Tail light question

[bored4long]

Hi, I'm very new to trailers. We recently purchased a very tired 1991 Excel 5th wheel. I noticed the right signal tail light behaves oddly. When headlights are off, it blinks correctly. When headlights are on, and the lamp is on, it no longer blinks correctly when the right turn signal is engaged (left one works correctly). Instead of getting brighter to "blink" it actually goes off for the "blink".

Any thoughts on where to start looking? I have a multimeter, but am not sure what I could or should measure to troubleshoot.

Thanks for your help!

[partsman01]

I have run a temporary ground wire from rv to truck and it will improve things, then I know it is a grnd problem.

[ddndoug]

Sounds like everyone else beat me to the punch, but.... bad ground.


Doug

[opnspaces]

Yep it sounds like a bad ground and it's grounding through the left taillight. Try pulling that left bulb out and see if it changes the behavior of the right bulb.

[bored4long]

I forgot to mention I have verified the connection to truck is wired correctly. I will definitely check the ground tonight and post an update.

You guys are fantastic. Thanks so much for the quick replies!

[beemerphile1]

Absolutely positively a bad ground of the tail light in question.

[btd35]

Bad ground is a good possibility. You might also see if the bulbs are seated properly in their sockets. If it's the push in and twist type, they may have forced the bulb in 180 degrees out. Saw that happen a couple of times. Open up the plug that goes into the truck and check all connections there to be sure all is clean and done right. You never know what someone may have done.

[tanman32225]

I agree bad ground..

[donn0128]

Bad ground is not uncommon. To prove my theory out, take the tail light assembly off and find the ground wire. Connect a jumper wire from that to the trailers frame. If things work right then you have your answer.