Datamaster says its vss 4000ppm circuit fault. Is this a fault between the vss and the computer of the compuer and the guage cluster. My speedo is going haywire. Ive replaced the vss and put in a new guage cluster and done continuity check from the vss to the pcm and from the pcm to the cluster. All good. Also with the car runing the speedo reads between 10-50 mph when I ground out the wire for the speedo the guage slowly drops to zero. And when I remove the ground the speedo goes back to reading erratic. Any insight?

 

Sounds like your PCM is t!ts up. Only 2 ways I know of to check it. Either replace the PCM with a known good one. Or place a diagnostic signal generator in place of the VSS and watch the output.

Since neither of these options are easy or cheap, I would suggest you look into the output circuitry a little more to be sure there are no ill effects from either shorts to some sort of signal or from any optional electrical equipment installed on the vehicle.

I assume your cruise control doesn't work?

Call a dealer to see how much it will cost to have them hook up the signal generator in place of the VSS.

 

I have a spare pcm that I use for programming and it does the same thing on both of them. Guess my only option is the dealer. Yeah my cruise isnt working either. It went out on I-95 doing about 80 mph back in Nov. when I got this problem. Kept jerking the car around with the speedo going up and down. SH*T. I really dont like the dealer here either