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Pinpoint Test H: DTC P166B

  1. Refer to Wiring Diagrams Transmission Controls - 8F57 for schematic and connector information.

    Normal Operation and Fault Conditions 

    The GSM uses the drivers door unlock switch input and drivers door status input to shift the transmission into the park position when the operator is preparing to exit the vehicle.

    DTC Fault Trigger Conditions 

    DTC Description Fault Trigger Condition
    GSM P166B:00 Drivers Door Status Correlation: No Sub Type Information The GSM monitors the voltage signals on the door status and door unlock switch inputs. If these inputs fail a rational test between them, the DTC sets.

    Possible Sources 

    • Connectors damaged or pushed-out terminals, circuitry open, shorted to power or shorted to ground
    • Driver door lock/unlock switch
    • Driver door ajar switch
    • GSM

  2. H1 RUN GSM SELF-TEST AND RETRIEVE AND RECORD ALL DTCS

    • Ignition ON.

    • NOTE: If a GSM self-test is performed, the driver door must be closed and locked. A false P166B DTC sets if the driver door is opened or unlocked during the self-test. Do not apply the brake pedal during the self-test.

      Using the diagnostic scan tool, run the GSM self-test and retrieve all DTCs.

    Is DTC P166B present? 

    Yes  GO to  H2
    No  The system is operating correctly at this time.
  3. H2 MONITOR THE DOOR UNLOCK/LOCK PID

    • Using the diagnostic scan tool, monitor the GSMPID, DR_UNLCK_HWI while locking and unlocking the driver's door.

    Does the PID toggle while locking and unlocking the driver's door? 

    Yes  The system is operating correctly at this time.
    No  GO to  H3
  4. H3 CHECK THE DOOR UNLOCK CIRCUIT FOR AN OPEN

    • Ignition OFF.

    • Disconnect GSM C2503.

    • Disconnect Driver Door Ajar Switch C573.

    • Inspect the connectors for damaged or pushed-out terminals.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2503-4
      GFD596559Courtesy of FORD MOTOR COMPANY
      C573-2

    Is the resistance less than 3 ohms? 

    Yes  GO to  H4
    No  REPAIR the circuit.
  5. H4 CHECK THE DOOR UNLOCK CIRCUIT FOR A SHORT TO GROUND

    • Connect Driver Door Ajar Switch C573.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2503-4
      GFD596559Courtesy of FORD MOTOR COMPANY
      Ground

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to  H5
    No  REPAIR the circuit.
  6. H5 CHECK THE DOOR STATUS CIRCUIT FOR AN OPEN

    • Disconnect BCM C2280D.

    • Inspect the connector for damaged or pushed-out terminals.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2503-15
      GFD596559Courtesy of FORD MOTOR COMPANY
      C2280D-33

    Is the resistance less than 3 ohms? 

    Yes  GO to  H6
    No  REPAIR the circuit.
  7. H6 CHECK THE DOOR STATUS CIRCUIT FOR A SHORT TO GROUND

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2503-15
      GFD596559Courtesy of FORD MOTOR COMPANY
      Ground

    Is the resistance greater than 10, 000 ohms? 

    Yes  GO to  H7
    No  REPAIR the circuit.
  8. H7 CHECK THE DOOR UNLOCK CIRCUIT AND DOOR STATUS CIRCUITS FOR A SHORT TO POWER

    • Ignition ON.

    • Measure:
      Positive Lead Measurement / Action Negative Lead
      C2503-4
      GFD596560Courtesy of FORD MOTOR COMPANY
      Ground
      C2503-15
      GFD596560Courtesy of FORD MOTOR COMPANY
      Ground

    Is any voltage present? 

    Yes  REPAIR the circuit.
    No  GO to  H8
  9. H8 VERIFY THE GSM FAULT

    • Ignition OFF.

    • Connect BCM C2280E.

    • Connect Driver Door Ajar Switch C526.

    • Connect GSM C2503.

    • Ignition ON.

    • NOTE: If a GSM self-test is performed, the driver door must be closed and locked. A false P166B DTC sets if the driver door is opened or unlocked during the self-test.

      Using the diagnostic scan tool, run the GSM self-test and retrieve all DTCs.

    Is the concern still present? 

    Yes  INSTALL a new GSM. REFER to: Gear Shift Module (GSM) 
     
    No  The system is operating correctly at this time.