1985 trailer brake controller

[BrianX128]

I'm lost. My 1985 f350 has this type of plug on the back and this type of internal controller inside with a brake line from the master cylinder running right into it [new to me]

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So when I first went to test it tonight only the running lights and left and right brake light / turn signals worked right. The little led on the controller never would come on. There are three wires going to the controller in the back electric taped into just two, red and brown. I spliced into the red which was dead even with the key on or running and gave it power when the key is on and that got me the trailer brake portion of the diagram to light up when the brakes are pressed as well as the light on the controller to turn on when the brakes are pressed.

I still have no reverse lights which I really don't care about but no matter what I do the aux 12v / charging portion never turns on.

Do I even need that 12v aux one to haul a car hauler trailer? Will the brakes still work because the electric brake portion works?

If anyone is familiar with this controller perhaps the brown wire is also for power? It doesnt seem to respond to anything with a test light. I could just cheat and run a positive wire back to the hitch from the fusebox but if I dont need it for car trailers I'm not gonna bother as long as I have brakes and brake lights and turn signals.

Also the po provided me with all these disconnected connectors under the hood. Good times. Any help and advice appreciated, my 7.3 the controller always just worked.

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[laserjock]

Those controllers were standard issue back in the day. There should be a big resistor under the hood to adjust.

You don’t technically need the charge wire for the car hauler but it should be connected to the breakaway box battery to charge it. As long as it’s charged it’s fine.

Edit:

I seem to remember the power wire for my brake controller under the hood was red. It came from a fusible link I believe so check your link wires. May be why you have no power.

 

[BrianX128]

So I spliced into the brown wire going into the back of the brake controller and now the light on it comes on when the key is turned on. Now I'm wondering if I need to unplug the red wire? Before splicing in the brown wire, when I pressed the brakes down the led would come on on the controller after it was pressed so far and the electric brake controller terminal would light up when this happened but was that just the controller turning "on" when the brakes were pressed so far?

Dad's truck with an electronic controller (a u haul controller) when the truck is on the 12v power is always on but so is the terminal for the electronic brakes without even pressing the brake and it gets brighter as you press them down.

 

[nostrokes]

Honestly you're best bet is to replace it with a electronic one. Dad had those older ones and they never really worked great and you can't adjust them on the fly so wheither loaded or not it always applies the same brake to the trailer.

 

[saburai]

Honestly you're best bet is to replace it with a electronic one. Dad had those older ones and they never really worked great and you can't adjust them on the fly so wheither loaded or not it always applies the same brake to the trailer.

Excellent advice!

 

[BrianX128]

Only problem short term is I gotta tow this tomorrow or Thursday. Only on 35mph road 7 miles on mostly flat ground. I just need it functional enough for this and my 7.3 which works fine is currently torn down for the new smf and clutch so it's not an option.

 

[laserjock]

Brian the big plug in your first post looks like a relay socket. Probably for your charge circuit. You really don’t need it for a car hauler if the battery is charged for the breakaway. If it’s not charged then the breakaway won’t work. Your call there on necessity.

Those controllers work okay when adjusted. Hopefully an old timer will help me out but I think the load resistor under the hood is the coarse adjustment and the knob rotated for fine adjustment. My dad had one identical to that in his 83 but I don’t remember much more about them. I don’t know if the output is proportional to the pedal pressure or not.

Remember you can activate manually with the lever on the front so you can hook it up and actuate it to try it.

 

[nostrokes]

Ok didn't know you're on a time crunch. Like lazerkock said you can hook it up and test it. Either hold the oh crap handle over to the left and try to inch forward or take a short drive and press the brakes.

IMHA going 7 miles on a mostly flat road I wouldn't even try to get it working, unless I was hauling over 10,000 pounds. I've always had to borrow my brother in laws trailer and his brakes never worked, just start slowing down sooner and coast as much as you can let the tranny do most of the "braking".

 

[BrianX128]

Ok yeah I can test it in my driveway and see if it works at all and how touchy it is. I'm thinking the thing is supposed to be on all of the time as far as the led on it and not just when the brakes are pressed halfway down.

If the previous owner didn't make such a giant mess of wiring under the dash I might have some clue as to what is going on here. It's almost like the thing was dealer installed originally the way the brake lights / turn signals are wired into everything properly and it's like he decided to wire something else into the same wires under the dash and just butchered everything.

 

[BrianX128]

Weirdest part is there's 3 wires coming out of the controller but two of them are electric taped / spliced together out to just 1 wire which wouldn't make any sense. The original wiring diagram had 3 wires for these Kelsey Hayes units and the three wires coming out were 12v to the controller, a wire to go to the cold side of the brake switch so it knew when it was pressed down, and a wire to the hitch for the electric switching of the trailer brakes.

There's 0 combo that would be useful if you wired two of those together unless I'm missing something.

 

[chillman88]

Sounds like someone didn't know what they were doing originally.

@laserjock is right. Coarse adjustment is the "board with springs" usually under the hood if it's even installed. Fine tuning is either a dial or turning the knob on the controller itself.

Mine has 1 power in, one brake control out, and 1 brake light SIGNAL that's supposed to be wired to engage the brake LIGHTS when you manually actuate the controller (in case of emergency).

You need to add load to the circuit to test it. I cobbed an old headlight to the brake wire so that I could tell it was VARYING THE VOLTAGE by the light getting dimmer or brighter. A DVM won't usually pick up on it with no load on the circuit. A test light might not be enough load but I'm not sure.

EDIT: Honestly if it was me I'd just haul it like it is. I've hauled further with no brakes on my trailer, not that I'll admit to it.... again. You should be fine if you use your head, just be careful. We can get this figured out, but I know what it's like being in a bind!

 

[BrianX128]

I have tonight when I get home from work to figure it out. Figures this comes up during the 2 week segment over 16 weeks at work where I'm not 630am-3pm and I'm here until 630 doing next to nothing looking at old wiring diagrams for this. I know that "a" wire is hooked from the controller to the back receiver because when I had it running a hot wire to the red wire of the controller last night and left everything else as is, when I pressed the brakes down the led on the controller lit up and the terminal for the electronic brakes on the receiver would have power. I think that circuit and the main power are spliced into one wire wrong from the previous owner. I think the red wire is plugged in correctly to the brakes, or the unit wouldn't have came on when I pressed the brakes down thinking the red wire was for power.

So, I think I need to:
1. unsplice my red wire from the fuse box.
2. unsplice the black and blue wires so they are not together and leave the blue from controller hooked up to whatever the hell exits that splicing
3. use the wire coming from the fusebox that is powered by the key on to the leftover wire coming from the controller which hopefully is black and is power into it
4. run a long wire from the same key on fuse under the dash the whole way along the frame back to the receiver and splice it into the 12v charging port of the receiver as tracing it backwards is going to be 100% impossible at this point. although it will probably blow the 30amp fuse charging a battery on the trailer and mess up the entire project. we'll call this optional. haha
5. splice a wire from the reverse light switch which i already have for my anti-tailgating light button in the dash back to the reverse port on the receiver as tracing it is pointless as well.

I have like two hours to do all of this tonight and it's going to rain. Neat.

 

[laserjock]

I wouldn’t screw with reverse lights. Most trailers don’t have them anyway.

If the lights work [emoji1303]

If the brakes work [emoji1303][emoji1303]


Given what you said about the trip if I were in your shoes, I’d probably not sweat it a lot but I will never tell anyone to neglect safety.

 

[chillman88]

In case this helps. I went out and snapped a picture of the instructions of the NOS controller I bought for my truck.

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I'm sure it'll be a little late, but I can get better pics tomorrow if needed.

 

[BrianX128]

I want to kill the previous owner. Not really but the stupidity I'm running into is amazing. I don't have clean wiring I'll be the first to admit it but I at least follow the wiring schematics and install things that work.

I have a video I'm uploading that you guys won't believe.

Anyways I made some progress. I found that the red wire for the brake lights if you push the controller is unhooked and taped up- fine just leaving it that way. The black wire that powers the controller is dead and I can't trace it but the fusible link is dead because when you spin the brake controller knob the whole way to one side if you turn hard it sparks so someone probably did that and shorted it out. The wire going to the resistor under the hood is hooked to the clock in the dash instead and only turns the clock on if you push the brake controller to the left now that it has power.

No I'm not drunk. That's what it does.

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See?

So I traced the clock and hooked it up correctly no more 1888.

And routed the blue wire to the resistor which is thankfully routed back to the electric brake portion of the hookup on the hitch. And when I press the brakes or slide the slider it lights a test light on that terminal! Wahoo.

It also only barely lights up a truck headlight from that terminal no matter how much you push on the brakes and never varies in intensity. Just a dim fade.

The resistor under the hood is... rusty... wondering if I should just hook those two wires together? Sure cant adjust it. On dads truck with the u haul controller the light only lights up dim when pressing the brakes as well but it sure gets bright with the slider...