Picked up a clean 2000 WJ 4 0. Learning its personality. The previous owner replaced all the lights, interior and exterior with LED. Everything works for the most part. I am having a couple issues. When headlights are on, the passenger turn signal hyper flashes. Works fine when headlights are off. Drivers side works fine.. In addition, the lights under the dash and the lights that illuminate the climate controls flicker. What should I check first? Flasher relay? Grounds? Any suggestions would be appreciated.

Additional info: Previous owner installed resistors to deal with the hyper flash. Took them off because he was worried about how hot they got. He also told me he replaced relay with an LED friendly one. He also said if you take your foot off the brake, the hyper flash stops, and it does. Unfortunately, that is obviously not practical. Checked bulbs, sockets and fuses. All seem good.

 

That's a classic bad ground. The brake and turn signals share a ground. A poor connection in the rear is causing them to back-feed, making the passenger side hyper-flash when the brakes are on.

Find the tail light ground wires inside the rear quarter panels. Clean those connections thoroughly. That should fix your turn signal issue.

 

In my 01 WJ I used white LED bulbs for all interior lighting except dash and temp control, I used red LED’s. Also used LED’s in the 3rd brake and license plate illumination- no problems. I purposely did not install LED’s in headlights or tail light assemblies for all the issues you described, and, I was totally turned off by the thought of splicing into wiring harness to to install resistors-NOPE!!

 

Thanks. I figured it was a ground. Not sure where the grounds are located. I'll search here and elsewhere for location.

I can't seem to run this down. The tail light assembly has a harness, with a ground wire running in to the rear fender. Is that where I need to look?

I looked at this video:


And it seems to indicate it might be under the front seat?

Anyone have an idea?