PINPOINT TEST AH : All The Trailer Lamps Are Inoperative

NOTE: Before beginning diagnostics, visually inspect the trailer tow connector mounted on the bumper for signs of corrosion or damage. Repair or install a new trailer tow connector as required.

AH1 CHECK THE RELAY GROUND CIRCUIT FOR AN OPEN

Ignition OFF.

Disconnect: Trailer Tow Parking Lamp Relay.

Measure:

Positive Lead	Measurement / Action	Negative Lead
Trailer Tow Parking Lamp Relay Pin 3 Courtesy of FORD MOTOR COMPANY	Courtesy of FORD MOTOR COMPANY	Trailer Tow Parking Lamp Relay Pin 1 Courtesy of FORD MOTOR COMPANY

Is the voltage greater than 11 volts?

Yes	GO to AH2.
No	REPAIR the circuit.

AH2 CHECK THE TRAILER TOW GROUND CIRCUIT FOR CONTINUITY TO GROUND

For the 4-pin connector, measure:

Positive Lead	Measurement / Action	Negative Lead
C439-4	Courtesy of FORD MOTOR COMPANY	Ground

For the 7-pin connector, measure:

Positive Lead	Measurement / Action	Negative Lead
C4099-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes	The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.
No	For the 4-pin connector, REPAIR the trailer tow connector ground circuit for an open. For the 7-pin connector, GO to AH3.

AH3 CHECK THE TRAILER TOW GROUND CIRCUIT FOR AN OPEN

Disconnect: Trailer Tow Connector.

Measure:

Positive Lead	Measurement / Action	Negative Lead
C4099-2	Courtesy of FORD MOTOR COMPANY	Ground

Is the resistance less than 3 ohms?

Yes	INSTALL a new trailer tow connector. TEST the system for normal operation.
No	REPAIR the circuit.