I was driving on the highway tonight coming home from Colorado Springs and right in the middle of the drive, the ABS and Brake lights on the dash came on. Truck seemed to be driving normally and the brakes were functioning just fine when I pulled off the highway, but as I was stopping at the end of the offramp, the speedometer dropped immediately to 0 as I approached 20 mph. As I was accelerating from the stoplight, the speedo stayed at 0 until I hit 20 mph and then it jumped up to normal speed. Driving through the neighborhood at 20-25 mph, the speedometer goes up to 25, down to 10, up to 20, etc randomly until I get about 25 mph or so. What the heck is going on? Do I have a speedo/ABS sensor out or something? Was too dark to look for anything when I got home. Anybody else have experience with something like this? Thanks

 

It's the sensor on top of the rear axle.This is a common failure.I think I paid $43.00 for the part at Dodge dealer,two years ago.

 

I just replaced the sensor on top of the rear diff on my o2 2500 and still have those darn ABS and brake lights on. do the codes need to be reset or ? can't seem to locate the sensor for the front is it on the diff or on each front wheel? dosen't seem to be any wires goin to the front hub areas.

 

It is a very common problem on Dodge Trucks. Other causes beyond the rear sensor are either a faulty brake light switch (at the top of the brake pedal, miss-adjusted brake linkage, or a frayed wire somewhere in the anti lock brake circuit.
More than one person has fixed the problem only to have it return again and again, and again.

 

I have no idea whether this might help....On my 2006 truck if you remove fuse #30 (Spare) the ABS and brake light comes on. Obviously that fuse is not a spare and has something to do with the brake circuit.

 

You might watch the rest of your gages, if they start acting like the speedometer there is a good chance it is your computer going out.

 

I had these same warning lights lit up on my dash. About the same time I noticed I had a open vacumm fitting under the hood so I plugged it up with some duct tape and the warning lights went out. Seemed odd, but they haven't come back on in the 300 miles since.

 

I had the same issue, but mine droped and caught at 15 MPH I just fixed it on Monday. The part cost about $40 at the parts store and took about 5 minutes to change. It is really easy to change if your spare tire is down cause you can sit or kneel down under there, rather than lie on your back and try to work on top of the diff.
If i remember right all you need are a 9/16" and 1/2" wrench, and a flat screw driver to help undo the plug and help (CAREFULY) pry up on the brakeline retaining bracket.
I didn't have to reset anything, i believe that is one of the checks the computer does on start up. My lights were off right after i replaced the sensor.

 

my truck has been doing this lately and driving me crazy. now i know what it is. thanks.

 

I have the very same problem as I previously posted about. I have replaced the speed sensor. I have pulled the wires out of the wire loom. I cannot find any problems with any of that stuff. Could I have bought a bad sensor, or is it more than likely something else ? I had it read on a computer and NO codes came up.

 

Truck at work 02 CTD is having same problem: No Speedometer, Brake and ABS light are illuminated on the dash. Even with a new VSS
Stumped.
Truck runs like hell too.

 

Many of these trucks substain damage to wiring from center of rear axle and up left frame rail. Don't forget the tone wheel in differential could be damaged. Sensor will have ball of "fur" on magnet part generally if have diff damage internally.