Trailer wiring
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Trailering
Joined: Aug 2023
Posts: 21
Likes: 2
Trailer wiring
I have a 2021 F250 with a 6.2 l. Are you recently purchased a 2022 stealth snowmobile trailer with LED lighting and the truck does not have LED lights. Every light on the trailer works as it supposed to until you shut the truck off then the center set of rear top LED lights on the back of the trailer and the 2 rear red marker lights stay on very dim. Or sometimes flash very slowly. All of the fuses on the truck are good. All the wiring on the trailer seems good. I hooked up a similar truck to the trailer and the rear red lights do the same thing. Can't seem to find anything wrong with the trailer. Could it possibly be a setting on the trucks that i'm missing? With the trailer connector plugged in to the truck The brown and green wires both have 2.4 volts with the key off and lights off. The weird thing is no other lights on the trailer are on dim or flash at any time other than the five red lights in the back. Any other suggestions on what to look for. Thanks
Fleet Mechanic
Joined: Nov 2015
Posts: 1,670
Likes: 668
From: DeMotte, IN
Seems to me you should have 0 voltage with the lights and key off. The low voltage would be why those lights are still lit and dim. Look at those circuits. There are plug checkers on the market but I am not sure what they exactly check for. May be worth checking out.
5th Wheeling
Joined: Jul 2017
Posts: 45
Likes: 9
From: Nor NV
If the trailer has electric brakes try disconnecting the trailer battery (assuming it has a "breakaway" battery) & see if the issue is still there. The trailer wiring & operation of the truck is pretty simple, relays and such, so there isn't a lot of voodoo there. My guess is something in the trailer is shorted.
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Trailering
Joined: Aug 2023
Posts: 21
Likes: 2
So I tried a different truck on the trailer and it did the same thing. Hooked both trucks to a different trailer that was the same brand and the same thing happened. I've have checked everything truck side and trailer side and all checks good. Going to disconnect trailer battery as a last test. Not sure where to go from there.... Thanks for all the tips
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Hotshot
Joined: Oct 2006
Posts: 10,137
Likes: 7,950
From: Texas
Whenever trailer lights are doing weird stuff, check all lights for proper ground and check to make sure trailer is grounding properly to truck through the plug, not through the hitch.. It may only take one improperly grounded lamp to cause a “backfeed” and do crazy things.
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I think that’s the truck’s system sending a short, low voltage pulse to the brake pin to see if a trailer is connected. And I think different trailers/bulbs/LEDs react differently to that ‘test pulse’. I’ve seen it on a 7 pin connector I have. It is annoying and I don’t think it should happen.
GMs have issues like this when using disc brakes on their RVs. Sometimes folks report putting a small load resistor in line with the 7 pin connector. Maybe search for some kind adapter.
GMs have issues like this when using disc brakes on their RVs. Sometimes folks report putting a small load resistor in line with the 7 pin connector. Maybe search for some kind adapter.
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