I'm having a problem with my Blazer not shifting sometimes and the ABS light comes on. The code I got was (Vehicle speed sensor low imput). Would the speed sensor cause it not to shift? Also where is the speed sensor located. I've heard that there are 3, on the front wheels and 1 on the transfer case. Do all need changed? Thanks for you time.

 

The ABS sensors are located behind the rotors... just follow the wire harness to them. Try pulling them out and wiping the gunk off with a clean rag... that worked for me.
The speed sensor the runs the speedometer is on the tranny (2wd) or transfer case (4wd) near the rear drive shaft. Follow the wire to it, but I doubt your problem lies there if you have a ABS light.

 

What was the specific code?

If it stated the VSS (vehicle speed sensor), then it is talking about the one at the back of the transmission or transfer case (depending on drivetrain configuration). A problem with the VSS can also trigger the ABS light as it is used to determine if the rear axle is locked. It also can affect shift timing.

I would remove the VSS and see about cleaning it off.

 

Thank you very much. Yes, the code was specific (P0502 vehicle speed sensor low imput) I was afraid it was a major transmission problem.
I'll clean or replace the sensor.
Thanks again.

 

Please do let us know what you find!

 

Thanks for the information guys. I took out the VSS and cleaned it, while I had it out I noticed that a wire had worn through in one place. I think that was why my problem was only on occasion, probably the bare wire was shorting when it touched the metal. Anyway I got the wire fixed and the VSS cleaned and hopefully I won't have anymore of that problem. I was so afraid it was a major transmission malfunction. Thanks again. Great site here with all kinds of good information.