Wiring diagram for FORD F150 trailer lights from truck

you have three of the four already - so a volt meter or a 12v test lamp would indicate them for you you have a ground - the left turn/stop - the right turn/stop and the running lights

Thanks for the quick response. I have never used a forum like this and it paid off. Thanks again!!!

Ok I lied, that didnt work at all. Any other help?

Get a test light from an auto parts store. Turn on just the running/park lights on your truck. Ground your test light, then probe the wire harness at either rear light, done easiest with the taillight assembly out. When your test light lights up, you've found your running lights for your trailer. Connect it to the Brown wire on your trailer kit. If you need further you can email me direct using my knick below, then @excite.com

Spdloader

What do you mean by "that"? Are both elements in both trailer bulbs OK?

The best way to do the job is with an adapter that simply plugs into the harbess below the tailgate and is already wired correctly. Takes about 2 minutes for complete job. Almost any store that sells anything related to trailers, boats or auto parts should have the adapter. Then you won't have a sliced and diced harness to cause further problems later down the road.

Lugnut

The wire harness for a 4-pin connector is included with the connector.

WHT - Ground BRN - Lights GRN -- Right turn and stop RED - Left turn and stop

You have a wiring problem in the trailer associated with improper grounding. You described exactly the problem of a poor ground. The trailer's stop and turn lights are getting a ground WHEN THE LIGHTS ARE ON through the running light circuit in the truck. If the lights are turned off, then the brake and turn indicators stop working too. (Actually, as I write that, it occurs to me that symptoms should be exactly opposite -- the brake and turn indicators work when the lights are off, then stop working when the lights are on.)

You have a grounding problem in the trailer or you have the wrong light bulbs in the trailer. Odds favor a bad ground over the wrong bulbs. Your bulbs should have two filiments in each, and the number stamped on the base should be 1157.

On the trailer wiring harness (connector), WHT is ground. BRN is running lights, GRN is right side turn and stop, YEL is left side turn and stop. A common problem is that some guys bring the white wire into the trailer, but do not select a suitable grounding method. You must put a good terminal on the end of the wire, then use good star washers to poke through the paint and press into the metal. (Paint is an insulator.) You should really scrape the paint away from the grounding terminal to make a quality connection point. Once you have your system working, then you can come back and paint over the connection to preclude rust. It's a good idea to cover the grounding point with tape before painting, then remove the tape to establish the ground point. This is actually better than painting over a ground connection.

Then, you have to ensure that the tail light housings are grounded well to the trailer itself. This is a huge problem with trailer lights, they ground through the mounting screws to the trailer itself, but the mounting points are not qualified to provide the needed ground circuit. You might be required to hardwire a ground from the housing (lamp base) to the trailer frame. You _could_ bring the white wire from the connector all of the way to the lights, but usually the white wire terminates on the tongue and the lamp housings are then grounded to the frame of the trailer. If you wire this way, then you will have GRN and BRN to the right side, and YEL and BRN to the left side

CORRECTION TO AN EARLIER POST I might have said that there is a RED wire to serve the stop and turn indicator on the left side, this is an error, the actual wire color for that circuit is YEL.

Trailer wiring is standardized, and a 4-pin wiring harness (by far the most common) has WHT, BRN, GRN, & YEL. The arrangement of the wires in the tow vehicle is important because because one might tow a different trailer some day, and one would want any trailer to easily connect without having to rewire something everytime the trailer changes.

Most trucks already have a 4-wire plug on them, whether or not they have a trailer tow package on them. I don't recall that you mentioned which year your F150 is, but I have a '95 Bronco that has a trailer connector, and my previous '95 Bronco also had one -- they are both 6- or 7-pin designs, and could be the result of a tow package. I've been shopping for F150s in the past two or three years, and I noticed all of them on the lot that I was looking at had trailer connectors on the truck.

When you buy a flat 4-pin connector from WalMart, or anyplace else, the arrangement of the wires will always be the same, and any trailer will also be the arranged the same way. The idea is that you should be able to hook up any trailer and drive away, and the lights should work. Surely one would not want to hook up to a trailer and have it start blowing fuses in the tow vehicle, and this requires you to wire your connector the same way everybody else wires them.

The RED wire is really YEL.

The trailer wires are WHT, BRN, GRN, & YEL.

And just for informational purposes, I have always remembered the right and left this way.

Green has 5 letters, RIGHT has 5 letters

PORT has 4 letters, LEFT has 4 letters.

Brown and White also have five letters.

What has port got to do with anything? We're not lighting a boat.

brown and white were never the confusing part.

I just thought I'd throw that in about the port thing.

One can abbreviate wire colors with 3 letters and not have any danger of confusing one color with another.

Brown and white also have 5 letters. Yellow has 6 letters, and defines the brake and turn indicator wire for the left side of a trailer.

I am having trouble understanding what your point is.

You're having trouble understanding. Let's just leave it at that. I can't make it much simpler.

You offered no new information that is 1.) corrrect, or 2.) applicable.

Thanks for playing though.

PORT wine is red ;-)

Whitelightning

Look you dumass bastard. I merely made a comment as to an easy way to remember which is which between the green and yellow on trailer light wiring.

So Fuck off.

Except, your easy way to remember is WRONG. GRN is right, YEL is left.

I see no need for profanity.

And, it's dumbass bastard, dumbass.