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TriCityLawnCareLLC
04-20-2011, 07:40 PM
I bought a nice Big Tex trailer used off of craigslist, it's in great shape but the only issue i am having is with the breaks. I have a 05 GMC sierra 4x4, I bought a reese control box, plugged it into the factory pigtail (used the correct wire diagram to match the correct wires) plugged her all in and it gives me the signal that the controller is plugged in correctly but says that the trailer is not connects?? I'm not sure where to start to look. I've checked to see if there are any fuses for trailer brakes, only found one fuse under that dask and it just says brakes. So any insight from you guys would be great. :confused::usflag:

TriCityLawnCareLLC
04-20-2011, 07:41 PM
trailer is not connected to vehicle**

knox gsl
04-20-2011, 07:47 PM
Have you checked the plug on the trailer with a ohm meter to see if there is a completed circuit for the brake magnets? This is the first place to start.

TriCityLawnCareLLC
04-20-2011, 07:55 PM
I haven't, I'll try that. Thanks

GMLC
04-20-2011, 07:56 PM
In the fuse block under the hood is a spot for a maxi fuse that powers the trailer brakes. That fuse usually needs to be put in. Also sometimes under the same fuse block there is a power wire that needs to be connected together to allow the power from the fuse block to go back to the trailer.

cms289
04-22-2011, 05:37 PM
The fuse in the A spot on the fuse block under the hood is not for trailer brakes, it is for the 12v power. Max amps is 40, I have 30s in all my gmc's. For the brakes will need a controller, and I say spend the 10 dollars for the made connector cable. It will makes sure it is correctly done. Most controllers will tell you if you have it connected correctly and have the correct load. In addition, you can check the voltage at the actual brakes. Most trailer places have a plug they can plug into the 7 prong plug on the truck and you can see if everything is working correctly. You can buy, but my supplier let me use it in the parking lot on an older truck I put everything in ( not like the gmc's that have factory stuff), it made it easy to see that all was fine to that point. If it is not working then you can work on the trailer and trouble shoot.

It can be hard to do the whole thing new as you have too many things to check if not working correctly. Start on the truck, once you know that it is right, you can see if the trailer is working right.

www.brakecontroller.com They have like 8 sites you can link too, everything you can want for trailers, they are in Dallas Texas, but they ship cheap. I have used them for years and they have everything in stock and are the cheapest place I have found.

I have 2 2005 gmc's one 1500 z71 (wifes) and a 1500HD 4x4 (mine). They are good trucks but the 1500 trans went at 80k miles, the hd has never had an issue, best overall non diesel towing truck I have ever had. Have a f250 with the 460 and it will out tow it but not as nice when not towing.

GMLC
04-22-2011, 08:12 PM
Its labeled as post #1 in the under hood fuse block and is able to hold a 50 amp maxi fuse. This 50 amp maxi fuse will be taped to the GM trailer brake controller harness. Gm trucks are pre wired to run this 50 amp power through the trailer brake controller and all the way to the trailer conector out back specificly for trailer brakes. And like I said double check under the under hood fuse block to make sure this power wire is conected. The factory leaves it unpluged. If your using GM harnesses you don't need to do any wiring on your own!
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ALC-GregH
04-23-2011, 10:39 AM
Its labeled as post #1 in the under hood fuse block and is able to hold a 50 amp maxi fuse. This 50 amp maxi fuse will be taped to the GM trailer brake controller harness. Gm trucks are pre wired to run this 50 amp power through the trailer brake controller and all the way to the trailer conector out back specificly for trailer brakes. And like I said double check under the under hood fuse block to make sure this power wire is conected. The factory leaves it unpluged. If your using GM harnesses you don't need to do any wiring on your own!
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This correct. The wires you'll find should be a blue and red wire. Blue being the wire for the electric brakes and the red being for a hot lead to power accessories on the trailer.

I've hard wires TONS of trucks with brake controllers to the point I could just about do it blindfolded!

cms289
04-26-2011, 10:21 AM
Talk to a dealer on the 50 amp. I read that it was 50 amp too (I got a wire but no fuse with either of my trucks, I understand some have a fuse in the bag with the wire for the controller (plug on one end for the truck and open wire on the other to wire it), but my guy at the dealership said max 40 and he would not run more than 30. He said they had a few of meltdowns that destroyed the elect system. He said it was a trailer that had a large draw, (winch, lights, compressor, ect). I have a toy and trailer for it, but it has a gen so I do not need to draw from the truck for the trailer. I can see no reason for a non race/live in needing more than 20 amps, and better safe than sorry. I would think short term 50 amp would be fine, but if something shorted and drew 50 amp for a long time it might be an issue. Gmlc is right, 1 not A. Nice catch.

good luck getting it all working