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

WARNING: This page is about a different car, the 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.

D1 CHECK FOR VOLTAGE THROUGH THE TRAILER TOW CONNECTOR

Ignition OFF.

Disconnect: Trailer.

Ignition ON.

Place the headlamp switch in the PARKING LAMPS position.

If equipped with a 4-pin connector only, measure:

Positive Lead	Measurement / Action	Negative Lead
C4098-3	Courtesy of FORD MOTOR COMPANY	Ground

If equipped with a 4-pin and 7-pin connector, for 4-pin connector, measure:

Positive Lead	Measurement / Action	Negative Lead
4-Pin Connector, Pin 3	Courtesy of FORD MOTOR COMPANY	Ground

If equipped with a 4-pin and 7-pin connector, for 7-pin connector, measure:

Positive Lead	Measurement / Action	Negative Lead
7-Pin Connector, Pin 6	Courtesy of FORD MOTOR COMPANY	Ground

Place the headlamp switch in the OFF position.

If equipped with a 4-pin connector only, measure:

Positive Lead	Measurement / Action	Negative Lead
C4098-3	Courtesy of FORD MOTOR COMPANY	Ground

If equipped with a 4-pin and 7-pin connector, for 4-pin connector, measure:

Positive Lead	Measurement / Action	Negative Lead
4-Pin Connector, Pin 3	Courtesy of FORD MOTOR COMPANY	Ground

If equipped with a 4-pin and 7-pin connector, for 7-pin connector, measure:

Positive Lead	Measurement / Action	Negative Lead
7-Pin Connector, Pin 6	Courtesy of FORD MOTOR COMPANY	Ground

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

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

No	If equipped with a 4-pin connector only. If the trailer parking lamps are inoperative, GO to D3. If equipped with a 4-pin and 7-pin connector. If the trailer parking lamps are inoperative, GO to D2. If the trailer parking lamps are always on, GO to D7

D2 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR (VEHICLE HARNESS)

Ignition OFF.

Disconnect: Trailer Tow C4099.

Ignition ON.

Place the headlamp switch in the PARKING LAMPS position.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4099-6	Courtesy of FORD MOTOR COMPANY	Ground

Is the voltage greater than 11 volts?

Yes	INSTALL a new trailer tow connector. TEST the system for normal operation.

GO to D3

D3 CHECK THE TRAILER TOW PARKING LAMPS RELAY CONTROLLED GROUND CIRCUIT FOR GROUND WITH PARKING LAMPS ON

Place the headlamp switch in the OFF position.

Ignition OFF.

NOTE: To access the BJB connectors, the bottom cover of the BJB must be removed.

Disconnect: BJB C1035C.

Ignition ON.

Place the headlamp switch in the PARKING LAMPS position.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Battery Positive	Courtesy of FORD MOTOR COMPANY	C1035C-27

Is the voltage greater than 11 volts?

Yes

GO to D6

GO to D4

D4 CHECK THE TRAILER TOW PARKING LAMPS RELAY CONTROLLED GROUND CIRCUIT FOR A SHORT TO VOLTAGE

Ignition OFF.

Place the headlamp switch in the OFF position.

Disconnect: BCM C2280F.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2280F-12	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR the circuit.

GO to D5

D5 CHECK THE TRAILER TOW PARKING LAMPS RELAY CONTROLLED GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2280F-12	Courtesy of FORD MOTOR COMPANY	C1035C-27

Is the resistance less than 3 ohms?

Yes

GO to D10

No	REPAIR the circuit.

D6 CHECK THE TRAILER TOW PARKING LAMPS RELAY OUTPUT CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: BJB C1035D.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4099-6	Courtesy of FORD MOTOR COMPANY	C1035D-3

Is the resistance less than 3 ohms?

Yes	INSTALL a new BJB.

No	REPAIR the circuit.

D7 CHECK THE TRAILER TOW PARKING LAMPS RELAY CONTROLLED GROUND CIRCUIT FOR GROUND WITH PARKING LAMPS OFF

Place the headlamp switch in the OFF position.

Ignition OFF.

NOTE: To access the BJB connectors, the bottom cover of the BJB must be removed.

Disconnect: BJB C1035C.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Battery Positive	Courtesy of FORD MOTOR COMPANY	C1035C-27

Is any voltage present?

Yes

GO to D8

GO to D9

D8 CHECK THE TRAILER TOW PARKING LAMPS RELAY GROUND CIRCUIT FOR A SHORT TO GROUND

Ignition OFF.

Disconnect: BCM C2280F.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C2280F-12	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance greater than 10, 000 ohms?

Yes

GO to D10

No	REPAIR the circuit.

D9 CHECK THE TRAILER TOW PARKING LAMPS RELAY OUTPUT CIRCUIT FOR A SHORT TO VOLTAGE

Place the headlamp switch in the OFF position.

Ignition OFF.

Disconnect: If equipped, TRM C2498C.

Ignition ON.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C1035C-27	Courtesy of FORD MOTOR COMPANY	Ground

Is any voltage present?

Yes	REPAIR the circuit.

No	INSTALL a new BJB.

D10 CHECK FOR CORRECT BCM (BODY CONTROL MODULE) OPERATION

Disconnect and inspect all BCM 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 BCM 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, Refer to BCM GUIDED ROUTINE .

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.