Trailer Brakes - probable dumb question

[VPayne]

We hooked up a Prodigy Brake Controller to our truck the other day and went to go pick up our travel trailer from storage so we could use it this long weekend. When we plugged the trailer in to the connecter on the truck, the controller doesn't register that there is a trailer connected. The controller works (has power) just won't recognize a trailer, therefore -- no brakes :-( Well, thinking we had a wiring problem, I went and bought one of those harnesses that has one end to plug in to the truck and the other end to the controller -- no splicing. Still same thing. I even bought another controller to see if this was the problem. Still nothing. We checked everything on the trailer which seems to check out fine. So I called the Tekonsha people and they told me to go get a 12 volt test light and put the clamps on the ground terminal in the 7-pin connecter and test the Brake terminal in the connecter(blue wire) and I should get a code indicating a short on the controller if things are working properly which would then point to the trailer. Well, nothing at all happened. No changed codes which indicates something with the truck. When my husband was initially hooking this up (with the splice method), he accidently had the GM harness plugged in as he was attempting to connect some wires and it 'sparked'. Could this have done something like blown some fuse somewhere that isn't obvious? What else can we check? Maybe factory tow package wiring defect? I called Chevy to see if there was a simple way for them to check whether the was a fault in the truck end of things, so we would know whether to focus on trailer or not, but they said that "it could turn into a long troubleshooting thing" and that they didn't have time to do it today. Please, any ideas!! We really wanted to go on vacation tomorrow.
P.S. Turn signals, stop lights etc work on trailer.

[SDWA]

I'm assuming the trailer also has a 7-way connector that fits directly into the truck's connector, and was installed correctly by the trailer manufacturer... If it doesn't (especially if it has a 6-way connector and you're using an adapter) there could be other issues.

To test the brake controller output, you can use a electrical meter (analog or "needle" type works best) at the REAR of the truck by placing the negative lead of the meter on the bottom left blade in the truck-side socket (7 o'clock position) and the positive lead on the bottom right blade (5 o'clock position). Turn the output level all the way up (roll dial towards front of truck on Prodigy) and have someone manually activate the brake controller, if the controller is functioning and wired correctly, you will see +12v on the meter.

BUT!

The "brains" in the Prodigy will only cause a +12v "spike" for about 1 second before the controller senses the improper resistance (i.e. no brake circuit) and cuts the output voltage and displays "nc" on the controller. So whoever's at the back end will have to watch for the needle to "jump" when the controller is activated. If it does, then the controller and wiring to the back is OK, problem is on the trailer side.

On another note, I'm sure the trailer brake output is fused or at least has a circuit breaker, but I can't find such item anywhere on my truck, at least not obviously marked! Anyone else have info on this???

Hope that helps some!

Scott

[ 05-23-2002: Message edited by: SDWA ]</p>

[Searay90]

Check the fuses under the hood, as well as the one's under the dash. If he "sparked" it, then most likely a fuse is burned through. The trailer system is as seperate system, but it does have fuses to protect it from overload and possible fire.

[VPayne]

Should we check EVERY fuse, or just the ones marked 'trailer'? We did already check the ones marked trailer, but those fuses were just for the lighting which works... What fuse would apply for the actual Trailer Braking? Didn't see one of those.
Thanks!

[mdrag]

VPayne,

I would check the 30A Maxi-fuse located at stud #2 in the underhood power center on the DS. If I understand the schematics correctly, this provides the power to the MBEC trailer connector in the cab located near the DS kick panel. The only other fuse I could locate in the trailer wiring schematics is a 10A fuse for the interior/park lights located in the instrument panel fuse block - but I can't see where that would affect the brake controller operation.

Stud #1 is where the 40A Maxi-fuse goes (this 40A fuse should be taped to the brake controller wiring connector/harness if part of the factory option), and provides 12V to the trailer hot lead for powering accesories in the trailer

If your husband got sparks when working on the install, he most likely blew a fuse.

[mdrag]

I found another fuse to check - the 10A CHMSL (center high mounted stop light) - it provides power to the brake switch. The fuse is located in the underhood power center - fuse #16. Good luck.

[VPayne]

Checked fuses that mdrag suggested.... all look good :-( I HATE this stuff! My husband thinks I am 'overreacting' because I don't want to take our trip anyway (ie NO trailer brakes)... I say DUMB especially on long weekend with stop and go holiday traffic.

[pinehill]

Trailer brakes -- Don't leave home without it!!!

[mdrag]

VPayne,

QUOTE:

"Checked fuses that mdrag suggested.... all look good..."

When you say they looked good, does this mean that you checked them with a meter/fuse testor or visually inspected the fuse?

I've had fuses 'look good' visually but check bad with a fuse testor.

[VPayne]

Mdrag... this means I visually inspected them only.

[ndamico]

funny,

i made the same mistake as your husband! Doh! i blew the green 30AMP fuse under the hood. replaced it and everything was fine!

[VPayne]

Ndamico, checked that one and it 'looks' fine. Can anyone tell me for certain if the test light should turn green at the 7-pin connector on truck when the terminal for the blue wire is tested. Either by applying brakes or using the manual knob on the controller? I can get blue light when I probe the blue wire coming directly from the controller, but not at the connector.

[VPayne]

MAYBE FOUND THE PROBLEM!!! Tested all of the terminals at the connector - Right Signal, Left Signal, StopLight by using a 12 volt test light. The test light comes on in each case. When I test the Trailer Brake wire terminal (blue wire in 5:00 position) by applying brake or activating the controller manually -- nothing.... Then my husband came home and digested the info I gave him, so he tested the wire where it FEEDS INTO the connector at the back of the vehicle and IT LIGHTS UP!!! So we must have a faulty connection between the wire and the terminal I would guess. But anyway a nice friend of ours is going to look at it at the Chevy Dealer. Hopefully this is all the problem is and we can still be on our way even though I haven't done ANY shopping or loaded anything into the trailer yet which would have been done yesterday.... since it looked like we weren't going anywhere... Fingers are crossed on this one. smile.gif

[Ranger354]

I had the same problem with my truck a few years back. Sorry I just got to this post this morning.

BTW, how do you like the Drk Carmine Red? It was either that or Forest Green and my wife doesn't care for green.