Ok fellas thanks for all the help in the last wiring thread I made, now I would like some more help! Im installing a brake controller for the electric brakes on my trailer. I have found a wire heading to the back of the truck that I can use for the blue coming from the brake controller, the power and ground is no problem. The question I have is regarding the red wire. In my dump truck I have air brakes, and Im not quite sure where that red wire hooks up too. It was getting dark when I was looking at the brake pedal area, but I didnt notice a place to hook up the wire. I mean theres gotta be a place where the brake pedal engages a switch of some sort to turn on and off the brake lights as needed, but I didnt seem to see it. Anyone hook this type of thing up before? If so, where did ya hook that red wire from the brake controller to? (on an air brake system!) Any help is appreciated!
There is generally an air operated switch that looks kind of like an oil pressure sender. Should have two terminals. Where it is depends on the truck brand/model. Some are close to the treadle valve inside the cab or on the front side of firewall in same general area. Our Sterling has it behind the drivers seat. There will also be a low air sender that looks almost the same close by. On the Sterling they look exactly the same and are within 3 inches of each other, but they were labeled with function.
This is how it looks on my Freightliner FL70. It's on the driver side in front of the firewall under the hood. The brown wire on the bottom is the "red'' wire going to the brake. I did not have any red wire so that's the way i did it. You may also have to get a (3 to 2) wire kit like I did. Works great now and I can also pull an airbrake trailer!
Ok thanks for the replies. I have a couple of those air switches right by the brake assembley (if im still having problems later today I will post pics). On the posts of them though, the one post is grounded to the cab, then grounded to the other switch. The other posts are just connected to one another and then nothing. I am assuming they arent hooked up to anything(did alot of testing yesterday) so today i am gonna try hooking power to one, and test it to see if the brake actuates it. If so I am in the money! Do you know where the other wires that go to that switch of yours timark80? like one side should be a power, then the other side goes to your brake lights/brake controller? I know about those grounded switches too (forget the proper term) and I dont think its one of those. I tested for that last night.
Ok, posting back with results, good ones! First off I feel kinda dumb (isnt that what forums are all about?!). I was testing the two switches right near the brake pedal/valve. Here the whole time I was just about laying on the one that I needed to find! What i did was trace the hoses (in the daytime when there was light out) found that air switch located at the drivers side "kick panel" (where it would be anyways). Tested it, hooked up my wire, brake controller works great! Zip tied up all the loose hanging wires, and that part is good to go! Now I just have to finish the plug on the trailer to match it up to the truck and I am good to go. Thanks for your guys's help, specially with my newbie question, that in the end, the problem was my head was up my @ss! haha.