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Home >> Lincoln >> 2019 >> MKZ Base, AWD >> Repair and Diagnosis >> External Pages >> Different car >> Section 2242 (EPAS Guided Routine) >> Pinpoint Tests >> Pinpoint Tests AX: PSCM DTC U0252 Lost Communication with RLCM-B >> PSCM Circuit Information

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: Gateway Module A (GWM) Connector - C2431
G13316196Courtesy 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)
Fig 2: PSCM-B Connector - C1463B
G13316197Courtesy 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)
  1. AX1: VERIFY PSCM DTC 
    • Ignition ON, engine OFF.
    • Clear the PSCM DTCs.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Ignition ON, engine running.

    Carry out the PSCM self-test.

    • Is DTC U0252 currently present and active in the PSCM? 
    Yes No
    Go to  AX2. If the PSCM does NOT list DTC U0252 Lost Communication With The RLCM-B, DISCONTINUE this test and REFER to the DTC Chart for diagnostic direction.
  2. AX2: INSPECT THE PSCM COMMUNICATION WIRING AND CONNECTORS 
    NOTE: The PSCM receives messages from other modules through 2 connectors: the PSCM - A (or B) 3-pin connector at the gear and the multi pin in-line connector in the engine compartment. The in-line connector receives messages from there other modules into the PSCM wiring harness. The PSCM wiring harness uses the VDB wiring to carry the messages from the in-line connector to the PSCM - A (or B) 3-pin connector. If any of the connector pins or VDB communication wires are loose or damaged, the PSCM cannot properly receive messages from other modules.
    • Ignition OFF.
    • Disconnect PSCM-A (or B) 3-pin and the in-line electrical connectors.
    • Inspect both connectors for:
      • pushed-out pins, loose pins, spread terminals, water ingress and corrosion.
      • missing or loose latches, broken or cracked connector housings.
      • VDB wiring for pinched or cut wiring under brackets, air cleaner boxes, battery trays, engine pulleys, etc.
    • Inspect the VDB wiring for pinched or cut wiring under brackets, air cleaner boxes, battery trays, engine pulleys, etc.
    • Inspect the VDB wiring harness anchors for coming loose from anchoring locations in the engine compartment.
    • Repair the connectors or wiring as necessary.
    • Connect PSCM-A (or B) 3-pin and the in-line electrical connectors.
      • Verify connectors are solidly latched and connected without water ingress gaps.
      • Verify wiring harness anchors are solidly pushed into retaining holes, etc.
    • Ignition ON, engine OFF.
    • Clear the PSCM DTCs.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Ignition ON, engine running.

    Carry out the PSCM self-test.

    • Is DTC U0252 present in the PSCM? 
    Yes No
    Go to  AX3. The concern is not present at this time and may have been set due to a loose or damaged electrical connector. The test is complete, no further action is required.
  3. AX3: CHECK THE HS-CAN CIRCUITS FOR AN OPEN 
    • Ignition OFF.
    • GWM connector disconnected. (C2431)
    • PSCM_B connector disconnected. (C1463B)
    • 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
    The HS-CAN circuits are OK, Go to  AX4. REPAIR the circuit.
  4. AX4: RECHECK FOR PSCM DTC U0252 
    • GWM connector connected. (C2431) Make sure all electrical connectors seat and latch correctly.
    • PSCM_B connector connected. (C1463B) Make sure the connector seats and latches correctly.
    • Ignition ON, engine OFF.
    • Clear the PSCM DTCs.
    • Ignition OFF.
    • Wait at least 90 seconds for the modules to completely shut off.
    • Ignition ON, engine running.

    Carry out the PSCM self-test.

    • Is DTC U0252 currently present and active in the PSCM? 
    Yes No
    The PSCM HS-CAN circuits are working correctly at this time.
    RETRIEVE and RECORD all RLCM-B DTCs. REFER to Exterior Lighting System and DIAGNOSE the RLCM-B.    		 If the PSCM no longer lists DTC U0252, the concern was repaired during this pinpoint test and the PSCM HS-CAN circuits are working correctly at this time.
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