I have a 2000 Cherokee sport. This new problem just happened today when I went out to start it up this morning. ok, so if you get in and put your foot on the brake pedal before you even put the key in, the instrument cluster lights come on. let off the brake pedal the dash lights turn off. weird right. So I start it and none of the dash lights work including the heater controls and gear selector part in the center console. you push the brake pedal down they all come on. then I happen to notice not only those lights are on but the front parking lights come on with the brake pedal now. so as im driving, every time I get on the brakes the front orange marker lights are on and my dash is lighting up and then you let off and it goes dark. I have no idea where to begin to trace this strange electrical problem down.

 

anyone?

 

Wow, that's a weird one alright!
I don't have a specific solution for you but typically when one circuit affects another there is a short between them or the one is lacking a ground connection.
Is there any aftermarket equipment like a stereo or alarm system that's in he dash? That would be suspect #1.

 

Time to grab the service manual and start looking for a common point (often a ground) between those circuits.

My money would be on a ground problem. Bad grounds = hair pulling. They do some very strange things.

So, when very strange things happen, I start looking at grounds.

 

you have trailer wiring Good pplace to start checking ...

 

I had this happen to me a couple of weeks ago. It turned out to be the right side tail light connector. Corrosion had briged the power to the brake lights to the running lights. Check that connector and the one on the left side for and corrosion. You will have to pull the plastic pannels in the cargo area to access the connectors.

 

Never thought of that, I'll definetly check that out this weekend.