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Home >> Ford >> 2005 >> Freestar Base >> Repair and Diagnosis >> Brakes >> Traction Control >> Anti-Lock Brake System >> Diagnosis And Testing >> Anti-Lock Control >> Pinpoint Tests >> Pinpoint Test G: DTCs C1277 and C1278 - Steering Wheel Angle 1 and 2 Circuit Failure/Faulted >> PINPOINT TEST G: DTCs C1277 AND C1278 - STEERING WHEEL ANGLE 1 AND 2 CIRCUIT FAILURE/FAULTED

PINPOINT TEST G: DTCs C1277 AND C1278 - STEERING WHEEL ANGLE 1 AND 2 CIRCUIT FAILURE/FAULTED

CAUTION: Over tightening of the steering wheel rotation sensor fasteners may deform or damage the sensor housing, possibly resulting in faulty operation.
NOTE: Make sure that the steering wheel rotation sensor is mounted securely to the column with two fasteners. A loose sensor or missing fastener may result in incorrect sensor operation. Examine the sensor/disk interface to make sure that the disk rotates freely within the slot of the sensor. Examine the disk for physical damage or blocked holes near the disk perimeter. Make sure that the sensor connector is mated securely to the harness connector. Before proceeding with electrical testing, make sure that the vehicle battery is fully charged.
  1. G1 CARRY OUT THE RECALIBRATION PROCEDURE 
    • Key in ON position.
    • Enter the following diagnostic mode on the diagnostic tool: Clear the DTCs.
    • Carry out the steering wheel rotation sensor recalibration procedure following the diagnostic tool directions.
    • Test drive the vehicle.
    • Enter the following diagnostic mode on the diagnostic tool: Retrieve DTCs.
    • Are any DTCs retrieved or does the recalibration procedure indicate a fault? 
  2. G2 MONITOR THE STEERING WHEEL ROTATION SENSOR PIDs 
    • Enter the following diagnostic mode on the diagnostic tool: ABS Module PIDs.
    • Monitor the ABS module steering wheel rotation sensor PIDs while rotating the steering wheel clockwise and counterclockwise very slowly.
    • Do the PIDs move in intervals of 4.5 degrees? 
    • YES  : CLEAR the DTCs. DRIVE the vehicle. RETRIEVE the DTCs. If DTC C1277 or C1278 is still present, GO to  G12.
    • NO  : GO to  G3.
  3. G3 CHECK CIRCUIT 640 (RD/YE) FOR VOLTAGE 
    • Key in OFF position.
    • Disconnect: Steering Wheel Rotation Sensor C226.
    • Key in ON position.
    • Measure the voltage between the steering wheel rotation sensor C226-1, circuit 640 (RD/YE), harness side and ground.
      Fig 1: Measuring Voltage Between Steering Wheel Rotation Sensor C226-1, Circuit 640 (RD/YE), Harness Side And Ground
      G04000665Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    • YES  : GO to  G4.
    • NO  : REPAIR the circuit. CLEAR the DTCs. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REPEAT the self-test.
  4. G4 CHECK THE STEERING WHEEL ROTATION SENSOR CIRCUITRY FOR AN OPEN 
    • Key in OFF position.
    • Disconnect: ABS Module C155.
    • Measure the resistance between the ABS module connector, harness side and the steering wheel rotation sensor connector, harness side as follows in CONNECTOR PINOUTS REFERENCE  table:
      CONNECTOR PINOUTS REFERENCE

      Steering Wheel Rotation Sensor Connector-Pin ABS Module Connector-Pin Circuit
      C226-2 C155-10 1573 (YE)
      C226-3 C155-39 1572 (DG)
      C226-4 C155-24 1571 (BK)
    • Are the resistances less than 5 ohms? 
    • YES  : GO to  G5.
    • NO  : REPAIR the circuit(s) in question. CLEAR the DTCs. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REPEAT the self-test.
  5. G5 CHECK THE STEERING WHEEL ROTATION SENSOR CIRCUITS FOR A SHORT TO VOLTAGE 
    • Key in ON position.
    • Measure the voltage between the ABS module connector, harness side and ground as follows in CONNECTOR PINOUTS REFERENCE  table:
      CONNECTOR PINOUTS REFERENCE

      ABS Module Connector-Pin Circuit
      C155-10 1573 (YE)
      C155-39 1572 (DG)
      C155-24 1571 (BK)
    • Is any voltage present? 
    • YES  : REPAIR the circuit(s) in question. CLEAR the DTCs. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REPEAT the self-test.
    • NO  : GO to  G6.
  6. G6 CHECK THE STEERING WHEEL ROTATION SENSOR CIRCUITRY FOR A SHORT TO GROUND 
    • Key in OFF position.
    • Measure the resistance between the ABS module connector, harness side and ground as follows in CONNECTOR PINOUTS REFERENCE  table:
      CONNECTOR PINOUTS REFERENCE

      ABS Module Connector-Pin Circuit
      C155-10 1573 (YE)
      C155-39 1572 (DG)
      C155-24 1571 (BK)
    • Are the resistances greater than 10,000 ohms? 
    • YES  : GO to  G7.
    • NO  : REPAIR the circuit in question. CLEAR the DTCs. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REPEAT the self-test.
  7. G7 CHECK FOR VOLTAGE TO THE STEERING WHEEL ROTATION SENSOR 
    • Connect: ABS Module C155.
    • Connect: Steering Wheel Rotation Sensor C226.
    • Key in ON position.
    • With the connector connected, backprobe the connector while measuring the voltage between the steering wheel rotation sensor C226-1, circuit 640 (RD/YE), harness side and the steering wheel rotation sensor C226-4, circuit 1571 (BK), harness side.
      Fig 2: Checking Voltage To Steering Wheel Rotation Sensor
      G04000666Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    • YES  : GO to  G9.
    • NO  : GO to  G8.
  8. G8 CHECK THE STEERING WHEEL ROTATION SENSOR FOR A SHORT TO GROUND 
    • Key in OFF position.
    • Disconnect: Steering Wheel Rotation Sensor C226.
    • Key in ON position.
    • Measure the voltage between the steering wheel rotation sensor C226-1, circuit 640 (RD/YE), harness side and the steering wheel rotation sensor C226-4, circuit 1571 (BK), harness side.
      Fig 3: Checking Steering Wheel Rotation Sensor For Short To Ground
      G04000667Courtesy of FORD MOTOR CO.
    • Is the voltage greater than 10 volts? 
    • YES  : INSTALL a new steering wheel rotation sensor. CLEAR the DTCs. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REPEAT the self-test.
    • NO  : GO to  G12.
  9. G9 CHECK THE STEERING WHEEL ROTATION SENSOR OUTPUT SIGNAL A 
    • Key in OFF position.
    • Connect: ABS Module C155.
    • Connect: Steering Wheel Rotation Sensor C226.
    • Key in ON position.
    • With the connector connected, backprobe the connector while measuring the voltage between the steering wheel rotation sensor C226-3, circuit 1572 (DG), harness side and the steering wheel rotation sensor C226-4, circuit 1571 (BK), harness side while rotating the steering wheel slightly.
      Fig 4: Checking Steering Wheel Rotation Sensor Output Signal A
      G04000668Courtesy of FORD MOTOR CO.
    • Is the voltage between 0.25 volts and 0.75 volts or between 4.00 volts and 4.75 volts with the steering wheel stationary and change to the other state when rotating the steering wheel slightly? 
    • YES  : GO to  G10.
    • NO  : GO to  G11.
  10. G10 CHECK THE STEERING WHEEL ROTATION SENSOR OUTPUT SIGNAL B 
    • With the connector connected, backprobe the connector while measuring the voltage between the steering wheel rotation sensor C226-2, circuit 1573 (YE), harness side and the steering wheel rotation sensor C226-4, circuit 1571 (BK), harness side while rotating the steering wheel slightly.
      Fig 5: Checking Steering Wheel Rotation Sensor Output Signal B
      G04000669Courtesy of FORD MOTOR CO.
    • Is the voltage between 0.25 volts and 0.75 volts or between 4.00 volts and 4.75 volts with the steering wheel stationary and change to the other state when rotating the steering wheel slightly? 
    • YES  : CLEAR the DTCs. DRIVE the vehicle. RETRIEVE the DTCs. If DTC C1277 or C1278 is still present, GO to  G12.
    • NO  : GO to  G11.
  11. G11 CHECK FOR STEERING WHEEL ROTATION SENSOR REFERENCE VOLTAGE 
    • Key in OFF position.
    • Disconnect: Steering Wheel Rotation Sensor C226.
    • Key in ON position.
    • Measure the voltage between the steering wheel rotation sensor C226-3, circuit 1572 (DG), harness side and the steering wheel rotation sensor C226-4, circuit 1571 (BK), harness side; and between the steering wheel rotation sensor C226-2, circuit 1573 (YE), harness side and the steering wheel rotation sensor C226-4, circuit 1571 (BK), harness side.
      Fig 6: Checking Steering Wheel Rotation Sensor Reference Voltage
      G04000670Courtesy of FORD MOTOR CO.
    • Are the voltages between 4.75 volts and 5.25 volts? 
    • YES  : INSTALL a new steering wheel rotation sensor. CLEAR the DTCs. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REPEAT the self-test.
    • NO  : GO to  G12.
  12. G12 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 ANTI-LOCK BRAKE SYSTEM (ABS) MODULE . RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REPEAT the self-test.
    • 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.
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