Left tail light doesn't work (license plate side) - HELP!

[michaellaf]

I have a 1998 TJ that I bought used from another guy. He had a whole set up for an amp and a subwoofer, and I ended up getting rid of the subwoofer, therefor I had to get rid of a lot of different cables that we're not used. Ever since I did this, for some reason, the left tail light does not work anymore. I've tried installing another new light (LED version), and it still isn't working, meaning I know it isn't an issue with bulbs or whatnot. I've also installed a new light on the right side and this one works fine. I have thought about grounding issues but I have used a cable (one that's already on my new light) to ground it directly on the body, on one of the holes that's used to fasten the light to the car and it still isn't working.

I'm worried that the other guy, who set up the sound system, rerouted the left tail light connections to his new set up to save space or wiring (I've noticed some amp wires meet up with what seems to be taillight wires, somewhere in the body, behind the driver seat), so I would've disconnected some things when removing useless cables, but I'm not sure if that's a valid issue.

Also, even if the right tail light works fine, when I turn the right blinker on, it flashes fast as if something is burnt out, even if nothing is. Is this normal? And obviously the left side blinker also blinks fast, since it's not working at all.

Is there anyone who has any idea what the issue might be?

 

[TJ Jim]

Have you put a voltmeter to the plug to see what’s happening? The wires are in the bundle along the drivers side. Have you followed it and searched for previous owners screw ups? There’s a wiring diagram here on the forum, have you checked wire colors and traced any of them?
Led lights are polarity sensitive so you gotta make sure ground is ground and hot is hot.

 

[michaellaf]

Have you put a voltmeter to the plug to see what’s happening? The wires are in the bundle along the drivers side. Have you followed it and searched for previous owners screw ups? There’s a wiring diagram here on the forum, have you checked wire colors and traced any of them?
Led lights are polarity sensitive so you gotta make sure ground is ground and hot is hot.

Thanks for all the good advice, I’ll try my best to follow wires and see where’s what. As for your last bit, the original lights also stopped working when we moved stuff around. Would you think that the ground was put inside the car, where his amp and sub set up was? The amp is grounded as well, maybe he used the same cable/area

 

[TJ Jim]

Ground is one of the screws that hold the taillight on

 

[michaellaf]

Ground is one of the screws that hold the taillight on

Yeah I’m aware, but I was pretty confident that my grounding was pretty solid where the screws are, and it still wasn’t working. Ill try again maybe.