I have a 99 Jeep Cherokee. Sometimes when I turn my left blinker on, both of my tail blinkers will come on. Im guessing theres a crossed wire or something?

 

Do you have a trailer plug? Check it out if you do. And Jeeps don't have blinkers, they're called turn signals.

 

I had the same problem with my '98. I had just put on the trailer wiring, so I took it back = same problem. It is the multi-function switch in the steering column. The one the turn signal arm is connected to. If you look at a wiring diagram of it you will understand. It mainly happened on mine when I used the left turn signal. Dealer probably has them in stock.

 

I forgot to say they are not hard to replace. You don't have to take the steering wheel off or anything too hard.