Trailer Brakes

[Shorty]

I have a 1986 GW and with an adapter on the connector under the rear bumper I have been able to pull a boat and provide proper signal to the boat trailer. I have recently purchase a trailer which has electrial brake. I have a box mounted under the rear bumper which I thought would provide the proper signal to the trailer. I have a new adapter (9 pin circular plug) and I am looking for the proper brake signals. All other signals work OK. However, the pin, where the brake signal should be is not there. Here are the questions: (1) Where can I find the schematic of that box mounted near the rear bumper? (2)Even if some voltages where present on the brake pin, how would I adjust the voltage level for the trailer. (3) Do I need to go to UHaul It and purchase the whole system?
Thanks,
Shorty

[Jim Barbero]

Usually a trailer brake is not built into the connector under the rear bumber. Normally there will be a unit on or under your dash that controlls the voltage to the electric brakes on a trailer (if so equipped).

If it is an aftermarket trailer plug under your rear bumper, normally
Brown - Taillights
Yellow - Left turn/brake
Green - Right Turn/Brake
White - Ground
Blue - Trailer Brakes
However, if it was done by a previous owner, they may not have followed these exactly (or at all)

If it is a factory option, I don't know the color coding, but I am sure someone here will offer more info.

[Jim Barbero]

Oh, and welcome to the best place to find info on these beasts.

[porchpiggy]

You have to wire the brakecircuit in yourself. There are basicly two types of modern brake controlers, the "inertia" type and the "timed" type. I prefer the inertia type, which uses a combination of a signal from your brake light switch and inertia from you stopping, to senf electrical current to your trailer brakes. The more brake is applied, the more current issent. The timed type uses a combination of time and asignal from your brake light switch. Te longer you hold the brakes on the stronger the signal becomes, adding more trailer brakes. Thebrake controller costs about $50 to $150 dolars, and is easy to wire in. You will have four leads, one to pos, one to neg, one to the brake light switch by your brake pedal, and one to the trailer plug. The wire to your trailer plug, and on your trailer to thebrakes, is usually blue. I'm very familiar with the 7 blade RV plug used on Rec Vehicles, but have never seen a 9 pin plug. Whichever controller you buy will have comlpete instructions, and it is really very easy. The controllers adjust for number of brakes, and how fast the brakes will increase. The inertia typewill also have an adjust ment for "level". The instructions are very complete for all the adjustments. Most controllers also have a manual over ride, which is great for when trucks pass you and get the trailer to fishtail, you just tap your trailer brakes and it straightens right out. Once you tow with trailer brakes, you will never want to be without them. Also, most plug wiring is "standard", and youcan get a diagram from the back of the package a plug comes in. :cool: