Pinpoint Test P: DTC C1440 (Abs Only) - Pressure Transducer Signal Fault

WARNING: This page is about a different car, the 2005 Mercury Mountaineer and 2005 Ford Explorer. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Use the flex probe kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes.

P1 VERIFY THE DTC
- Connect the diagnostic tool.
- Key in ON position.
- Clear DTC C1440. Road test the vehicle. Repeat the self-test.
- Does DTC C1440 repeat?
- Yes : GO to P2.
- No : The system is OK at this time.
P2 MONITOR THE BRAKE PRESSURE SWITCH PID FOR A CLOSED POSITION
- Enter the following diagnostic mode on the diagnostic tool: Anti-lock Brake System (ABS) Module PID.
- Monitor the ABS module brake pressure switch PID.
- With the brake pedal released, does the PID read closed?
- Yes : GO to P3.
- No : GO to P4.
P3 MONITOR THE BRAKE PRESSURE SWITCH PID FOR AN OPEN POSITION
- Enter the following diagnostic mode on the diagnostic tool: ABS Module PID.
- Monitor the ABS module brake pressure switch PID.
- While pressing the brake pedal, does the PID read open?
- Yes : GO to P9.
- No : GO to P7.
P4 CHECK THE CIRCUIT 10 (LG) FOR AN OPEN
- Key in OFF position.
- Disconnect: Brake Pressure Switch C1025.
- Key in ON position.
- Measure the voltage between the brake pressure switch C1025-2, circuit 10 (LG), harness side and ground.
  
  Fig 1: Checking Circuit 10 (LG) For Open
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to P5.
- No : REPAIR the circuit. CLEAR the DTCs and REPEAT the self-test.
P5 CHECK THE BRAKE PRESSURE SWITCH
- Key in OFF position.
- Measure the resistance across the brake pressure switch pins, component side.
  
  Fig 2: Checking Brake Pressure Switch
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to P6.
- No : INSTALL a new brake pressure switch. REFER to SPEED CONTROL . CLEAR the DTCs and REPEAT the self-test.
P6 CHECK CIRCUIT 307 (BK/YE) FOR AN OPEN
- Connect: Brake Pressure Switch C1025.
- Disconnect: ABS Module C155.
- Measure the voltage between the ABS module C155-40, circuit 307 (BK/YE), harness side and ground.
  
  Fig 3: Measuring Voltage Between ABS Module And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to P9.
- No : REPAIR the circuit. CLEAR the DTCs and REPEAT the self-test.
P7 CHECK CIRCUIT 307 (BK/YE) FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: Brake Pressure Switch C1025.
- Key in ON position.
- Measure the voltage between the ABS module C155-40, circuit 307 (BK/YE), harness side and ground.
  
  Fig 4: Measuring Voltage Between ABS Module And Ground
  Courtesy of FORD MOTOR CO.
- Is any voltage present?
- Yes : REPAIR the circuit. CLEAR the DTCs and REPEAT the self-test.
- No : GO to P8.
P8 CHECK THE BRAKE PRESSURE SWITCH
- Start the engine.
- Measure the resistance between the brake pressure switch C1025-1, component side and the brake pressure switch C1025-2, component side while firmly pressing the brake pedal.
  
  Fig 5: Checking Brake Pressure Switch
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
- Yes : GO to P9.
- No : INSTALL a new brake pressure switch. REFER to SPEED CONTROL . CLEAR the DTCs and REPEAT the self-test.
P9 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect all the ABS connectors.
- Check for:
  - Corrosion
  - pushed-out pins
- Connect all the ABS 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 ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE . 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-test.