Clearance/tail marker lights on the trailer keep turning off.

It doesn't sound like he asked them to fix it. Once they looked at it he said thank you and left.
It doesn't even sound like he waited for a full diagnosis.

Take up shop time, and you pay for shop time.

 

The only thing it can be is the cord going from the truck to the trailer if it isn't blowing the trailer light fuses in the tractor.

 

Sounds like a bad ground on the trailer side to me. Try tracing the ground wire from the plug to where it attaches to the chassis. It may be loose or corroded.

 

Too much electricity? Tell them to stick that bill. That's a bull#### answer they used to pull one over on you for $105.

If you're losing all trailer lights (signals and brakes included) I'd lean towards a ground issue since ground is common to all the trailer light circuits. Tail and clearance should be 2 seperate circuits on a trailer so I'd confirm if brake/signal lights work before chasing the trailer's main ground.

Coincidences are rare so when 2 (or more) seperate circuits act up simultaneously I try and look at what is in common between all of them.

 

Id give you 20 to 1 odds its a bad ground...

Anytime I do my own trailer wiring I multi ground each circuit... Grounded through the harness, as well as individually ground each light itself.

 

Can you post the name of the trailer shop? It's obvious that was a bs diagnoses and you should let drivers know to stay away from that place.

 

I had a dry van with this kind of problem. The little magic box was in the rear of the trailer, mounted just behind the steel mounting plate for the lights and just under the trailers floorboards. Thats where all the wires come in from the front of the trailer and then distribute power to the different lights. All kinds of crap and corrosion was inside there causing the problems.

On a tanker, that box is usually mounted under the rear belly of the trailer. There is a board inside with wire posts. All the wires in the rats nest go to one or another post. That board/posts will rot away from road salt corrosion if it gets inside that box.

Not hard to replace, but takes time and you better remember which wire goes where. Take some cellphone pictures before ya start monkeying with it. What a way to spend a Saturday too.

 

Lol!........ that's a new one. Did he also recommend new non resistor spark plugs?

 

That’s my point, anyone say this I would have told them to ....


First thing i would do is clean the connectors, once that is done, then go from there.


The other day I was behind a truck, he had his trailer lights blinking on and off. When he pulled into the rest area, I followed him in and told him what was going on, he was baffled. I offered my cleaning kit to clean his connectors.

I showed him how to use it, he cleaned both the trailer and pig tail, and left, followed him out, sticking behind him for a few miles so it was all fixed.

 

Or more likely in my opinion, the driver misunderstood what the mechanic said, and/or miss repeated what was said.