Pinpoint Test S: DTC C2777 AND DTC C2778 - SENSOR CLUSTER BUS 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: Measure all pins of the sensor cluster and ABS module when removing connectors. Care should be taken when reinstalling these connectors.

S1 CHECK THE VOLTAGE TO THE SENSOR CLUSTER
- Key in OFF position.
- Disconnect: Sensor Cluster C3073.
- Key in ON position.
- Measure the voltage between sensor cluster C3073-3, circuit 7-CF67 (YE/RD), harness side and ground.
  
  Fig 1: Measuring Voltage Between Sensor Cluster C3073-3, Circuit 7-CF67 (YE/RD), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : INSTALL a new sensor cluster. REFER to YAW RATE SENSOR in this article . CLEAR the diagnostic trouble codes (DTCs). RECALIBRATE the system. REPEAT the self-test.
- No : GO to S2.
S2 CHECK THE STEERING WHEEL ROTATION SENSOR
- Disconnect: Steering Wheel Rotation Sensor C226.
- Measure the voltage between sensor cluster C3073-3, circuit 7-CF67 (YE/RD), harness side and ground.
  
  Fig 2: Measuring Voltage Between Sensor Cluster C3073-3, Circuit 7-CF67 (YE/RD), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : INSTALL a new steering wheel rotation sensor. REFER to STEERING WHEEL ROTATION SENSOR in this article . CLEAR the DTCs. RECALIBRATE the system. REPEAT the self-test.
- No : GO to S3.
S3 CHECK CIRCUIT 7-CF67 (YE/RD) FOR A SHORT TO GROUND
- Key in OFF position.
- Disconnect: ABS Module C155.
- Measure the resistance between sensor cluster C3073-3, circuit 7-CF67 (YE/RD), harness side and ground.
  
  Fig 3: Measuring Resistance Between Sensor Cluster C3073-3, Circuit 7-CF67 (YE/RD), Harness Side And Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
- Yes : GO to S4.
- No : REPAIR the circuit. CLEAR the DTCs. RECALIBRATE the system. REPEAT the self-test.
S4 CHECK CIRCUIT 7-CF67 (YE/RD) FOR AN OPEN FROM THE SENSOR CLUSTER
- Measure the resistance between steering wheel rotation sensor C226-1, 7-CC16A (YE/BK), harness side and ABS module C155-7, circuit 7-CC1 (YE/RD), harness side.
  
  Fig 4: Measuring Resistance Between Steering Wheel Rotation Sensor C226-1, 7-CC16A (YE/BK), Harness Side & ABS Module C155-7, Circuit 7-CC1 (YE/RD), Harness Side
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : GO to S5.
- No : REPAIR the circuit. CLEAR the DTCs. RECALIBRATE the system. REPEAT the self-test.
S5 CHECK THE CAN BUS CIRCUITS FOR A SHORT TO VOLTAGE
- Key in ON position.
- Measure the voltage between sensor cluster C3073-1, circuit 5-CF66 (BU/WH), harness side and ground; and between sensor cluster C3073-2, circuit 4-CF66 (GY/VT), harness side and ground.
  
  Fig 5: Measuring Voltage Between Sensor Cluster C3073-1, Circuit 5-CF66, Harness Side And Ground; & Between Sensor Cluster C3073-2, Circuit 4-CF66, Harness Side & Ground
  Courtesy of FORD MOTOR CO.
- Is any voltage present?
- Yes : REPAIR the circuit in question. CLEAR the DTC. RECALIBRATE the system. REPEAT the self-test.
- No : GO to S6.
S6 CHECK THE CAN BUS CIRCUITS FOR A SHORT TO GROUND
- Key in OFF position.
- Measure the resistance between sensor cluster C3073-1, circuit 5-CF66 (BU/WH), harness side and ground; and between sensor cluster C3073-2, circuit 4-CF66 (GY/VT), harness side and ground.
  
  Fig 6: Measuring Resistance Between Sensor Cluster C3073-1, Circuit 5-CF66, Harness Side & Ground; & Between Sensor Cluster C3073-2, Circuit 4-CF66, Harness Side & Ground
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
- Yes : GO to S7.
- No : REPAIR the circuit in question. CLEAR the DTC. RECALIBRATE the system. REPEAT the self-test.
S7 CHECK THE CAN BUS CIRCUITS FOR A SHORT TOGETHER
- Measure the resistance between the sensor cluster C3073-1, circuit 5-CF66 (BU/WH), harness side and sensor cluster C3073-2, circuit 4-CF66 (GY/VT), harness side.
  
  Fig 7: Measuring Resistance Between Sensor Cluster C3073-1, Circuit 5-CF66 (BU/WH), Harness Side And Sensor Cluster C3073-2, Circuit 4-CF66 (GY/VT), Harness Side
  Courtesy of FORD MOTOR CO.
- Is the resistance greater than 10,000 ohms?
- Yes : GO to S8.
- No : REPAIR circuit 4-CF66 (GY/VT) and circuit 5-CF66 (BU/WH). CLEAR the DTC. RECALIBRATE the system. REPEAT the self-test.
S8 CHECK THE CAN BUS CIRCUITS FOR AN OPEN
- Measure the resistance between sensor cluster C3073-1, circuit 5-CF66 (BU/WH), harness side and ABS module C155-25, circuit 5-CF66 (BU/WH), harness side; and between sensor cluster C3073-2, circuit 4-CF66 (GY/VT), harness side and ABS module C155-29, circuit 4-CF66 (GY/VT), harness side.
  
  Fig 8: Measuring Resistance Between Sensor Cluster Circuits And ABS Module Circuits
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : INSTALL a new yaw rate sensor. REFER to YAW RATE SENSOR in this article . CLEAR the DTCs. RECALIBRATE the system. TEST DRIVE the vehicle. REPEAT the self-test.
  If DTC C2777 or C2778 is retrieved, INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE in this article . CLEAR the DTC. RECONFIGURE the ABS module. RECALIBRATE the system. REPEAT the self-test.
- No : REPAIR the circuit in question. CLEAR the DTC. RECALIBRATE the system. REPEAT the self-test.