Electrical help with Prodigy Brake Controller

During a trip this past weekend, my Prodigy brake controller alternated from working correctly to showing an "NC" on the display. I have looked through the forum and the Prodigy troubleshooting info, so I know this usually means that there is a fault that makes the Prodigy think the trailer is not connected, but some of the other behavior I saw makes me think it might not be that easy. Here are all of the symptoms:

Controller flashes NC at random intervals, even when not moving at all - swaps between C and NC with no motion
When controller says NC, trailer lights still work normally (makes me think it is not a trailer grounding problem)
Even with NC showing, the manual brake lever has some effect - hard to quantify, but I'd say it is 50% effective - for example, when stopped with the TV in drive, and the brakes functioning normally, it is easy to hold the TV by pushing the Prodigy manual lever to the left. With NC flashing, the TV will not hold, but there is some braking action provided by the trailer brakes - just not as much as when there is a C showing.
With TV sitting still, Prodigy controller showed two lower bars (indicates Controller is mounted at too low of an angle). The controller is mounted just fine - this symptom makes me think it might be a bad controller

My homework so far says it's probably not the trailer ground, because if it was, the trailer lights would be intermittent - Is this a correct assumption?
So, I am left with:
1. an intermittent short in the trailer braking wires (the blue wire) - although the fact that it comes and goes when the trailer is absolutely stationary makes me think this is less likely)
2. an intermittent connection at the Bargman plug (although the contacts look clean), or
3. A faulty controller

So, my question is - Do any of you electrical geniuses have some suggested troubleshooting steps.

Thanks in advance.

[Wavery]

Originally Posted by TraceyMac

During a trip this past weekend, my Prodigy brake controller alternated from working correctly to showing an "NC" on the display. I have looked through the forum and the Prodigy troubleshooting info, so I know this usually means that there is a fault that makes the Prodigy think the trailer is not connected, but some of the other behavior I saw makes me think it might not be that easy. Here are all of the symptoms:

Controller flashes NC at random intervals, even when not moving at all - swaps between C and NC with no motion
When controller says NC, trailer lights still work normally (makes me think it is not a trailer grounding problem)
Even with NC showing, the manual brake lever has some effect - hard to quantify, but I'd say it is 50% effective - for example, when stopped with the TV in drive, and the brakes functioning normally, it is easy to hold the TV by pushing the Prodigy manual lever to the left. With NC flashing, the TV will not hold, but there is some braking action provided by the trailer brakes - just not as much as when there is a C showing.
With TV sitting still, Prodigy controller showed two lower bars (indicates Controller is mounted at too low of an angle). The controller is mounted just fine - this symptom makes me think it might be a bad controller

My homework so far says it's probably not the trailer ground, because if it was, the trailer lights would be intermittent - Is this a correct assumption?
So, I am left with:
1. an intermittent short in the trailer braking wires (the blue wire) - although the fact that it comes and goes when the trailer is absolutely stationary makes me think this is less likely)
2. an intermittent connection at the Bargman plug (although the contacts look clean), or
3. A faulty controller

So, my question is - Do any of you electrical geniuses have some suggested troubleshooting steps.

Thanks in advance.

The most common cause of something like this is in the harness connector. I would take the TV connector apart and check all of the wires for a stray strand and that all connections are tight. Then I'd do the same with the trailer plug.

I always recommend soldering these bare wire ends before securing them in the connector.

My next area of concern would be the under dash connector to the controller. Did you use a factory pigtail or was the pigtail spliced into the vehicles wiring?

On my TM the connections to the brake drums under the TM at the outer ends of the axle are made with wire nuts. These are prone to corrosion. I suggest cleaning the wires, soldering them and using heat shrink tubing. Check that connection for a high resistance connection or short.

[Wavery]

Originally Posted by rumbleweed

On my TM the connections to the brake drums under the TM at the outer ends of the axle are made with wire nuts. These are prone to corrosion. I suggest cleaning the wires, soldering them and using heat shrink tubing. Check that connection for a high resistance connection or short.

Wire nuts should never be used on a trailer IMO.

These work great:
http://cgi.ebay.com/ebaymotors/200-H...mZ280281070568

I always keep a good selection of them. They have heat-shrink built into the connector and they have a sealer that seals the connector when heated. These are great for trailer and marine applications. No solder needed.

[Frenchy]

I once had one of the brake wires wear through the insulation at one of the plastic wire ties used to hold the wire to the frame. It caused tne NC display to occur but it was continuous. Maybe you have this condition but it does not always make "good" contact with the frame. It was not easy to find this.

One other thought -- if the trailer connector is not fully seated and latched into the jack on the TV, you can get some intermittent indications. This happened to me once when I didn't get the latch fully seated. Brakes might disappear while the running lights worked, for example.

[B_and_D]

Originally Posted by harveyrv

Wire nuts should never be used on a trailer IMO.

These work great:
http://cgi.ebay.com/ebaymotors/200-H...mZ280281070568

I always keep a good selection of them. They have heat-shrink built into the connector and they have a sealer that seals the connector when heated. These are great for trailer and marine applications. No solder needed.

What do you use to heat/shrink the plastic?

"Controller flashes NC at random intervals, even when not moving at all - swaps between C and NC with no motion
When controller says NC, trailer lights still work normally (makes me think it is not a trailer grounding problem)
Even with NC showing, the manual brake lever has some effect - hard to quantify, but I'd say it is 50% effective - for example, when stopped with the TV in drive, and the brakes functioning normally, it is easy to hold the TV by pushing the Prodigy manual lever to the left. With NC flashing, the TV will not hold, but there is some braking action provided by the trailer brakes - just not as much as when there is a C showing.
With TV sitting still, Prodigy controller showed two lower bars (indicates Controller is mounted at too low of an angle). The controller is mounted just fine - this symptom makes me think it might be a bad controller"

I had the EXACT same symptoms during our trip to Yellowstone this past summer. After some preliminary poking around, a mobile trailer repair man hooked up his TV to my trailer with his older Tekonsha controller, and it appeared to be fine. He suggested that it must be my TV. So I went to a Nissan dealer to have my TV connection checked. It was fine. I bought a new controller, hooked it up, and it had the same symptoms. I called Tekonsha, and a seemingly very knowledgable tech support person told me that they were 99% certain that the problem was a grounding issue with the trailer brake wiring. Apparently, the Prodigy is VERY sensitive to these issues, much more so than the older Tekonsha models, so that it can be more "predicitive" of potential failures. I never had any issues with the trailer lights, just the NC indicator and weak trailer brakes.

Armed with all this information, I asked the mobile repairman to come back out. He did (at no cost to me because of his misdiagnosis) and we traced the wiring from the bargeman connector to the battery, from the battery to the wiring bundles behind the fridge, and finally from the bundle to the brake magnet on the street side. When we pulled the hub to check the last little 10 inches of wiring, we found the culprit. There is a little plastic bushing that is supposed to protect the wiring as it passes thorugh the wheel to the brake magnets. Apparently, during the installation (presumably at the factory), the bushing pinched the wire and compromised the sheathing. This eventually caused the bad ground. When we replaced the short section of wire, the NC went away, the brakes functioned properly, and all was well. I have about 3000 miles on the trailer since with repair with no additional problems. About 6 cents worth of wire caused an awful lot of anxiety and misery.

I am not suggesting that your short is in the exact same place (although it could be). But I am suggesting that the problem is a short somewhere in your trailer brake wiring. Give the tech support at Tekonsha a call. They were incredibly helpful. You can also PM me if you would like to get further information about my situation. I am no electrical or mechanical wizard, but I learned an awful lot during this ordeal, and would be happy to share it.

Thanks to all who replied for your excellent suggestions. Given the data provided, I think I will start by looking at the wires to the brakes more closely than I already have, to include removing the wheels and brake drums to examine the wires going into the brake unit. I'll update the post if I ever find the culprit. Thanks

Originally Posted by harveyrv

Wire nuts should never be used on a trailer IMO.

These work great:
http://cgi.ebay.com/ebaymotors/200-H...mZ280281070568

I always keep a good selection of them. They have heat-shrink built into the connector and they have a sealer that seals the connector when heated. These are great for trailer and marine applications. No solder needed.

Interesting conclusion you have reached. My limited experience is different.

I have found that most people can mange to tighten a wire nut properly (aka ScotchLock).

However, many people do not properly crimp a crimp on connector. The only electrical failure I have encountered on my TM was a crimp on connector behind the fridge for the left rear brake light. Someone at the TM factory performed a crimping operation that only lasted three years.

As you likely know, but perhaps some other readers do not, there are two types of crimping tools. One just squeezes it flat while the other sorta pushes a dimple into the center of the connector.

The former is easier to undo. The latter usually will last longer.

I do like the built in heat shrink feature of the connectors that you mentioned.

For a "permanent" splice I still prefer to solder it and then either shrink wrap or electrical tape it. I ahve never had one of my splices fail.