Trailer Brake Controller

jwstewar

Member
You guys might remember that Monica and I bought a new Suburban back just before Christmas. It is awesome BTW, we really like it. Any way, I ordered a Tekonsha P3 brake controller for it. Would like to be able to tow my new trailer and the camper with it should we need to. I installed it last night. With the newer GMs they don't come with the plug-in harness like they used to. Now they just leave blunt wires under the dash and you just either solder or use butt-joint connectors. I don't like soldering under a dash, so I just used butt-connectors.

The GM wires are labeled 12v, Aux, Ground, and CHMSL (brake light switch). The 12v and Aux hooked up OK. When I was doing the ground or brake, I must have dropped one and grabbed the other by accident. The controller told me I was getting a short. I realized my mistake and switched the wires. The controller will tell you the voltages you are getting. On my brake light switch I get a constant .4 volts. Once I push on the brake pedal (with engine running, off don't get anything) it drops to .27. I verified this with my volt meter with the wire disconnect from the controller. I would have thought I would have gotten 12v. Is it just me or does something not seem right? I have not towed the trailer yet with it to see if it is working or not. Otherwise, it seems to be working. BTW, the CHMSL on the Suburban is working, I thought maybe I had blown a fuse but that isn't the case.

It knows when the trailer is connected or not and also knows the current draw of the trailer brakes. Right now I have it set for max 6 volts and it is using 5.5 amps when I manually apply the brakes fully. I can up the max volts it can apply to the trailer. 6 is where they recommend to start the max voltage and adjust it from there. It can go up to 12.8 volts.
 

bczoom

New member
I'd test again with the trailer attached. If I recall correctly, the P3 is an interial (sp?) based system. Since the truck is sitting there (and there's no trailer attached), there's nothing for it to do.
 

jwstewar

Member
I put the multi meter on the actual CHMSL wire from GM and that is the voltage I was getting. I took the controller out of the picture completely.
 

bczoom

New member
Unfortunately, you may have an issue... with the truck.

I need to check with my friend who just bought a new Silverado but as I recall, here's what he found out. I'll e-mail him for the details to see if they apply to your situation.

The new Chevy trucks (and therefore, probably the Suburban) are NOT really wired for a brake controller.

Luckily, as part of the purchase, he included that they move his brake controller from the old truck to the new. Well, the mechanics crawled in to do so and the wiring came up short (lack of wires as I recall). Several hours of labor later, they finally got it properly working.

Do a google search on the topic.
Here's an article I found that may help.
http://www.justanswer.com/questions/yp0l-connect-tlr-brake-controller-2007
 

jwstewar

Member
Thanks Brian. That is the same directions I used mine came from Tekonsha though. I still need to add the 40 amp fuse though to charge the battery on the trailer. Believe it or not, it was also in the owners manual.
 

jwstewar

Member
I stopped and bought the 40a fuse last night. Guess what, GM had already put it in. So now I have a spare.:yahoo:

I think I also found the problem with my brake signal voltage:ermm: or more appropriately - Monica did. She just called me and asked why the he!! wasn't the cruise control working. Guess I figured out what circuit they piggy backed that off of didn't I. I'm assuming I've just blown a fuse. I'll replace it tonight and see what happens.
 

bczoom

New member
Hmmm, maybe that 40A fuse has an immediate need!

Let's hope it's the fuse. Do they want you to up the amps on that one?
 

jwstewar

Member
None of the documentation has said anything about it, so I'm assuming it was because of my little screw up and just replace it with a 10a (I'm assuming that is the size) when I get home and see what happens.
 

jwstewar

Member
Woohoo!!! I picked up a variety pack of fuses on the way home. Got home #43 was blown replaced it. As soon as I started the engine and hit the brakes I had 14.29 volts coming to the controller. BTW, the brake lights don't come on if the engine isn't running and you press the brake pedal. Just thought that was neat. Anyway, just got back from picking up a horse trailer with it. It is 16' steel (fairly heavy) trailer and the contoller worked great. Once the brakes on the trailer got cleaned up. It is been sitting all winter so they didn't want to work at first. Between that and it grounds through the ball (I hate that), they didn't work at first. After going down his driveway, all was well though.:clap:
 

jwstewar

Member
Mine on my new trailer and camper are good. The camper has a Group 27 Deep Cycle that stays charged via ther inverter. And the battery on my trailer is good - well because it is new and I left it plugged into the truck for awhile. Now this horse trailer on the other hand needs a little TLC. It actually needs a breakaway switch. I would install that as payment for borrowing, but not sure where that would lead me to next that needed repair. Wouldn't mind paying a little to fix it since I've borrowed it a few times but don't want to get into huge $$$ either if you know what I mean.
 

bczoom

New member
The horse trailer is borrowed? A breakaway switch should be about $10. I'd probably do it. As a loaner myself, I don't expect anything back but it is nice when someone (loanee) sees something wrong and fixes it. I have no expectations of getting something fixed on each loan. A person doing it once provides their credibility in my book.
 

jwstewar

Member
Yep, the horse trailer is borrowed from my cousin to help move my in-laws. Another long story, you can see it on FF. But I've used this trailer a few times to move stuff. Monica and I originally moved to our house with this trailer and then I used it last year to go the furniture that we had bought for the new house.

If you'll read the story on FF, this will make sense. My F-I-L wanted us to leave the trailer at his house today and he would bring it back. I wouldn't do that. He doesn't have much experience pulling trailers and his Dodge 2500 doesn't have a brake controller. With him not having experience pulling a bigger trailer, there is no way in hell I'm letting him pull a trailer I've borrowed and am responsible for. Besides I would feel bad if he/someone got hurt/killed in a wreck because I knew better. He made me mad a couple of years ago, he borrowed a trailer so he could use my tractor. I asked if he had a brake controller and he lied and said yes.:cuss: Made mad to the point, he won't tow anything of mine any more. If something needs done, I'll do it myself now that I have my new trailer.
 
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