Clearance light failure.

[PaulJ2]

Help, Help. Wouldn't you know I just sold my used 1995 Terry Expo trailer today, and when the people came to pick it up, we plugged into the truck and the clearance lights came on ok in the front but none on the back sides,or back top worked. Everything else works ok. Never had any trouble like that the whole 19 years we owned the trailer. It is in great original condition throughout.
Anyone know where to start looking? Do they run the wires from front to back through the ceiling or maybe the floor? Wondering where to start looking for a broken wire. Thanks for any ideas.

[opnspaces]

Man I was going to suggest that it was the buyers truck, but stopped because I couldn't explain why some of the clearance lights work. Well glad you know what it is at any rate. thanks for the update.

[RVcircus]

Gotta love when it's not your wiring issue;)

[PaulJ2]

Update...Ok all, just for grins I backed up my truck and connected up to the socket and guess what--it works fine! So--the buyer has a grounding problem with his vehicle. There was lots of grease on the ball so it didn't ground there either.
Will help him sort it all out. I have found that when you have a problem that makes no sense it many times comes down to a grounding problem.
Whew! got out of that one! Kinda thought the lights that were working looked brighter than normal also. Thanks all for the tips.

[westend]

Typically, what you'll find is that the lights are daisy-chained (one wire leading from fixture to fixture) with the ground connection being the trailer's skin in aluminum sided models.

I'd suggest to start looking at the fixtures closest to the front lamps that are working. In one of those you will find a bad connection. Good luck.

[PaulJ2]

Thanks all, I will post what I find.

[opnspaces]

I's with Mtnbbud the problem is probably at the fixtures. It might be as easy as pulling each bulb and reseating it in the socket.

[mtnbbud]

Take the bulbs out and run a thin blade through the slots to clean the connectors. More than likely the issue isn't with the wiring, but right where the bulbs are inserted.

[enblethen]

If the trailer has metal skin, you need to start at each light to see if the sheet metal screws are corroded.
Test between a known good ground to the center of the lamp socket for power.
You could run a temporary jumper from known good ground to the shell of the lamp holder.
Some clearance lights are spliced behind the tail lights.