Pinpoint Test C : The Trailer Parking Lamps Are Inoperative Or Always On

WARNING: This page is about a different car, the 2018 Ford EcoSport. However, it is still accessible from the selected car via links, so may be relevant.

C1 CHECK THE TRAILER TOW CONNECTOR FOR PARKING LAMPS CIRCUIT OPERATION

Ignition OFF.

Disconnect: Trailer.

Ignition ON.

Using a diagnostic scan tool, perform the TRM self-test.

Clear the Diagnostic Trouble Codes (DTCs) and repeat the self-test (required to enable the lamp output driver).

Place the headlamp switch in the PARKING LAMPS position.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Trailer tow connector parking lamps circuit	Courtesy of FORD MOTOR COMPANY	Ground

Place the headlamp switch in the OFF position.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Trailer tow connector parking lamps circuit	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts when the headlamp switch in the PARKING LAMPS position and 0 volts when the headlamp switch in the OFF position?

Yes	The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.

No	If a trailer parking lamps is inoperative, GO to C2 If a trailer parking lamps is always on, GO to C4

C2 CHECK THE PARKING LAMPS OUTPUT CIRCUIT FOR A SHORT TO GROUND

Ignition OFF.

Disconnect: TRM C4397C.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Trailer tow connector parking lamps circuit	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes

GO to C3

REPAIR the circuit. After the repair: If no Diagnostic Trouble Codes (DTCs) are present, TEST the system for normal operation. If any TRM Diagnostic Trouble Codes (DTCs) other than DTC U3000:49 are present, CLEAR the Diagnostic Trouble Codes (DTCs), REPEAT the self-test (required to enable the lamp output driver) and cycle the ignition OFF and ON. TEST the system for normal operation. If DTC U3000:49 is present, INSTALL a new TRM. REFER to: Trailer Module (TRM) .

C3 CHECK THE PARKING LAMPS OUTPUT CIRCUIT FOR AN OPEN

Measure:

Positive Lead	Measurement / Action	Negative Lead
Trailer tow connector parking lamps circuit	Courtesy of FORD MOTOR COMPANY	C4397C-3

Is the resistance less than 3 ohms?

Yes

GO to C5

No	REPAIR the circuit.

C4 CHECK THE PARKING LAMPS OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE

Ignition OFF.

Disconnect: TRM C4397C.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Trailer tow connector parking lamps circuit	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR the circuit.

GO to C5

C5 CHECK FOR CORRECT TRM (TRAILER MODULE) OPERATION

Disconnect and inspect all TRM connectors.

Repair:
- corrosion (install new connector or terminals - clean module pins)
- damaged or bent pins - install new terminals/pins
- pushed-out pins - install new pins as necessary

Reconnect the TRM connectors. Make sure they seat and latch correctly.

Operate the system and determine if the concern is still present.

Is the concern still present?

Yes	CHECK OASIS for any applicable Technical Service Bulletins (TSBs). If a TSB exists for this concern, DISCONTINUE this test and FOLLOW TSB instructions. If no Technical Service Bulletins (TSBs) address this concern, INSTALL a new TRM. REFER to: Trailer Module (TRM) .

No	The system is operating correctly at this time. The concern may have been caused by module connections. ADDRESS the root cause of any connector or pin issues.