Troubleshooting Trailer Connector On 2005 Nissan Titan

Updated 03/21/2015 | Published 03/20/2015

Products Featured in This Question

Pollak 7 Pole to 4 Way Connector Adapter

(1064)

$10.22

Hook Probe Circuit Tester

(66)

$14.40

Question:

I have a 2005 Nissan Titan Off Road with tow package I recently purchased. I have a utility trailer with a 4 pin flat connection and the truck has a 7 pin round. I bought a new adapter and nothing on the trailer works w/ a new light kit. The adapter has LED tester lights on it. W/O the trailer hooked up the tester lights work as they should, but when the trailer is hooked up all three tester lights flash, but nothing on the trailer. Ive tried new plugs, another set of lights, made sure the ground connections were good, to no avail. Thoughts?

asked by: Jason D

Expert Reply:

I wouldn't necessarily trust the adapter or the LEDs on it. Remove the adapter and use a circuit tester like part # PTW2993 on the pins of the 7-way as each taillight function is activated. Turn on the headlights and test the pin at the 11:00 position. Then activate the right turn signal and test the pin in the 3:00 position. Turn on the left turn and test the pin at 9:00. Each pin should make the tester illuminate as its function is activated. Then, plug in the adapter, attach the clip to the male pin of the adapter. Test the first socket with the running lights, the next with the left turn and the remaining socket with the right turn.

If the connector on the vehicle tested okay, but not the adapter, the adapter is faulty and should be replaced. I'd recommend the # PK12716. If the adapter checks out okay, then the wiring problem exists somewhere on the trailer. Have you tried plugging a different trailer into the truck? This would be a quick way to track down whether the vehicle or the trailer is causing the problem.

You'll need to recheck the wiring on the trailer, starting with the connector. Make sure it's in good condition, with no corrosion or damage. Make sure the white ground wire is tightly connected to the trailer tongue, and that the connection point isn't corroded. Trace each wire to its lamp, looking for loosed or pinched wires. Make sure each lamp is grounded either by its own ground wire or by its direct attachment of its mounting studs to the trailer frame.

I've linked you to our Trailer Wiring FAQ article, as well as our Trailer Wiring Troubleshooting article, which you should find very helpful.

expert reply by: Mike L