View Full Version : Trailer Light Trouble (long)

The Wizard
09-23-2008, 05:00 PM
I have been struggling with this problem all summer. I have a 1994 D90 that has the Land Rover 7-pin trailer receptacle installed and the adapter to go from a 7-pin to a flat 4 trailer plug. Now, with the adapter plugged into the 7-pin receptacle and using a test light everything work as it should work! So far so good!

Hook up the trailer, plug the trailer's wiring into the flat 4 of the adapter which in turn is plugged into the D90's 7-pin receptacle and everthings goes goofy! First, the D90's backup light comes on when any of the other lights come on(turn signals, brake or running). Both turn signal lights and the running lights on the trailer are very dim. Brake lights seem to be of the correct brightness. Leave/play with the lights long enough and the fuze for the backup light circuit, which by the way is also the circuit for the windshield wipes(the manual does not mention that), blows! At which time things start to work alright, except I don't have a backup light or windshield wipers.

Before you said it is the trailer, I have hooked this trailer up to a half dozen other vehicles and it works perfectly hooked up to them. I have spent hours checking the wiring on the trailer and it checks out fine!

Finially, I looked behind the rear passenger side speaker where the converter "box" for the trailer connector is located. Going out of the "box" are 4 wires: white (ground), brown (tail/parking), green (right turn/brake)and yellow (left turn/brake). Wires going into the "box" are white, yellow, black and green. The white is connected to 2 red/brown wires. The black is connected to 2 red/black wires. The yellow is connected to 2 red/green wires. The green is connected to 3 wires: a large gauge green/purple wire, a small gauge green/purple wire and a red wire. I have no idea what should be going on back there.

This is turning into rocket science when it should be simple electricity.

Maybe the D90 just doesn't like/want to pull a trailer! That is it, the D90 doesn't like the trailer!

09-27-2008, 07:52 AM
The Defender is still a foreign vehicle and you must buy a trailer light adapter to make it work on a four pin. The adapter they sell is very misleading but the parts work together with the light adapter.