Visit our Popular Forums

59toaster · 03-13-2003, 07:27 AM

One of my trucks has a Old KH hydraulic brake control. I got to looking at how this thing is wired and it confused me as to WHY they would do it this way.I have a resistor inline with it also.

It apears the main power come FROM the trailer (or possibly the trailer charge wire), through the adjustable resitor under the hood then through the brake controler back to the trailer (or it could be the oposite route).
Why would you feed off the trailer for brake electric power? I also have the main charge lead backe there as well. The truck side plug was not on it so I guess it's possible that the feed to the trailer was tagged for the feed to the controler at the plug. Just seems odd to me that they would run all that extra wire when right on the fire wall is a main junction block off the battery.

Silvertwinkie · 03-13-2003, 07:41 AM

WOW! What a blast from the past.......

We had one of those units (70's and mid 80s), but to the best of my memory, ours didn't use any power from the trailer. It was all fed from the tow vehicle, but remember I'm pulling memories from almost 2 decades ago.

Regards,

Eric

59toaster · 03-13-2003, 07:59 AM

Heheh Yeah I have two of these. One was on my 75 Jimmy when I bought it and the other was on a 77 Blazer I stripped some parts off and is now in a box. I understand they were good controlers but a pain to hook up because of the Hydraulic connection. I have had to bleed the one in my 75 when I did some major brake upgrades (now has four wheel disc). Royal pain to bleed. It appears to work and I'm concidering occasionaly pulling the A/S. I also have a little cargo trailer (3500lb MAX with load) that I pull a lot and it doesn't have brakes. I have only felt they were needed a couple times but I'm concidering them more and more.

Silvertwinkie · 03-13-2003, 08:26 AM

You're right, they were and still are great units. Ours worked in our '77 Ford LTD wagon and then was tranferred to our '85 3/4 454 Suburban. Never had an ounce of problems with it--at all--ever.

But you're right, brake jobs and installing were unique.

With all the technology that has come since the old K/H systems, I didn't think anyone else remembered let alone still used those old boxes. I miss the big black knob "whammy bar" slide that it had when you pressed the brakes.

Tell you what, those K/H boxes worked better than most (not all) of the electronic crap on the market today.

Eric

john hd · 03-13-2003, 06:01 PM

eric

my manual states that with the kh controller, the black is source from tow vehicle battery (no fuse!).

red to trailer stop lamps.

blue to trailer brakes.

john

59toaster · 03-13-2003, 06:32 PM

Thanks John. I don't think the red is even hooked up.
Black to battery is strange for 12v. Does this vary the ground and not the positive?

john hd · 03-13-2003, 07:04 PM

eric

yes it seems strange, but i have learned over the years that colors are not important.

if you work on a piece of epuipment you may notice a "theme" in the color coding. most companys use whatever color they want for + or - , hot or neutral.

my brake controller had completly different colors than the factory supplied harness that came with my silverado.

it would be nice for everyone to use standard colors for wiring, but they won't, never have and never will!

case in point, high voltage. you would think people would really care about marking stuff correctly if life and limb were on the line.
they don't!

blue yellow red = 120/208

brown orange yellow = 277/480

would i risk my right arm that it is marked correctly?

NO!

bottom line is, check it with a volt/ohmmeter if you have a doubt.

ignore the colors.

john

Silvertwinkie · 03-13-2003, 07:05 PM

Quote:

Originally posted by john hd
eric

my manual states that with the kh controller, the black is source from tow vehicle battery (no fuse!).

red to trailer stop lamps.

blue to trailer brakes.

john

Glad I didn't wire it up. I would have for sure fried something out had I tried!

Fuse? We don't need no stinkn' fuse!

Eric

john hd · 03-13-2003, 07:07 PM

eric

it varies the amount of current flowing to the trailer in the POSITIVE wire no matter the color.

i kinda got off track about your color question.

john

59toaster · 03-13-2003, 07:37 PM

Well the paper work for the A/S was withing arms reach and I Remebered seeing something for K/H in there. Sure enough I found a booklet from K/H dated 1957 LOL. On the cover is the SN# of the camper. Looks to be original to the camper for not only the controler but the brakes on the trailer. Has full detains on adjustment of everything. Allthough the contol in the ilistrations are not the same as the units I have they are the same color codes. It alos lists as 6V so I wonder if my brake system is a 6v system or if it has been updated at some point. Found no other brake(as in the parts on the A/S) indicating they were ever changed. They worked fine when hooked to the Van my Father-in-law used last. Different controler that I do have the paperwork on but the van is now in CT with the controler.
So this leaves me with another mystery and I need to figure out if I have 12v or 6v brakes. If they are 6v then they may have run them in series to get them to operate with the 12v supply.