I read some posts about this but did not get a clear indication on what sensor was replaced. The symptoms are ABS/Brake Light on no Speedo below 25mph...Thanks

 

It's the VSS (vehicle speed sensor) on the tail of the transmission.
The speedo is working above 25mph off of the abs wheel sensors at the front wheels and the rear diff (if you have 4 wheel abs).
The ABS/brake light is on because it needs all the sensors alive for the ABS to function properly. If it were an ABS wheel sensor the difference would be that the speedo would work normally.

**If you truck is only equipt with rear ABS only, it is possible that the problem is the rear wheel speed sensor mounted at the top of the differential.
Pull the plug off of it and measure the resistance acrossed the pins on the sensor, if the curcuit is open, the sensor is bad.**

 

I think I just learned something. On my '99 5 spd, the speed sensor was on top of the rear diff. I guess the auto's are different.

 

Speed sensor on the rear my man. I lost many of them. When you pull it out see how muck metal particles are on it. I kept losing mine and never figured it out till after 6 of them. If it has lots of metal particles on it, check your pinion shaft for bearing play, also can pull the diff cover and check the carrier for bearing play. And inspect the cover magnet for metal shavings. My lsd went and took out my rear. Turned out expensive.

 

Auto's have two of them, the one on the rear pumpkin, and the tail shaft of the tranny.

They both need to be happy for everything to work.


phox