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Home >> Lincoln >> 2021 >> Navigator Base, RWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 590 (EPAS Guided Routine) >> Pinpoint Tests >> Pinpoint Tests AJ: DTC U0131:XX Lost Communication With The PSCM And The PSCM Cannot Communicate With The Diagnostic Scan Tool >> PSCM Circuit Information
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PSCM Circuit Information

WARNING: This page is about a different car, the 2019 Ford Fusion. However, it is still accessible from the selected car via links, so may be relevant.

Refer to Power Steering Controls , for schematic and connector information.

Refer to Steering GSB for additional connector and wiring inspection tips.

NOTE: Use the correct probe adapters when making measurements. Failure to use the correct probe adapters may cause damage to the connector.
Fig 1: PSCM-A Connector - C1463A
G13316166Courtesy of FORD MOTOR CO.

Harness Side

Circuit Pin
B+ (Battery Positive Voltage) - SBF06 2 (GREEN/RED)
GND (Ground) - GD192 1 (BLACK/VIOLET)
Fig 2: PSCM-B Connector - C1463B
G13316167Courtesy of FORD MOTOR CO.

Harness Side

Circuit Pin
HS-CAN2- (High Speed Controller Area Network 2 Low) - VDB26 3 (GRAY/BLUE)
HS-CAN2+ (High Speed Controller Area Network 2 High) - VDB25 2 (GREEN/ORANGE)
Fig 3: High-Current Battery Junction Box Connector - C1716B
G13316168Courtesy of FORD MOTOR CO.

Harness Side

Circuit Pin
Fig 4: Gateway Module A (GWM) Connector - C2431
G13316169Courtesy of FORD MOTOR CO.

Harness Side

Circuit Pin
HS-CAN2- (High Speed Controller Area Network 2 Low) - VDB26 17 (GRAY)
HS-CAN2+ (High Speed Controller Area Network 2 High) - VDB25 18 (GREEN)
HS-CAN1- (High Speed Controller Area Network 1 Low) - VDB05 19 (WHITE)
HS-CAN1+ (High Speed Controller Area Network 1 High) - VDB04 20 (BLUE)
  1. AJ1: CHECK THE PSCM COMMUNICATION WITH THE DIAGNOSTIC SCAN TOOL 
    • Start the vehicle.
      • Make sure the engine ready indicator is illuminated for hybrid vehicles.
    • Retrieve the continuous memory DTCs.
    • Does the diagnostic scan tool communicate with the PSCM? 
    Yes No
    Go to  AJ2. Go to  AJ3.
  2. AJ2: CHECK THE MODULE DTCS 
    • Review the DTCs retrieved in the previous step.
    • Is DTC U0131: XX present in any module? 
    Yes No
    Go to  AJ3. If DTC U0131:XX is not present in any module, DISCONTINUE this test.
  3. AJ3: CHECK THE VEHICLE BATTERY AND CHARGING SYSTEM VOLTAGE 
    • Ignition ON, engine OFF.
    • Refer to Charging System - General Information and carry out Pinpoint Test A: Battery Condition Test (battery state of charge).
    • Does the battery pass the condition test (battery state of charge)? 
    Yes No
    Go to  AJ4. If DTC U0131:XX is not present in any module, DISCONTINUE this test.
  4. AJ4: CHECK THE PSCM BATTERY AND IGNITION VOLTAGE 
    • Ignition OFF.
    • PSCM_A connector disconnected. (C1463A)
    • PSCM_B connector disconnected. (C1463B)
    • Measure the voltage between:
      (+) PSCM_A (C1463A) Connector, Harness Side (-)
      B+ - SBF06 (GREEN/RED) - Pin 2 Ground
      IGN START/RUN Ground
    • Measure the voltage between:
      (+) PSCM_B (C1463B) Connector, Harness Side (-)
      B+ Ground
    • Measure the voltage between:
      (+) PSCM_A (C1463A) Connector, Harness Side (-)
      IGN START/RUN Ground
    • Measure the voltage between:
      (+) PSCM_C Connector, Harness Side (-)
      B+ Ground
    • Are the voltages greater than 11 volts? 
    Yes No
    Go to  AJ5. VERIFY all BJB and high-current BJB fuses are OK. If the fuses are OK, REPAIR the circuit.
    If the fuses are not OK, REFER to the Power Steering Controls to identify the possible cause of the circuit short.
  5. AJ5: CHECK THE PSCM GROUND CIRCUIT FOR AN OPEN 
    • Ignition OFF.
    • Disconnect the battery negative cable. Refer to the Battery Disconnect General Procedure in Battery, Mounting and Cables .
    • Measure the resistance between:
      (+) PSCM_A (C1463A) Connector, Harness Side (-)
      GND - GD192 (BLACK/VIOLET) - Pin 1 Ground
    • Measure the resistance between:
      (+) PSCM_B (C1463B) Connector, Harness Side (-)
      GND Ground
    • Is the resistance less than 3 ohms? 
    Yes No
    Go to  AJ6. REPAIR the circuit.
  6. AJ6: CHECK THE PSCM HS-CAN CIRCUITS FOR AN OPEN 
    • GWM connector disconnected. (C2431)
    • Measure the resistance between:
      (+) PSCM_A (C1463A) Connector, Harness Side (-) GWM (C2431) Connector, Harness Side
      HS-CAN2 HS-CAN2- - VDB26 - Pin 17
      HS-CAN2+ HS-CAN2+ - VDB25 - Pin 18
    • Measure the resistance between:
      (+) PSCM_B (C1463B) Connector, Harness Side (-) GWM (C2431) Connector, Harness Side
      HS-CAN2- - VDB26 (GRAY/BLUE) - Pin 3 HS-CAN2- - VDB26 - Pin 17
      HS-CAN2+ - VDB25 (GREEN/ORANGE) - Pin 2 HS-CAN2+ - VDB25 - Pin 18
    • Measure the resistance between:
      (+) PSCM_A (C1463A) Connector, Harness Side (-) GWM (C2431) Connector, Harness Side
      HS-CAN1 HS-CAN1- - VDB05 - Pin 19
      HS-CAN1 + HS-CAN1+ - VDB04 - Pin 20
    • Measure the resistance between:
      (+) PSCM_B (C1463B) Connector, Harness Side (-) GWM (C2431) Connector, Harness Side
      HS-CAN1 HS-CAN1- - VDB05 - Pin 19
      HS-CAN1 + HS-CAN1+ - VDB04 - Pin 20
    • Are the resistances less than 3 ohms? 
    Yes No
    Go to  AJ7. REPAIR the circuit.
  7. AJ7: VERIFY ALL PSCM WIRING CONNECTIONS 
    • Ignition OFF.
    • Disconnect all PSCM wire harness in-line electrical connectors. Refer to Power Steering Controls for connector information.
      • Refer to the PSCM Connection GSB for additional electrical connection checks.
    • Using a good light source, inspect all PSCM and related in-line electrical connector for:
      • corrosion - install a new connector or terminal and clear the module pins.
      • damaged or bent pins - install new terminals or pins.
      • pushed-out pins - install new pins or connectors.
      • spread terminals - install new terminals or connectors.
    • PSCM_A connector connected. (C1463A) Make sure the connector seats and latches correctly.
    • PSCM_B connector connected. (C1463B) Make sure the connector seats and latches correctly.
    • GWM connector connected. (C2431) Make sure all electrical connectors seat and latch correctly.
    • Connect all PSCM wire harness in-line electrical connectors. Make sure the connectors seat and latch correctly.
    • Connect the battery negative cable. Refer to Battery, Mounting and Cables .
    • Ignition ON, engine OFF.
    • Using a diagnostic scan tool, clear the U0131:XX DTC from the reporting module.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Start the vehicle.
      • Make sure the engine ready indicator is illuminated for hybrid vehicles.
    • Operate the system.
    • Read DTCs from all modules.
    • Is DTC U0131: XX present in any module? 
    Yes No
    Go to  AJ8. The system is operating correctly at this time. The concern may have been caused by a loose or corroded PSCM electrical connector or a wire harness in-line electrical connector and was repaired during this pinpoint test.
  8. AJ8: CHECK FOR CORRECT PSCM POWER AND GROUND JOINT OPERATION 
    • Ignition OFF.
    • Disconnect and inspect the PSCM ground joint connection, clean or repair as necessary. Refer to Power Steering Controls for ground joint information.
    • High-current Battery Junction Box connector disconnected. (C1716B)
    • Inspect the high-current BJB connection, clean or repair as necessary.
    • Connect the PSCM ground joint connection. Make sure the connection is clean, tight and not cross-threaded.
    • High-current Battery Junction Box connector connected. (C1716B) Make sure the connector seats and latches correctly.
    • Ignition ON, engine OFF.
    • Using a diagnostic scan tool, clear the U0131:XX DTC from the reporting module.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Start the vehicle.
      • Make sure the engine ready indicator is illuminated for hybrid vehicles.
    • Operate the system.
    • Retrieve the continuous memory DTCs.
    • Is DTC U0131: XX present in any module? 
    Yes No
    The concern may be an intermittent condition with the PSCM wiring harness which cannot be detected by voltage or resistance checks. Go to  AJ9. The system is operating correctly at this time. The concern may have been caused by a loose or corroded PSCM electrical connector or a wiring harness in-line electrical connector and was repaired during this procedure.
  9. AJ9: CHECK FOR INTERMITTENT PSCM WIRING HARNESS POWER AND GROUND CIRCUIT OPERATION 
    • Start the vehicle.
      • Make sure the engine ready indicator is illuminated for hybrid vehicles.
    • Make sure the front wheels are on the ground and the vehicle is not being supported by other means.
      • Make sure the front tires are clean and dry.
      • Make sure the ground under the front tires is clean and dry.
    • Take the following measurement while turning the steering wheel back and forth, lock to lock, continuously at 1 revolution per second.
    • Measure the voltage between:
      (+) 12 Volt Vehicle Battery (-) 12 Volt Vehicle Battery
      Positive terminal Negative terminal
    • Record the measured battery voltage.
    • View the following PID while turning the steering wheel back and forth, lock to lock, continuously at 1 revolution per second.
    • Access the PSCM and monitor the MOD_SUP_V (VOLT) PID.
    • Compare the measured battery voltage with the PID display.
      NOTE: If the scan tool cannot display the PID reading due to no communication with the PSCM, select the No Result/Action.
    • Does the measured battery voltage and the PID display differ by more than 1.5 volts? 
    Yes No
    INSTALL a new PSCM wiring harness.
    Go to  AJ10.    		 The system is operating correctly at this time. The concern may have been caused by a loose or corroded PSCM electrical connector or a wiring harness in-line electrical connector and was repaired during this procedure.
  10. AJ10: VERIFY PSCM OPERATION 
    • Start the vehicle.
      • Make sure the engine ready indicator is illuminated for hybrid vehicles.
    • Make sure the front wheels are on the ground and the vehicle is not being supported by other means.
      • Make sure the front tires are clean and dry.
      • Make sure the ground under the front tires is clean and dry.
    • Take the following measurement while turning the steering wheel back and forth, lock to lock, continuously at 1 revolution per second.
    • Measure the voltage between:
      (+) 12 Volt Vehicle Battery (-) 12 Volt Vehicle Battery
      Positive terminal Negative terminal
    • Record the measured battery voltage.
    • View the following PID while turning the steering wheel back and forth, lock to lock, continuously at 1 revolution per second.
    • Access the PSCM and monitor the MOD_SUP_V (VOLT) PID.
    • Compare the measured battery voltage with the PID display.
    • Does the measured battery voltage and the PID display differ by more than 1.5 volts? 
    Yes No
    INSTALL a new PSCM wiring harness.
    Go to  AJ11.    		 The repair is complete.
  11. AJ11: RETRIEVE DTCS FROM ALL MODULES 
    • Using a diagnostic scan tool, clear the U0131:XX DTC from the reporting module.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Start the vehicle.
      • Make sure the engine ready indicator is illuminated for hybrid vehicles.
    • Operate the system.
    • Retrieve the continuous memory DTCs.
    • Is DTC U0131: XX present in any module? 
    Yes No
    Go to  AJ12. The condition to set the DTC is not present and may have been caused by a loose, damaged or corroded electrical connector. The repair is complete, no further action is required.
  12. AJ12: CHECK FOR APPLICABLE SERVICE ARTICLES 
    • Ignition OFF.
    • Check OASIS for any applicable service messages; TSB, GSB, SSM or FSA.
    • Does a service article exist for DTC U0131 Lost Communication With The PSCM, PSCM no communication with the diagnostic scan tool or a lack of assist condition? 
    Yes No
    DISCONTINUE this test and FOLLOW the service article instructions. INSTALL a new EPAS gear. REFER to Power Steering article . ORDER a replacement EPAS gear and INCLUDE the RVC on the order form.
    If this is a Ford paid repair, INCLUDE the RVC on the warranty claim form.
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