The PO of my Blazer put on a class two hitch, but didn't do anything for the wiring. In decoding the RPO #'s I found: UY7 WIRING HARNESS , "TRUCK TRAILER, HD". I also scouted things under the rear bumper and found a wire loom that dead ended. Is this the trailer wiring? I would think GM engineers would leave a pig tail for trailer wires to be added.

 

yeah that should be the trailer wiring. should be 7 wires in the loom. I just did this the other day. I got a 7 wayRV plug, drilled out that hole by the lisence plate with a hole saw, and just bolted it on. It was alot easier than i thought...

 

Take a look in your owners manual for the wiring identification information.

 

there was just a thread on this kinda not to long ago i dont remember the name of the thread tho it was by a_tack in the general chat i believe

 

That's what I did, too!

But only really useful on a 2 door, otherwise you won't be able to get your spare tire on a 4 door.


I'd reccomend going to a class 3/4 hitch, unless you never tow anything heavy.

 

ha ha thats true. yeah don't drill out that hole if your spare is underneath!!!

 

my wiring thread was about a poor ground on a utility trailer... but I can answer this one..lol

if you are not towing anything heavy then just put on a 4-flat plug...

peel back the tape on the loom and there should be 7 wires.. the colors are as follows..

Yellow-left turn
Green-right turn
Brown-tail/stop
White-ground

(you will only need those four for a 4-flat plug)
If you insist on a 7 prong RV setup, then you will need the other 3 wires and a bigger hitch as a class 2 is not rated to pull anything big enough to use trailer brakes... the others are..

Orange-auxillary power (batt. charger on camper, etc..)
Blue-Trailer Brakes
and I think Purple(may be another color, but no color is in there twice)-Reverse lights


hope this helps, but I would seriously consider changing hitches to a class 3, 2" reciever because your blazer will tow more than a class 2 is rated for!


all of these wires are already tapped into the trucks electrical system. All you need to do is add the desired plug. If you get a 7-prong RV plug and wish to add trailer brakes, after wiring it properly you should be able to get a brake balance controller and the proper harness and just plug it in under the dash..


I have a class 3 hitch and a 4-flat plug. I never pull a trailer that breaks 3000lbs (bass boat)... and driving properly, your blazer's factory 4-wheel disc will stop a trailer that size with no problem..

 

Not that I'm going to use them; but is the trailer brake tied to the Blazers brake circuit? Or is an additional trailer brake unit needed?

I will only be towing my motorcycles and trailers under 1150 GVW. I don't think I'd want to tow anything heaver.

 

You'd need a brake controller... And you'll only have the brake controller wire going under the dash if you have the towing package, I believe.

Also, the orange wire is only there if you have the towing/trailer package...

The hitch should have its weight ratings on it somewhere...

For that amount of weight, you should be good... But I'd double check.

 

Cool! Yea I had a class 4 hitch on my old K1500, and pulled a friends Sallien to Mid-Ohio Sports Car Course many a time. I had a nice adjustible controler for that. I forgot to look for a class rating on the Blazer's hitch. Will do. Thanks again all!