I have a 1990 XJ 4L. The cruise control doesn't work but the AC and heat seem to work fine. Where do i start to figure this out?

Thanks

 

Electrical. Either the yellow box is not adjusted right or unplugged or missing. The stalk for your turn signals has a bad wiring connection or broken. Blown fuse. I've been fighting with my girlfriends cruise to get to work and still don't work right or even at all.

 

Thanks HBR 13 for the reply, this may sound dumb but what is the yellow box?
Where do I find such and animal? is it truly yellow?

 

Yea it's yellow box it's bolted right under the steering colunm. And says AMC on it.

 

Thanks, I will look into the yellow box in the morning

 

My cruise didn't work when i got my xj..come to find out it was just the vacuum tube..'01 though, not sure if it very different

 

On my Jeep, it ended up being the switch itself. Try renewing the switch or find a replacement switch. Mine only needed a good blowing out with hi pressure air and some electrical contact cleaner...

 

I would begin with the vacuum system. Although the vents work while driving on flat ground, the cruise requires a ton more vacuum to operate.