No trailer brakes

dodge man · Aug 30, 2011

It appears my trailer brakes aren't working. I'm almost positive its on the truck side. I have a Teknosa(sp?) Prodigy controller. The truck is a 2002 GMC. When I first hooked everything up it was fine. Then I noticed on rainy days, the controller said "short to battery, no trailer brakes". This happens if the trailer is hooked up or not. I posted about this problem a few months ago and there were several comments about cleaning the plug in at the back.

Tonight was another wet night, so I cleaned the plug in at the back, and also the connector where the wiring plugs into the trailer plug in. This didn't help. I then plugged it into the trailer, and still no go. I noticed when its saying no brakes, that if you hold down the manual lever on the Prodigy, the brake lights on my truck don't come on like they normally would. This happens if its hooked up to the trailer or not hooked up.

I checked the wiring under the dash and where it hooks into the Prodigy, and it looks O.K. I unplugged everthing and plugged it back in with no change.

Any ideas on where to look? My next step will be to start chasing wiring under the truck.

Diamondpilot · Aug 30, 2011

My first guess is its the trucks wiring. You can test the plug with a test light. Some will not test with a volt meter due to no load issue.

If you can find a buddy with a brake controller you can use you could also test it that way.

My guess is its the wiring or the controller. One other thing you can do is every brake controller I have owned disconnects the cruise control via the brake light signal when you slide the manual bar. Try driving with the cruise on and hit the manual lever. It should disconnect the cruise.

As far as chasing wires, start at the plug. Take it fully apart. I have seen many GM plugs full of rust and corrosion after that many years of service.

Hope this gives you a place to start.

Chris

dodge man · Aug 30, 2011

The cruise doesn't work, and hasn't worked since I bought the truck. I probably need to take the plug apart, thats a good place to start. I sprayed some cleaner where the wires go into the plug in, but I didn't pull them and check them.

timswi · Aug 30, 2011

dodge man said:
The cruise doesn't work, and hasn't worked since I bought the truck. I probably need to take the plug apart, thats a good place to start. I sprayed some cleaner where the wires go into the plug in, but I didn't pull them and check them.

The back side of some aftermarket and some factory plugs can fill with corrosion...had this happen on a Reese 7 pin plug once...What a mess that made of the truck wiring..Fortunately, it was an easy fix.

dodge man · Sep 1, 2011

Yesterday was dry and the controller said everthing was O.K. so I hooked up to my trailer. I didn't test drive it but I'm pretty sure everything was working. I just have to figure out where the moisture problem is.

slowzuki · Sep 1, 2011

On dodges there is a common spot the tow harness rubs through on the chassis, there are probably some spots like that on the chev too. Gets wet, shorts out.