Pinpoint Test H: DTC P166B

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

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.

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

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	Courtesy of FORD MOTOR COMPANY	C573-2

Is the resistance less than 3 ohms?

Yes

GO to H4

No	REPAIR the circuit.

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	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes

GO to H5

No	REPAIR the circuit.

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	Courtesy of FORD MOTOR COMPANY	C2280D-33

Is the resistance less than 3 ohms?

Yes

GO to H6

No	REPAIR the circuit.

H6 CHECK THE DOOR STATUS CIRCUIT FOR A SHORT TO GROUND

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2503-15	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes

GO to H7

No	REPAIR the circuit.

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	Courtesy of FORD MOTOR COMPANY	Ground
C2503-15	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR the circuit.

GO to H8

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.