Pinpoint Test G: DTC C1778 - Power Steering Failure

WARNING: This page is about a different car, the 2006 Mercury Mariner and 2006 Ford Escape. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Use the correct probe adapter(s) when taking measurements. Failure to use the correct probe adapter(s) may damage the connector.

NOTE: Repair DTC C2278 before proceeding with this pinpoint test.

G1 CHECK THE POWER STEERING CONTROL MODULE CIRCUIT 838 (LG/VT) FOR VOLTAGE
- Key in OFF position.
- Disconnect: Power Steering Control Module
- Measure the voltage between power steering control module C1463b. C1463b-1, circuit 838 (LG/VT), harness side and ground.
  
  Fig 1: Checking Power Steering Control Module Circuit 838 (LG/VT) For Voltage
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes: GO to G2.

No: INSPECT BJB fuses 25 (50A) and 32 (50A), if OK, REPAIR circuit 838 (LG/VT) for an open. CLEAR the DTCs. CYCLE the ignition switch to the OFF position for 3 seconds. REPEAT the self-test.
G2 CHECK THE POWER STEERING CONTROL MODULE CIRCUIT 601 (LB/PK) FOR VOLTAGE
- Disconnect: Power Steering Control Module C1463a.
- Key in ON position.
- Measure the voltage between power steering control module C1463a-1, circuit 601 (LB/PK), harness side and ground.
  
  Fig 2: Checking Power Steering Control Module Circuit 601 (LB/PK) For Voltage
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
Yes: GO to G3.

No: INSPECT SJB fuses 34 (5A), if OK, REPAIR circuit 601 (LB/PK) for an open. CLEAR the DTCs. CYCLE the ignition switch to the OFF position for 3 seconds. REPEAT the self-test.
G3 CHECK THE POWER STEERING CONTROL MODULE CIRCUIT 57 (BK) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between power steering control module C1463b-3, circuit 57 (BK), harness side and ground.
  
  Fig 3: Checking Power Steering Control Module Circuit 57 (BK) For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 2 ohms?
Yes: GO to G4.

No: REPAIR circuit 57 (BK) for an open. CLEAR the DTCs. CYCLE the ignition switch to the OFF position for 3 seconds. REPEAT the self-test.
G4 CHECK CIRCUITS 3140 (BK) AND 3141 (WH) FOR AN OPEN
- Key in OFF position.
- Disconnect: Power Steering Motor C1467a.
- Measure the resistance between power steering control module C1463b-2, circuit 3140 (BK), harness side and power steering motor C1467a-2, circuit 3140 (BK), harness side; and between power steering control module C1463b-4, circuit 3141 (WH), harness side and power steering motor C1467a-1, circuit 3141 (WH), harness side.
  
  Fig 4: Checking Circuits 3140 (BK) & 3141 (WH) For An Open
  Courtesy of FORD MOTOR CO.
- Are the resistances less than 2 ohms?
Yes: GO to G5.

No: REPAIR circuit(s) 3140 (BK) and/or 3141 (WH) for an open. CLEAR the DTCs. CYCLE the ignition switch to the OFF position for 3 seconds. REPEAT the self-test.
G5 CHECK THE STEERING GEAR MOTOR FOR AN OPEN
- Measure the resistance between power steering motor C1467a-2, circuit 3140 (BK), component side and power steering motor C1467a-1, circuit 3141 (WH), component side.
  
  Fig 5: Checking Steering Gear Motor For An Open
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 2 ohms?
Yes: GO to G6.

No: INSTALL a new steering gear. REFER to REMOVAL AND INSTALLATION . CLEAR the DTCs. CYCLE the ignition switch to the OFF position for 3 seconds. REPEAT the self-test.
G6 CHECK FOR CORRECT POWER STEERING CONTROL MODULE OPERATION
- Disconnect all the power steering control module connectors.
- Check for:
  - corrosion.
  - pushed-out pins.
- Connect all power steering control module connectors and make sure they are seated correctly.
- Operate the system and verify if the concern is still present.
- Is the concern still present?
Yes: INSTALL a new power steering control module. REFER to REMOVAL AND INSTALLATION . CLEAR the DTCs. CYCLE the ignition switch to the OFF position for 3 seconds. 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. CYCLE the ignition switch to the OFF position for 3 seconds. REPEAT the self-test.