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  1. #1
    Setting Up Camp
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    Need help - intermittent connection between truck and 351M

    I really try to research and come up with a solution on my own but this one is a challenge.

    Okay, here's the story.

    Back in August I forgot to pull the cable from the trailer to the truck when unhitching. Well, it pulled the junction box in the kingpin off and put a strain on the cable. I looked for anything broken; pins, connectors, etc.. I looked for frayed or cut insulation. Everything looked good. When I hooked up to leave everything worked. And it has worked until now. Coming into the campground south of Atlanta, about 10 miles out, the truck couldn't sense the trailer and told me it was not connected. I tried the brake controller inside the truck and the display came up grayed out. No brakes. The running lights were still on as I could see them. Suddenly the truck could sense the trailer and everything worked. The connection went in and out until I reached the campground. This was on the 23rd.

    Yesterday I connected the truck to troubleshoot and the truck would not sense the trailer. I pulled the junction box off to get it where I could work on it and started another visual check for loose connections, frayed or cut wires, loose grounds. Nothing. Nothing I touched or wiggled made a difference. I searched on the web and found the wiring for the brake control and made sure I double checked that specifically. The connection is two blue wires, a black and an orange. I wanted to take apart the 7 pin plug on the trailer cable to see if a wire had come loose from a pin but it's a sealed connection. I called the cable manufacturer to learn this. I was going to start taking apart connections in the junction box to check continuity from the plug to the box but rain was coming and I didn't want to rush so I put everything back together. I decided to plug it in for one last check and it was working. I tried moving the plug and all the connections in the junction box and could not get it to fail. I'm stumped.

    Things I have done include; as mentioned, looking for frayed, cut or broken insulation on the wires, looking for loose connections or wire crimps, checking any ground I could find, I even crawled under the trailer to make sure the wiring to the electric brakes wasn't damaged in any way. I ran the truck through a test to make sure the truck wasn't the issue.
    I haven't been able to follow the wiring once it leaves the kingpin and enters the trailer. I believe these are just straight runs to the lights and brakes but I'm not sure.

    Got any ideas?
    Thanks,Wayne

    PS. I'm adding this comment with all respect to the members of this forum. If this thread brings to mind a question on a related but different topic please create a new post. I really need to get this problem fixed and scrolling through unrelated comments is time consuming. Thank you.
    2019 Grand Design Momentum 351M
    2018 Chevrolet Silverado 3500HD LTZ DRW CC 8 ft bed, B&W Companion hitch
    2018 Harley Davidson Roadglide Ultra
    2019 KTM 790 Adventure

  2. #2
    Paid my dues 😁 FT4NOW's Avatar
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    Have you tried troubleshooting the truck end of the connection? Maybe there is a loose wire somewhere on the truck.

    If you have a friend or neighbor with a trailer, try plugging their trailer in your truck and see if it recognizes it. Also see if they can plug their truck into your trailer and that will at least isolate if the problem is on your truck or the trailer.

    Sent from my SM-G950U using Tapatalk
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  3. #3
    Fireside Member thunder550's Avatar
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    Have you cleaned the contacts on the truck and trailer connectors? Could be as simple as a thin layer of corrosion on the metal contacts on either side. The intermittent nature, as well as lights still working when the brake controller isn't makes me think it's something like this.

    I had a 2011 Silverado with the factory brake controller awhile back and it was really sensitive to corroded contacts. Had same symptoms as you...lights worked, but the truck said no trailer was detected. Cleaned up the contacts and no more problems. Of course I was in Colorado at the time so dealing with snow and mag chloride on the roads, but it's still worth checking if you haven't already.
    Last edited by thunder550; 10-25-2020 at 08:53 AM.
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  4. #4
    Setting Up Camp
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    Good idea. Thanks. I did follow instructions in the truck manual for checking the trucks function. It indicated the truck was fine. I also plugged into the bumper 7 pin socket with the same results. I'll see if I can find someone here willing to connect. I have two more travel days before I get to a location where I can use a friend's truck.
    2019 Grand Design Momentum 351M
    2018 Chevrolet Silverado 3500HD LTZ DRW CC 8 ft bed, B&W Companion hitch
    2018 Harley Davidson Roadglide Ultra
    2019 KTM 790 Adventure

  5. #5
    Setting Up Camp
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    Quote Originally Posted by thunder550 View Post
    Have you cleaned the contacts on the truck and trailer connectors? Could be as simple as a thin layer of corrosion on the metal contacts on either side. The intermittent nature, as well as lights still working when the brake controller isn't makes me think it's something like this.

    I had a 2011 Silverado with the factory brake controller awhile back and it was really sensitive to corroded contacts. Had same symptoms as you...lights worked, but the truck said no trailer was detected. Cleaned up the contacts and no more problems. Of course I was in Colorado at the time so dealing with snow and mag chloride on the roads, but it's still worth checking if you haven't already.
    I saw that someone suggested a cleaner in another post. I'll see if I can find it and give it a try. Always good to try the easiest fix first. Thanks!
    2019 Grand Design Momentum 351M
    2018 Chevrolet Silverado 3500HD LTZ DRW CC 8 ft bed, B&W Companion hitch
    2018 Harley Davidson Roadglide Ultra
    2019 KTM 790 Adventure

  6. #6
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    Do you have a meter ohm/volt type. If so have the plug at the junction box and test the wiring between the plug and there. While I dont have a problem. I got this to clean things up. Several folks have used it (where I got the idea) https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
    2018 Reflection 150 Series 220RK 5th wheel with 6K axle upgrade. B&W 25K OEM Companion, Steadyfast system, 2022 F350 SRW 6.7 King Ranch 8' bed, Trailer reverse lights, rear spare tire holder, storage tube, sumo springs, Victron MultiPlus 12/120/3000, and Solar

  7. #7
    Setting Up Camp
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    Quote Originally Posted by powerscol View Post
    Do you have a meter ohm/volt type. If so have the plug at the junction box and test the wiring between the plug and there. While I dont have a problem. I got this to clean things up. Several folks have used it (where I got the idea) https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
    I do have a meter. Testing between the plug and junction box was next on the list but at the end of yesterday it was working and I don't seem to be able to break it again. I'll connect again tomorrow and see if it's working or not. If not I'll test the cable. Either way I will order the cable in the link you provided. It's so much better than the current set up. The current connections are a rats nest of crimped connections.

    Thanks
    2019 Grand Design Momentum 351M
    2018 Chevrolet Silverado 3500HD LTZ DRW CC 8 ft bed, B&W Companion hitch
    2018 Harley Davidson Roadglide Ultra
    2019 KTM 790 Adventure

  8. #8
    Long Hauler geotex1's Avatar
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    Do make sure you're not chasing the ghost in the wrong place. I hear you that you gave the junction box a good yank and the umbilical stretched taunt. Seems like you have already been going through these. However, your issue could be a bad connection at one of the magnets. Check back at the axles for solid, clean, and water-tight connections at each backing plate.
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  9. #9
    Setting Up Camp
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    Quote Originally Posted by geotex1 View Post
    Do make sure you're not chasing the ghost in the wrong place. I hear you that you gave the junction box a good yank and the umbilical stretched taunt. Seems like you have already been going through these. However, your issue could be a bad connection at one of the magnets. Check back at the axles for solid, clean, and water-tight connections at each backing plate.
    Good point. I'll search this to make sure I understand what I might be looking for. I did climb under the trailer and looked for something obvious. All looked good. With the junction box connections working since my error in August I may need to look elsewhere.

    Thanks
    2019 Grand Design Momentum 351M
    2018 Chevrolet Silverado 3500HD LTZ DRW CC 8 ft bed, B&W Companion hitch
    2018 Harley Davidson Roadglide Ultra
    2019 KTM 790 Adventure

  10. #10
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    Quote Originally Posted by NFurno View Post
    Good point. I'll search this to make sure I understand what I might be looking for. I did climb under the trailer and looked for something obvious. All looked good. With the junction box connections working since my error in August I may need to look elsewhere.

    Thanks
    My bet is inside the sealed plug you stretched a wire and it is making intermittent contact. Also looke for bent pins in the truck plug. When testing twist the plug around. You can always just by a new plug and wire it up.
    2018 Reflection 150 Series 220RK 5th wheel with 6K axle upgrade. B&W 25K OEM Companion, Steadyfast system, 2022 F350 SRW 6.7 King Ranch 8' bed, Trailer reverse lights, rear spare tire holder, storage tube, sumo springs, Victron MultiPlus 12/120/3000, and Solar

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