ot need some older info

ericlb · Jan 12, 2016

ive got some questions on trailer brakes, this will be on the old style with the hydraulic line to the master cylinder, still working on a 1980 chevy , im trying to get these trailer brakes working again, obviously it worked at one time,as this truck pulled a trailer which was twice too big for it, for the previous owner. online the wires diagram says blue should go to the trailer plug, it at least heads in that direction on this truck, but it says black is ground and red is battery power, what this truck has is red, has never been used, its cut short and taped up, old tape, the black goes to some add on relay on the inner fender but the wire on the other terminal of the relay is missing now, so before i put power to this relay or even the black wire, what do you guys think? running the wires backward with the metal case of the brake controller as ground?, should i start over using red as battery power? brake controller should still work, as the handle does move when the service brakes are applyed

Paul Janke · Jan 12, 2016

If I remember correctly, the controller needs a hot wire in and two wires out. One of the outs is to the electric brakes on the trailer and the other is to the brake lights on the towing vehicle. I used to put a fuse in the wire to the brake lights with a lighter-than-called-for fuse and tied that in to the switched side of the truck's brake light switch. I replaced the truck brake light fuse with a lighter one so that the circuit had some protection rather than two fuses in parallel, both of which were normal amperage. If I remember correctly, I probably used fuses about 3/4 of what was called for so I ended up with about one and a half times what the truck was designed for. Whatever I did, it seemed to work fine.

jon f mn · Jan 12, 2016

The red is power and should go directly to the battery with a 30 amp breaker, not a fuse. The other large wire is ground and there should be a small wire to hook to the brake lights altho I don't remember the color.I would also run the ground direct to battery for best results.

T.R.K. · Jan 12, 2016

Paul describes the brakes that were on my '84 GMC. It was a Kelsey Hayes controller.

One wire with circuit breaker from battery positive.
One wire to brakes.
One wire for brake lights. (I didn't use this, just tied the trailer brakes to the truck system and used a heavy duty flasher. Never had any problems).

You can probably figure out which wires do what on the controller with an ohm meter. the path to the brake lights will just be off or on with almost no resistance when on, the path for the brake shoes will vary in resistance depending on how far the lever on the controller moves, if its like mine.

ot need some older info

ericlb

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Paul Janke

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jon f mn

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T.R.K.

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