Wiring Trailer Lights

This is probably an odd request, but has anybody ever wired up trailer lights on a pull behind trailer? Let me explain. My boss man has two trailers, one is a boat trailer that he wanted harnesses put on so he could hook it to his 97 blazer. He also wanted the harness put on the blazer to plug into the trailers. The trailers each have one light on each side with power and ground for each. The harnesses I bought each have 4 wires on them: ground, taillight, left blinker, and right blinker. This is simple enough. But if you just hook these wires to the corresponding wires on the truck, the lights on the trailer will not perform the way I want them to. Since the tail light wire from the harness has to be wired to both lights, you have to diode isolate them and hook the blinker wires after the diodes. This works perfectly as long as the taillights are not on. In this case the blinkers won't blink because they get constant power. I can fix this with relays, but I keep thinking that it should not be this complicated. I've seen several of these harnesses already installed, and I've never noticed diodes or relays on them. I'm wondering if there is somewhere on the truck where these wires will already be isolated so I don't have to do all this. Any suggestions?

Go to the dealer and get a tralier wiring harness for the vechiel it will go ethier under the dash or hood and run to the back. It will have all the wires you need and it work right.

Go to, www.campingworld.com They have just about every type of trailer harness and accessory known to man and god. Good luck!R Jackson

Owner/Installer

TRM Emergency Vehicles

Information is advice only and should be confirmed with OEM or quality test equipment.

Boyertown, Pennsylvania

I think you are missing the ground. if you have two wires coming out of the lights, one will be tail/park lights, and the other will be stop/turn. The light is grounded internally through one of the bolts. Some of the lights that I have seen have one red, and one black, but yours may be different. if it does, wires as follows: Take your brown, and run it to both blacks. Take your yellow and run it to the left red. Take your green and run it to the right red. Take your white and run it to frame on the trailer.

IF you do not want to splice into your existing wires, AutoZone and some other local Auto parts stores sell a harness. The OE lights plug into the harness, then harnesses plugs into the OE lights with the colored wires hanging off for you to connect the Exterior connector to. There are two different kinds of trailer lights! You have the Driving, Signal/Brake combo, and Driving, Signal, Brake, Reverse types. The BASIC is just FOUR wires; Driving (connects to either side), Signal/Brake (left/right) & Ground. IF you have SEPERATE signal and brake lamps, you need the other wire scheme. If your brake lights are also your signal lights, then the basic four wire deal is fine, which is what I use in my Dodge Avenger. There is no reverse set-up in the basic set-up either.

He said he had a 97 blazer, and the trailers have one light per side.

The two wires are for the lights. One is power and the other is ground. The lights do not ground through a bolt on this trailer.   Thanks everybody.

Yeah, if the lights do not ground when bolted to the trailer, then you will need to ground them. My trailer is very old, and I am just happy there's still metal for it to ground to. Hecj, my boat is old also, 1962 Sefair Sedan, nice, but old. . . I bought all new lights and wiring. Was pretty simple to do, but I spliced into the wires instead of buying the Harness for INSIDE the trunk. Would have made it all look better, but, it works.

So they are only single filament bulbs? (1156)

I need some help with the trailer plug on my truck,   I never had one so I bought the 4 wire plug to put on my truck thru the taillight wires, but they keep messing up!!   I have a black wire in each tailight, a turn signal wire and a tailight wire.   I hooked the turn siganl wires up right and the brown wires for the tail lights up, then grounded everything to a clean ground on  the truck , and they work perfectly during the day, but when I turn my lights on at night and hit my brakes, I lose my taillights and brake lights on the trailer, but still have turn signals!? Anybody have any ideas on how to fix this problem??