Prodigy trailer brake controller?

I have the same truck. Prodigy worked great the first time.

Stud 1 is for 12 volts to the trailer. Stud 2 is used for the brake controller. It must be working or you would not get the "nc" lights.

Do you have a multimeter? Just a cheap one like the $3 ones at Harbor Freight would be adequate.

The first thing I would do is measure the resistance through the brakes on the trailer. Pins 1 to 2 on a 7 pin connector. It should show only

And of course make certain the contacts on the trailer connector are clean to start with. I will assume the truck connector is still clean.

Did you buy the stock GM harness and then pigtail the one from Tekonsha to it? I bought the Tekonsha harness that had both the Prodigy and the GM connector on it. - if you pigtailed I can only recommend checking your connections.

Thanks, I'll try that.

I bought the Prodigy with their GM connector.

David

It should work. Do you have a meter so you can check the resistance of the brake coils? I guess on a 4 wheel trailer the resistance may be about 8 ohms. With a cheap meter you will not get an accurate reading. It may show almost a dead short.

I also expect if you put a low resistance between the brake and ground pins on the truck connector it would look like a trailer attached. A 12 volt light bulb should do the trick.

On my 2003 2500HD the Tekonsha and I had to fight it out with a multimeter. Just check the voltage going to the pins on the back of the truck. Activate the power in manual and you should be o.k. You could also try hooking up a

Didn't GM change the pin out on the controller harness between '02 and '03? Could this be part of the issue?

Checked both, tight and clean.

I have a VOM, but at some point in the past I was testing voltage with the VOM set to resistance, fried that range of values...

Hooked up a 12v bulb between ground and brake pins, no difference. Even jumped directly from ground to brake pin, no difference.

DJ

Yes, there is a technical bulletin covering the change in wiring of the truck side connector. My pigtail is wired per 03-04 specs.

When you say "fight it out", what do you mean?

Did that, no change, even jumped directly from ground to brake pin, no difference...

DJ

Just an update: At this point I've eliminated the trailer altogether. By using a 12v bulb, I've found I get signal from the controller, through the pigtail, through the underdash connection, to a connector under the fuse panel (underhood) but it ain't making it to the rear to the 7-pin connector. I'm losing it somewhere in between. I have a feeling once I get signal to the 7-pin at the rear of the truck the trailer brakes will once again function.

BTW, the trailer is wired standard, works fine on my 85 F250

Thanks.

DJ

Sounds like it's time to take it in to let the dealer have a shot at it unless you have a lot of time to track it down. MR

As Calhoun says it sounds like a problem with the wire harness (Dealer problem).

You don't have a fuse in that VOM?

My next measurement would be a resistance check from the connector for the blue wire on the rear plug to the connector under the dash.

Just to eliminate any issues with the controller, I disconnected the underhood connection and put 12v to the downstream wire , got nothing at the 7-pin.

Okay, start tracing the bundle from the front to the rear to see where any other connections might be, or places open to damage. Hmmm, big pile of spaghetti starting from the front, let's go to the rear.

I'd already pulled apart the 7-pin receptacle, all was well in there, but I neglected to inspect the other end of that pigtail, where the connection to the truck wiring is made.

I pulled it apart. Bingo...

One of the blade connectors on the truck side connector was not pushed all the way into it's slot. I got it in far enough for it to work but it wasn't extended quite as far as the others. It may have not been perfectly aligned and been pushed out when the plug was first pushed into the socket during assembly. I plan to hit the dealership to have them fix it correctly, to my satisfaction. If it were just a light, I'd not worry much, leave it as is but no sense in taking a chance with the brakes going out unexpectedly.

I hooked up truck to trailer and all is right with the world, works as it should.

Thanks to all for the help.

DJ

Thanks for the update. Write a letter to GM giving them hell for their quality control.

I expect that pin that was not setting was the blue brake wire. Since you were getting lights to the controller you knew the fuse in Auxiliary #2 was working. The Auxiliary #1 is used only for 12 volts to the trailer battery.

Ground must have been ok if you trailer lights were working.

Story about my experience with that Stud #1:

I did not buy the controller harness from GM so did not know about the fuse.

I ordered the truck with the camper/5th wheel option. That is just a pigtail just forward of the right rear wheel. I had to drill a hole in the side of the box and hook up a connector to it.

Got it all ready to go and no 12 volts. Looked in the fuse box where I expected it to be hooked up and discovered that plastic plug replacing the fuse for Stud #1.

Then I read the "usage" label which reads: "Auxiliary Power (Single Battery and Diesels Only)/Dual Battery (TP2) Do not install fuse).

Confused me for a bit. I have the Diesel and it comes with dual batteries. Then I realize that the TP2 Dual Battery option is for the gas engines. I had to pay almost $4 at Pep Boys for that unusual fuse.

Since then I have heard that GM harness referred to as "The Glove box harness" and that it includes the missing fuse for Stud #1. Up until a couple years ago it was included in the glove box of all trucks that ordered the heavy duty trailer option. I have heard they still call it "The Glove box harness" but now you have to buy it.

Next project is to put automatic resettable circuit breakers in both those lines. My last truck I used a 40 Amp fuse in Stud #1 and then followed it with a 30 amp breaker. In Stud #2 I put in a 30 Amp fuse and followed it with a 20 Amp breaker. That may be overkill. I have not researched to find out if they make automatic resettable breakers for that model of fuse holder.

Yep.

I was a bit confused by it also but figured about the same as you did so I installed the fuse, hoping it was my controller problem but found it powers the +12V feed to the trailer.

My truck came with the harness, 40A fuse and 7 -> 4 pin adapter plug.

DJ

Hmm, Mine truck is a Sierra. GMC is cheaper than Chevy?? Tomorrow I give it a real test. Pulling my 5th wheel over Berthoud pass (11,300 ft.) on the way to Grand Lake, CO

Does your owners manual read the same as mine? It says to keep the speed below 55 for the first 500 miles and then in addition it says to keep the speed below 50 for the first 500 miles of pulling.

That won't be too hard for me to do. On the way up the hill I just get behind a 18 wheeler that is crawling along at 40 or so. However, going uphill with a load is probably harder than over 50 on the flat. Heading back down the hill I expect speed doesn't make much difference. Well on these trips there are not a lot of roads where I can or want to get over 50 anyway. Even the long stretch from the pass to Winter park has speed limits of 40 or less plus a couple tight switchbacks with limits of 15.

My 02 mentioned not towing for the first 500 miles also. MR

I lost the original posting. I said that the prodigy and I were fighting with a VOM. I meant that I was trying to depress brake pedal with flashlight, read electrical diagram on plug cover and hook up the VOM. I was getting 12.93 volts under full load with ground of VOM attached to truck, and the trailer break on the other line of the VOM. Doing this at about 700pm wanting to pull the first brake controlled trailer with my 2003

The last thing I asked of the service rep at the dealership before I drove away was about break-in. He said "just drive it, put 500 miles on it before towing...", so that's what I did.

You'll love the torque, it may be harder than you think to stay under

2. Have a good trip.

DJ