So a few months ago I had an issue with my speedometer. (1996 B2500 cargo van)It was jumping all over the place. I replaced the VSS (vehicle speed sensor) and everything was fine. Until today. It started jumping around again. The shifting issue with before hasnt started back up again though. What could be causing this? Anyone have an idea? I am stumped. Thanks for any help you have!!

 

What ya drivin?

Think I would find someone with a scanner, that can read data, and see if the PCM is getting a good VSS signal.... that will tell you if it is the sensor that is the problem, or the speedo itself. Need to know more about what you drive before I can get much further.

 

I drive a 1996 B2500 cargo van. I was at AutoZone a few days ago and the guy checked for codes and nothing. Then, a few days later, (yesterday) is when the problem started back up again. Before, I noticed it would shift real fast, I mean in a second when i reached 70. Downshift then roght back up again. all in a second.

 

Check and clean the connections at the VSS, see if that helps. If not, physically remove it from the trans, and have a look at the gear, make sure it doesn't have any unusual wear. (check the drive gear on the trans output shaft too.) Make sure the part of the gear that actually drives the VSS isn't bunged up.... give it a spin while you have it out, and make sure it turns freely....

 

Thanks. Did all that. Pulled it, cleaned it, everything looked good. When i pulled it though, I messed something up so i went and returned it (autozone) and got a brand new one. Put it on int he parking lot, started the van and it is still jumping around. Although i do seem to remember it ook a day or so for it to stop last time i replaced the part.
If this isnt the issue, what could it be?

 

If it's bouncing around, you have a wiring problem somewhere..... (or, a second bad sensor....... third?) I think yer gonna have to trace the wires, and see if you can find any damage.

Where is the PCM on your van? Might want to check the connectors there as well.

 

i read the PCM is located on the firewall directly above the a/c compressor. I have no idea where the a/c comp[ressor is though. hahaha

 

Ah, you *should* be able to open the hood, and see it then. (I would think....) A/C compressor is on top of the motor, drivers side.

 

is it possible it could be the OSS? The output speed sensor?

 

I think the PCM only uses that for shift points? Not sure.....