LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Audi >> 2009 >> A4 Base, 2D Convertible >> Repair and Diagnosis >> External Pages >> Different car >> Section 1247 (EPAS Guided Routine Testing) >> Pinpoint Tests >> Pinpoint Test AH: PSCM DTC U0100 Lost Communication With The ECM/PCM A >> PSCM Circuit Information
April 5, 2026: LEMON Manuals is launched! Read the announcement.

PSCM Circuit Information

WARNING: This page is about a different car, the 2018 Lincoln Navigator. 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.

CAUTION: 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 End View (C1463A)
G08267494Courtesy of FORD MOTOR CO.
Harness Side

Circuit Pin
Fig 2: PSCM-B Connector End View (C1463B)
G11676840Courtesy of FORD MOTOR CO.
Harness Side

Circuit Pin
CAN- (Controller Area Network) - VDB26 3 (GRAY/BLUE)
CAN+ (Controller Area Network) - VDB25 2 (GREEN/ORANGE)
Fig 3: Data Link Connector End View (C251)
G12751664Courtesy of FORD MOTOR CO.
Harness Side

Circuit Pin
CAN- (Controller Area Network) - VDB05 19 (WHITE)
CAN+ (Controller Area Network) - VDB04 20 (WHITE/BLUE)
  1. AH1: 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 U0100 currently present and active in the PSCM? 
      Yes No
      Go to  AH2. If the PSCM does NOT list DTC U0100 Lost Communication With The ECM/PCM, DISCONTINUE this test and REFER to the DTC Chart for diagnostic direction.
  2. AH2: 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 U0100 present in the PSCM? 
      Yes No
      Go to  AH3. 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. AH3: CHECK THE HS-CAN CIRCUITS FOR AN OPEN 
    • Ignition OFF.
    • DLC connector disconnected. (C251)
    • PSCM_A connector disconnected. (C1463A)
    • PSCM_B connector disconnected. (C1463B)
    • Measure the resistance between:
      (+) PSCM_A (C1463A) Connector, Harness Side (-) DLC (C251) Connector, Harness Side
      CAN- CAN- - VDB05 - Pin 19
      CAN+ CAN+ - VDB04 - Pin 20
    • Measure the resistance between:
      (+) PSCM_B (C1463B) Connector, Harness Side DLC (C251) Connector, Harness Side
      (-)
      CAN- - VDB26 (GRAY/BLUE) - Pin 3 CAN- - VDB05 - Pin 19
      CAN+ - VDB25 (GREEN/ORANGE) - Pin 2 CAN+ - VDB04 - Pin 20
    • Are the resistances less than 3 ohms? 
      Yes No
      Go to  AH4. REPAIR the circuit.
  4. AH4: RECHECK FOR PSCM DTC U0100 
    • 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.
    • DLC connector connected. (C251) 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 U0100 currently present and active in the PSCM? 
      Yes No
      The PSCM HS-CAN circuits are working correctly at this time. RETRIEVE and RECORD all PCM DTCs.
      REFER to the ELECTRONIC ENGINE CONTROLS - 3.5L ECOBOOST (272KW/370PS) and DIAGNOSE the PCM.      		 If the PSCM no longer lists DTC U0100, the concern was repaired during this pinpoint test and the PSCM HS-CAN circuits are working correctly at this time.
scientia non olet · About LEMON Manuals