Intermittent Trailer Disconnect

[KBinAZ]

Hi, I could use some help. We have out last leg of our trip tomorrow from SLC to PHX and my Truck does not recognize the trailer.

Our trailer sat for 5 days at Yellowstone. connected this morning, no problem. Then during the drive the truck would intermittently un-recognize, then re-recognize the trailer. This steadily got work until it no longer recognized the trailer.

All connections seem to ok. Battery connectors, trailer connector to truck. Last time I checked power in the trailer was ok. I need to go back and check again.

If it was a fuse or something I would have expected it to just stop. maybe something moving is causing a short?

2016 x17z
2018 Toyota tundra
I have installed the renogy solar with the BT connector.

Funny thing I stopped a rest area to check...and of course all was good. And a guy pulled up next to me and was having the same issue...totally different equipment.

Any thoughts?

[KBinAZ]

Quick update. I just check all I know to check. The truck is still not recognizing the trailer on the dashboard. But I do have lights! When I turn on the headlights the trailer tail lights and side-markers turn on. This is good. I was worried about driving without those. I will check all, brake lights and turn signals.

Seems I still do not have trailer brakes. If needed I will just take it easy and use lower gears and flashers on the mountain downhills.

[craigav]

Be sure to use tow\haul mode during any downhill runs, that mode will allow for better engine braking. It sounds to me that you don't have a good connection for the brakes, I would try cleaning the trailer plug and see if that helps. ~CA

[KBinAZ]

Thanks. I will try cleaning that. I always use tow/haul mode...the engine braking is noticeable.

[ttavasc]

Had this happen shortly after I bought the '19 F-250. The resolution for me was to find every connector under the bed of the truck related to the trailer plug wiring, open it up and fill it with dielectric grease. Also filled the 7-pin connector. No further problem in the ~2 years since I did that. Apparently moisture can get into the connections and causes the random disconnect events.

[Dkastner]

We had a similar issue when we purchased our Jayco trailer with no signal at the brake controller.

The service techs checked the connector on the trailer and would actually apply the brake on the driver's side wheel. They were certain the problem lied with the truck.

Truck was checked out by the dealer and given a clean bill of health.

Reconnected the TV and TT - no signal. TV was connected to another TT on the lot to test and it worked, so we knew the problem was our TT.

The main cable on the trailer was replaced without success. They disassembled the brake drums and found a disconnected electric brake wire - on the passenger side of course.

Perhaps a wire within the brake assembly has worked itself loose. That would also explain intermittent signals.

[Marine71-76]

Originally Posted by Dkastner

...snip...

The main cable on the trailer was replaced without success. They disassembled the brake drums and found a disconnected electric brake wire - on the passenger side of course.

Perhaps a wire within the brake assembly has worked itself loose. That would also explain intermittent signals.

That is exactly what happened to us...1st time, the brake wire broke and was wrapped around the spindle & the 2nd time, the brake wires corroded & broke.

[ARoamer]

I was having a trailer disconnected error often with my 2020 Chevy 3500 pulling our 2020 5er. During it's first service visit the dealer checked all the truck wiring and found a bent pin in a connector for the 4 way flat connector circuit which I never used. Everything else was fine.
Tech said the new trucks are very sensitive when detecting a trailer connection and the plug connectors must be very clean for that to work correctly. The dealer left a small jar of GM dielectric grease and said keep the connectors clean and apply the grease. It fixed the issue. Keep your connectors shiny and greased!

[Scott91370]

Every one that I have seen this happen to the poster reported it being a ground wire issue.

[ARoamer]

Years ago before dash warnings were a thing I had a 5er and it's brakes were intermittent. Drove me nuts, checking wires, grounds, connectors. Finally I got a pair of wire cutters and started "isolating" each wheel. Sure enough, I found the intermittent one. Figured 3 brakes that work all the time was better than 4 that worked sometimes was good enough to get home on. Pulled the hub on the problem axle at home and found a magnet wire was misrouted and was rubbing on the hub. It's insulation had worn through and was shorting out the brakes randomly.

[KBinAZ]

So I made it home just fine. No brakes. No Problem. Just decided never to stop Actually, just took it easy down the big hills. I did try to clean both the TV and TT plug/pins before I left but that did not appear to help. Thanks for the suggestions. I will check the brakes and make sure there is nothing wrong there. Come to think of it, the trailer did brake funny the morning just before it started. It would kinda jerk and bounce a small bit.

[66lincoln]

Check NHTSA and Tundra forums for failed 2016-2018 Tundra IBCs. Seems to be a common problem; mine included.

[travelingjw]

I carry QD electronic cleaner and use it anytime I am in a "moisture" condition. I spray into any of the connections and have never had a "connection" problem with the plugs.