Pinpoint Test V: The Trailer Lamps Are On Continuously

WARNING: This page is about a different car, the 2008 Ford RV Cutaway, 2008 Ford Econoline, 2008 Ford E450 Super Duty, and 2008 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

V1 CHECK FOR VOLTAGE TO THE TRAILER TOW CONNECTOR

Key in OFF position.
Disconnect the trailer from the vehicle.
Key in ON position.

Measure the voltage between the trailer tow connector, harness side and ground as follows:

Trailer Connector-Pin	Circuit
4-Pin Connector
C4098-2 (parking lamps)	962 (BN/WH)
C4098-3 (LH stop/turn lamp)	52 (YE)
C4098-4 (RH stop/turn lamp)	64 (DG)
7-Pin Connector
C4099-6 (parking lamps)	962 (BN/WH)
C4099-1 (LH stop/turn lamp)	52 (YE)
C4099-4 (RH stop/turn lamp)	64 (DG)
C4099-7 (reversing lamps)	963 (BK/LG)

Is any voltage present?

YES : Go to V2.
NO : The vehicle is operating correctly. SEND the trailer to an authorized camper/trailer repair facility.

V2 CHECK THE TRAILER TOW RELAY

Disconnect: Suspect Trailer Tow Relay

Measure the voltage between the trailer tow connector, harness side and ground as follows:

Trailer Connector-Pin	Circuit
4-Pin Connector
C4098-2 (parking lamps)	962 (BN/WH)
C4098-3 (LH stop/turn lamp)	52 (YE)
C4098-4 (RH stop/turn lamp)	64 (DG)
7-Pin Connector
C4099-6 (parking lamps)	962 (BN/WH)
C4099-1 (LH stop/turn lamp)	52 (YE)
C4099-4 (RH stop/turn lamp)	64 (DG)
C4099-7 (reversing lamps)	963 (BK/LG)

Is any voltage present?

YES : REPAIR the circuit in question for a short to voltage. TEST the system for normal operation.
NO : INSTALL a new trailer tow relay for the one in question. TEST the system for normal operation.