Trailer Wire Colors (97 Blazer)

[Jonesy02719]

I've tried a search for this, but had no luck.

I am trying to install a wiring harness for my boat trailer, and I need a description of the wires coming out of the rear harness. I have a 97 Blazer LT with an OEM towing package.

As far as I recollect, there's a blue, red, brown, yellow, dark green, lighter green, a larger white and a smaller white wire in the harness.

Another previous owner obviously had messed with the harness, since some of the wires are different lengths. I have no idea what wires are which, since there is no decal or anything that tell me any descriptions. Also, I do not have an owners manual for Blazer.

I tried hooking it up, but I keep blowing my 20amp brake/hazard fuse. I only blow the fuse when the trailer is hooked up. The two different white wires, and the two different green wires are my problems...

Can anyone post a description of all thge wire colors?

[Blue Bowtie]

The typical lighting colors for most GM vehiles dating back to the 1950s (your '97 Blazer included) is as follows:

Yellow - Left Turn/Brake lamp on all years;

Dark Green - Right Turn/Brake lamp on all years;

Brown - Tail/Marker lamps on all years;

White - Chassis ground on early vehicles, Center brake lamp on 1986-up vehicles. In your case, the larger white is PROBABLY the ground, and the smaller white is PROBABLY the third brake lamp;

Light Green - Back Up lamps, which may or may not be used on your trailer lighting;

The blue and red wires are not factory lighting. They may be from a brake controller or some other device.

[DelCoch]

Originally Posted by Jonesy02719

. . . previous owner obviously had messed with the harness, since some of the wires are different lengths. I have no idea what wires are which, since there is no decal or anything that tell me any descriptions. . .

Since the wires have been messed with, the color may not mean much, thus I would suggest using a test light to determine what wire is controlled by what. If your trailer is not new, you might want to use a fused 12V jumper wire to see what is what on the trailer also.

[DelCoch]

Maybe these photos will help

[Cruize]

Originally Posted by Blue Bowtie

The blue and red wires are not factory lighting. They may be from a brake controller or some other device.

It's been a couple years since I worked with trailer wiring, but I would venture a guess that the red wire could be a dedicated wire for charging a wet cell battery on a trailer (RV).