Hot Wiring

[hermit]

Got home today and went to unplug the boat- almost got burned!  The harness that connects to the truck was super hot, too hot to keep a finger on.  As far as I can tell the wires themselves weren't hot, just where the harness (4 flat) connects.  All four pins were hot.  Is this a sign of a problem?  Lights work fine.  Thanks for any input.

 

[YodaMage]

Heat is almost always either the sign of an overload or a short. I seriously doubt an overload as everything in the circuit SHOULD be protected. So I do suspect a short. Something is not making good contact and is arcing. apply some dielectric grease to the plug and see what happens. If cool, think about replacing plugs eventually. If still hot....then onto the next question like tracing what might be a bad wire with a crack or gap in it.

[hermit]

I'll have to check it out in the driveway more thoroughly.  The wires around the harness weren't hot but there could be a problem elsewhere, I'll go over it all.  The wiring on the trailer is pretty new and I had to mess with the wires on truck end of the harness last year to get a good ground so that's the most likely spot, though why all 4 of the pins were hot doesn't make sense to me.  There is an adapter between truck and trailer, maybe that's faulty.  Thanks

[mudflat]

My guess would be that your plug contacts are corroded, probably on the female side, and the heat is building from the resistance the corrosion causes.  Could be a problem inside the adapter also causing high resistance.  If you had that bad of a short to ground in your wires to cause that much heat I would expect you to have blown a fuse by now.

[adirondackice]

I had that happen once before...so I left it unplugged until I got home to inspect it...assuming a broken wire or bad ground....found nothing and it works fine now...So I am at a loss as well...maybe just a bad connection...

[momay4000]

Hermit,

 

I agree with eveyone here - somewhere you have a short which is causing the heat build up. Go searching for the short, whether it's corrosion in the plug or somewhere downstream in the trailer itself, but I wouldn't ignore it b/c where there's heat, there can be fire.

 

Please give us a follow up post on what you find,

 

Chris

[jimski2]

Trailer ground systems are inadequate. Always add another ground wire from your tail lights to your vehicle connector. Road salt corrodes your vehicle connector and it should be cleaned to a shiny finish.

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[Xxx]

Trailer ground systems are inadequate. Always add another ground wire from your tail lights to your vehicle connector. Road salt corrodes your vehicle connector and it should be cleaned to a shiny finish.

Sent from my SCH-I405 using Lake Ontario United mobile app

All the guys are correct it's a ground fault somewhere, I would inspect where the grounds connect in the light fixtures them self check the light sockets make sure they are not rusted if so spray them up with a penetrating fluid such as (I use Remington gun oil, has rust inhibitors and Teflon lube, and other goodies to protect metals, works well) and then go to the truck wire cluster and check the ground wire should be white and it should come into a box, I had to jump to the other side of the box to get a good ground. I ran a separate ground from my trailer to the plug, not just relying on the ball itself for the ground, this should eliminate the excessive heat problems, check out what size fuse your running, with that much heat that should have blown!!  Hope this helps PAP. F&F Starter & Alternator.

[hermit]

Thanks all I'll start by cleaning all the contacts and checking the light connections.  And the fuse.  I redid the wiring and lights pretty recently but water does tend to corrode things quickly!  I'm more suspicious of the truck.  Last truck I had to run a wire from the battery to the frame to get a good ground.   This one already had issues too.  It's not grounded through the ball I do have a wire for it. Any tips on how to clean the inside of the connecters?  I don't have a wire brush that small.

 

Jimski you mean double up on the ground wires?  I can do that or use a heavier gauge for the ground wire.  It'll have to be attached to the wire coming from the plug though so I can't run a heavier/additional wire straight into the plug.  I'll update when I get it figured out.

[Frisco]

If the connector was hot with the lights off it shouldn't be a poor connection problem because there isn't any load or amps involved. I would check for a ground on one of the hot legs of the trailer and there is a good chance that there isn't enough fault current generated to trip the fuse causing excessive heat.

 

Identify which terminal is the ground for the trailer. Unplug the connector and test across the prongs with a 12v test light, if the test light comes on any of the wires feeding the lights it will identify a ground where there shouldn't be one.

[hermit]

Frisco I should have mentioned but I drive with the lights always on.  Will check what you suggested.  Thanks

[jimski2]

Run a single wire of the same gauge as your largest wire from the mounting nuts of your tail light fixture to the other fixture

and up front to the white wire of your connector. Also run the vehicle connector white wire to the vehicle frame on a clean spot. Never depend on the coupler ball for a ground connection. Trailers as they age corrode and the grounding circuit fails.

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[hermit]

Haven't had time to do too much, did clean the contacts and shine them up with 200 sandpaper. Have a utility trailer hooked up now and it's fine; next test is the boat trailer but I'm going to do other checks as well.