I'm new here (obviously) but i have an old problem that I haven't solved. About 6 months ago I parked my truck for 5 minutes, went back out, and when I started it and drove off the ABS and Brake lights were on and my speedo wouldn't work until I hit about 25 mph. I've been running like this for a couple months as it hasn't seemed to effect anything performance wise on the truck. I recently had the transmission rebuilt, and now the speedo doesn't kick in until about 40 mph which bugs me.

Has anyone else had this problem? I imagine it has something to do with tone rings on the axles (I know the Jeep axles use some sort of tone ring for speedometer and ABS functions) or some sort of sensor, but I really have no idea where to even start.

Suggestions?

Cody

 

Sounds like your speed sensor located above the diff on your rear axle. I just recently had issue with this....... if you check your PCM you'll probably have an 0500 code.

I've yet to do the R+R,......but am told $35 at your DC dealer,......and a few minutes of your time will take care of it.

 

Yep, Vehicle Speed Sensor on rear diff. Takes less than 5 minutes to change out!

 

Sweet. That I can handle. I had envisioned pulling apart the rear end to figure it all out which isn't appealing in 100* heat.

Thanks for the help.

Cody

 

Could this be the same problem on a 1994 2500 4x4. I dont have the speedo problem but abs and brake lights.

 

It could be Dawgo, but on your 94 if you have the RWAL (rear only) system there is a wire that you can ground with the key on and the system will flash the codes using the abs/brake light. It's a black two pin connector with one blk/wht wire in it. I believe it's located over on the passenger side right below the dash on the 94's. It could possibly be over near the e brake pedal right below the knee bolster (i know that's where the 95s were). Another thing could be a fuse (back up or brake lamp) and you also have a vacuum sensor under the hood that can trip the light due to low vac, or I have seen a few of the sensors fail.

 

I seems like from what I keep reading here that if you have an auto you get the speedo problem as well. The manual trans don't seem to get the speedo problem when the rear wheel sensor goes bad.

 

I hava had a hell of a time trying to find the diagnostic connector, my truck has four wheel abs, the book syas there is a 16 pin connector below the drivers knee bolster, but if its there I am blind! I will look for the one JBody speaks of and see if it is less invisible. The ABS has shut down which the manual says will happen. Finally fixed the fuel gauge, easiest tank drop I have ever done!!!!