Pinpoint Test P: DTC C1440 - PRESSURE TRANSDUCER INPUT CIRCUIT FAILURE

WARNING: This page is about a different car, the 2005 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Excessive clearance between brake pad and rotor, leaks, or air in the hydraulic brake system can also set DTC C1440.

P1 CHECK FOR DTCs
- Key in ON position.
- Connect the diagnostic tool.
- Retrieve the DTCs.
- Is DTC C1483, C1287, B2734, B2736, B2737, B2738 or B2740 present?
- Yes : SERVICE these DTCs first. GO to the appropriate pinpoint test for each DTC received.
- No : GO to P2.
P2 CHECK FOR 5 VOLT REFERENCE VOLTAGE TO THE PRESSURE TRANSDUCER
- Key in OFF position.
- Disconnect: Pressure Transducer C147.
- Key in ON position.
- Measure the voltage between pressure transducer C147-1, circuit 9-CF64 (BN/YE), harness side and pressure transducer C147-3, circuit 7-CF64 (YE/BK), harness side.
  
  Fig 1: Measuring Voltage Between Pressure Transducer C147-1, Circuit 9-CF64 (BN/YE), Harness Side And Pressure Transducer C147-3, Circuit 7-CF64 (YE/BK), Harness Side
  Courtesy of FORD MOTOR CO.
- Is the voltage approximately 5 volts?
- Yes : GO to P6.
- No : GO to P3.
P3 CHECK CIRCUITS FOR A SHORT TO VOLTAGE
- Key in OFF position.
- Disconnect: ABS Module C155.
- Key in ON position.
- Measure the voltage between pressure transducer C147-3, circuit 7-CF64 (YE/BK), harness side and ground; and between pressure transducer C147-1, circuit 9-CF64 (BN/YE), harness side and ground; and between pressure transducer C147-2, circuit 8-CF64 (WH/BK), harness side and ground.
  
  Fig 2: Measuring Voltage Between Pressure Transducer Circuits, Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is any voltage present?
- Yes : REPAIR the circuit in question. CLEAR the DTC. REPEAT the self-test.
- No : GO to P4.
P4 CHECK CIRCUITS FOR A SHORT TO GROUND
- Key in OFF position.
- Measure the resistance between pressure transducer C147-3, circuit 7-CF64 (YE/BK), harness side and ground; between pressure transducer C147-1, circuit 9-CF64 (BN/YE), harness side and ground; and between pressure transducer C147-2, circuit 8-CF64 (WH/BK), harness side and ground.
  
  Fig 3: Measuring Resistance Between Pressure Transducer Circuits, Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
- Yes : GO to P5.
- No : REPAIR the circuit in question. CLEAR the DTC. REPEAT the self-test.

P5 CHECK CIRCUIT RESISTANCE

Measure the resistance between ABS module C155 and pressure transducer C147 pins.

ABS Module C155	Pressure Transducer C147	Circuit
Pin 18	Pin 3	7-CF64 (YE/BK)
Pin 20	Pin 2	8-CF64 (WH/BK)
Pin 19	Pin 1	9-CF64 (BN/YE)

Is the resistance less than 5 ohms?

Yes : GO to P6.
No : REPAIR the circuit in question. CLEAR the DTC. REPEAT the self-test.

P6 CHECK THE SIGNAL FROM THE PRESSURE TRANSDUCER
- Connect: Pressure Transducer C147.
- Disconnect: ABS Module C155-20, circuit 8-CF64 (WH/BK).
- Connect: ABS Module C155.
- Key in ON position.
- Measure the voltage between ABS C155-20, circuit 8-CF64 (WH/BK), harness side and ground while applying and releasing the brake pedal.
  
  Fig 4: Measuring Voltage Between ABS C155-20, Circuit 8-CF64 (WH/BK), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is any voltage present?
- Yes : INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE in this article .
- No : INSTALL a new pressure transducer. CLEAR the DTC. REPEAT the self-test.