I'm lost in how this should be done. I want to wire up a trailer hitch brake light. I see on my blazer and all alike that the brake light is also the turn signal. Do I run a positive feed off the brake switch under the pedal or is there another way to do it? Thanks for the help

 

First thing I'd do is check to see if you have a harness for this already tucked up under the back of your truck somewhere...

I'm assuming you have an Xtreme based off of your screen name, but please do give us details as to what you have.

 

i believe most trailer hitch brake lights come with it's own wiring receptor to accept your vehicle's standard trailer wiring harness plug. if trailer hitch light came with instructions, follow them closely. another way is to tap into the brake light wire harness behind one of the removable brake/tail light assemblies and run hot wireto trailer hitch light, whichmay then need to be grounded.
good luck
laserblazer

 

I do not believe that any s-series blazer came from the factory with a trailer plug. They were addons after purchase. Most blazers have the harness tucked up under the back of the truck somewhere. I know on the 4doors, its on the rear crossmember to the drivers side, but I think it's different on a 2door.

 

I looked everywhere under the truck for a harness and can't find anything. The brake light came with a built in 4 prong flat harness. It says one wire is for ground, one wire is for tail, one is for left turn, and the last is for right turn.

The problem is I just want it to turn on when I hit the brakes. but when I hit the brakes the same light is for the turn signal.

 

The harness is not going to have an end on it already it is just a blunt end and you will need to add a connector, it should be tapped up and with a white tag on it that will tell you what wire does what. In my harness I know that it had a wire for the HMSL (High Mounted Stop Lamp)which will give you just the brake input you are looking for. Good luck, keep looking.

 

I found it. I was looking at it the entire time but the way its wrapped looked like it was connected to something. I plugged it all in and is working great. Thanks for the help.