7 (or 8) pin trailer wiring
 

I have a 1999 4dr 4wd blazer and recently got a trailer that requires a seven pin connector looked in the owners which told me the color scheme for all the wires ( there were 6 at the back) but it said that 2 of the ones there as well as two that weren't were only if the 7 pin wiring option was on my vehicle.
when i looked under the hood @ the fuse block it has fuses for all of the wires including the trailer battery charge and brake controller.

so i guess this is a two sided question. first if the fuses are present does this mean the wires are there somewhere or does it just mean they filled the spots (there are empty spots for extras that mine doesn't come with). and if the wires are there does this mean it has a integrated brake controller or do i still have to purchase a after market one

was hoping someone else has had a similar experience

thanks
graham

The s-series trucks never had an integrated trailer brake controller. You must add one if you need trailer brakes.

As covered in quite a few threads on the subject, all you have to do is look inside the rear frame crossmember to find the factory wiring if your truck was so configured. RPO code UY7 is for the heavy duty trailer wiring harness.

thanks for the info on the brake controller

i knew that the wiring was under the rear frame rail and thanks for the info on the heavy duty harness number.

later
graham
welp
ellis

I love my Tekonsha P3 brake controller. Picked it up from AdventureRV.net for $115. Works great with my 2003 Starcraft TravelStar 19CK trailer. If you have the heavy duty harness, you will have all of the wiring tucked under the dash for the brake controller as well.