Wiring Quiz

[Ami P]

Confusing wiring colors...The wiring diagram is clear at the tail end of my UHaul, it is easy enough to trace the tail, turn/stop and the ground. The first hurdle arrives in a rainbow of colors, inconsistently routed. The reality at the tongue-end is absurd: I have a left harness with three wires - White, Black and Green. I also have a right harness with three wires - White, Black and Green. (Yes, the same three colors on both sides. ) Does anyone have any ideas how to unscramble this into a flat 4. (The ground is obvious everywhere.) Thanks - Ami P

[James Harper]

one for each side....hook the grounds togather along with the running lights...the turn sing wires will stay seperate

[Ami P]

one for each side....hook the grounds togather along with the running lights...the turn sing wires will stay seperate

Which color, would you suggest as the separate turn signal wires? Brown or green?

[James Harper]

the green should be for your turn lamps. wires in 4 the wire in front should be ///1 side brown other green ....white ground..black running lights..Ill check in the morning and let you know which is left and right

[ERIC B.]

In a typical four-flat connector: white is ground, brown is running lights, yellow is left turn, and green is right turn. Connect them to the appropriate wires coming from the rear (disregarding color- using function only). Hope this helps!

[Ami P]

Perhaps I was not clear enough.
Facts:
1. I have differrent colors going into the harness at the tail than the colors exiting at the tongue harness
2. I have the same three colors on both R and L exiting at the tongue harness [Black, White and Green] no Brown, no Yellow
3. I know the functions and correct colors on a standard flat 4
4. The only wire on the trailer that is consistent and known is ground (White)
5. I know that tail/running lights are joined at the trailer flat 4

Issues:
A. How do I determine which wire is L Turn, R Turn at the tongue?
B. Which is brake?
C. Which is tail/running lights?

Thanks

[Paul from NWOnt]

Pull the taillight lenses, and bulbs. Get a 12v battery and hook it up to the light sockets making the appropriate connections. Use a testlight on the front end to determine which wires are doing what.

With this method, every wire could be the same colour and you'd still be able to easily figure it out.

[Joe MacDonald]

do some temporary wiring.
connect a jumper from a flat four plug at the tow vehicle on the ground wire to the trailer ground.
put your vehicle park lights on, and connect the brown from the Tow to one of the green wires at the tongue with a jumper, and go to the back , see which light comes on. Mark the wire with a piece of masking tape and move on too the next wire. when you have all the wires tested, you can join the running lights together, and leave the signal/brakes separate and connect to a new flat four plug. Then off you go!

[Ami P]

Great, I'll try it. I am checking for wiring shorts. Should I be getting ohm readings when grounding positive wires? (tail, turn, brake)

[Darwin Maring]

I strongly suggest that you get some help from someone that is familiar with trailer wiring or Call your local UHAUL dealer to see if they will sort it out 4 U.