[Tim C]

Well I'm hoping someone in this form has dealt with this issue before.
I'll start off by saying that I just recently had a used engine installed into my 2010 Acadia (timing chain issue). After about a week of having it home I noticed the right tail light was illuminated with no key in the ignition or anyone stepping on the brake pedal. Just all of a sudden lit up and stayed on. I've disconnected the whole tail light assembly for the time being.
Does anyone have any idea where I could start and what the cause of the issue may be? Could this be a ground issue?

 

[Grantv]

Factory type bulbs, LED?

 

[Tim C]

Yes, factory LED tail lights.
I removed the left tail light and plugged it into the right side, as soon as you plug the connection in it lights up as well. So I've ruled out a faulty tail light assembly.

 

[Grantv]

Factory is not LED... that's why I ask; have you replaced the factory bulbs with LED?

 

[Tim C]

I'm not the original owner, correct me if I'm wrong, are these not factory tail lights? There are no bulbs.

 

[Tim C]

Just an update, I was able to find the fault.
I bypassed the factory trailer light(s) harness and plugged the main connection coming from the body directly into the light assembly, voila problem solved. There must be a bad ground connection somewhere between the harness and the hitch receiver connections.