pin 3, circuit 531 (DG/YE), harness side.
  
  Fig 2: Connecting Fused (5A) Jumper Wire Between Brake Fluid Level Switch C124 Pin 2, Circuit 512 (TN/LG) And Brake Fluid Level Switch C124 Pin 3, Circuit 531 (DG/YE), Harness Side
  Courtesy of FORD MOTOR CO.
- Does the red brake warning light go out?
- Yes : INSTALL a new brake master cylinder. TEST the system for normal operation.
- No : GO to A4.
A4 CHECK CIRCUIT 512 (TN/LG) FOR A SHORT TO GROUND
- Measure the resistance between the brake fluid level switch C124 pin 2, circuit 512 (TN/LG), harness side and ground.
  
  Fig 3: Measuring Resistance Between Brake Fluid Level Switch C124 Pin 2, Circuit 512 (TN/LG), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
- Yes : GO to A5.
- No : REPAIR the circuit. TEST the system for normal operation.
A5 CHECK CIRCUIT 531 (DG/YE) FOR A SHORT TO GROUND
- Measure the resistance between the brake fluid level switch C124 pin 3, circuit 531 (DG/YE), harness side and ground.
  
  Fig 4: Measuring Resistance Between Brake Fluid Level Switch C124 Pin 3, Circuit 531 (DG/YE), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
- Yes : GO to A6.
- No : REPAIR the circuit. TEST the system for normal operation.
A6 CHECK FOR CORRECT INSTRUMENT CLUSTER OPERATION
- Disconnect all the instrument cluster connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect all the 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 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. CLEAR the DTCs. TEST the system for normal operation.