I recently bought a 98.5 24v Cummins pickup. I've had this truck for about a month. I've recently noticed that my speedometer doesn't work right. It works fine sometimes, but most of the time it just bobs up and down. Also noticed the odometer isn't working right either, skips miles while driving. I watch the counter and sometimes it will move only .1 of a mile in over a mile. About a week ago, I noticed the ABS and BRAKE light had come on. Wasn't on when I bought the truck. Could it have anything to do with it? I bought this truck with 187,000 miles on it and I'm affraid because of this problem, the truck may have more miles on it. Anyone ever come accross this?

 

loose wire or got wet on the servo....................on the drivers side fender well......check it out there ...............

 

Nothing seems loose. I guess it could be a wet wire, but how would you know which wire? Noticed cruise control won't work either. ABS and BRAKE light are on constantly. Any other ideas? Anyone?

 

I would replace the servo I spoke of and see what shakes out...............if that dont work you also may look at the wheel speed sensors and maybe the one on the transmission

I do believe its in the main module on the fender well though

 

its most likely your speed sensor, its like 80 bucks at autozone mine did the same thing. Its located on top of your rear pumpkin...two bolts and plug, in and out in like 15-20 minutes.

 

Is there anyway to test these, the servo or speed sensor? Will they show up on an ODBII scan?

 

So I fixed the problem yesterday. It was actually the wire going to the speed sensor on the rear diff. It had wire exposed so I rewired it and covered it with heat shrink rubber tubing and a plastic weather guard tuber. Should be good. My problems were the speedometer and odometer weren't working, cruise control not working, and my ABS and BRAKE light were on. Anyone else with these symptoms check your speed sensor on top of the rear differential. Thanks for the help guys.

 

yep all those things are the same things mine did...glad ya got her fixed