SRS light is on, speedo does not work, have not yet checked to see if cruise control works. Speedo does not move - stays at zero.

I want to test the ASCD theory, but I do not know where the unit isw exactly. I know it is down by the ECU. Can someone please describe it for me?

Also, besides the dealer, where can I get a speed sensor? I have looked on ebay - no luck.

http://www.courtesyparts.com/

I'm no good with the gauges and such. GL

I spent many hours working to get my speedo working. I replaced the vehicle speed sensor in the transmission and the gauge cluster and the speedo still would not work. Unplugged the ASCD and all of sudden, I had a speedo!!! I got another ASCD from Ebay, plugged it in, and everything is fine. So, I imagine my problem all along was the ASCD. The ASCD is under the ECU in the passenger side floor under the cover panel at the front. Really easy to get to. i think there is like 3 10mm bolts to take loose on the ECU, then you can just lay the ECU to the side. The ASCD actually says ASCD on it and it is about 1" thick by about 4" long and silver colored with a black plug. Good Luck!!!

THANK YOU! That is EXACTLY the answer I was looking for. I just replaced the ECU the other day, and I knew that the ACSD was down there s9omewhere, but did not see anything that actually said ASCD on it - but now that I know which one it is, I am stoked!

And I forgot to ask: would pulling the ASCD relay from the under hood fuse box accomplish the same thing?

I don't think pulling the relay will accomplish anything because the problem is that the ASCD is also hooked to the wires from the VSS. In my case I had to disconnect it (get it unhooked from the wires from the VSS) to make my speedo work. If you just pull the relay, the ASCD is still connected to the VSS, but just without power. But it may be worth a try?

No luck. I pulled the ASCD box under the ECU - speedo still inop. Probably the speed sensor.

Any other ideas?

hrmmm well the VSS is really easy to test. Pull it out and connect a voltmeter to the leads and set the range on AC voltage at the lowest level (yes, I still use an analog meter. if you have an autoranging digital meter you won't have to worry about the range but sometimes a digital meter doesnt give you the easy readings for low signals like analog meters do because the display doesnt't react as fast) and spin it by hand. It should pretty easily make about 3 volts AC when you spin it. You can even take the gear off and connect a cordless drill to the shaft and spin it and see if it makes AC voltage. If it is making AC voltage, then the VSS is ok. If the VSS is ok then set your rig up on jack stands and pull the dash apart where you can get to the back of the instrument cluster. You are looking for the leads that go to the speedo itself. Mine were labeled on the printed circuit that is on the back of the instrument cluster as SIG and 2P. Those are the connections from the VSS to the speedo. Connect test leads to those terminals with the same AC range on your voltmeter and see if you are getting AC voltage to the speedo itself from the VSS. (make sure the car is secure and start it and let it idle in 2nd gear on the jackstands, should bring your speedo up to about 15mph if it is working) If you are getting AC voltage to those termnals then I guess the only other answer would be that the speedo itself is bad. Of course, this is all just my opinion.

Ordering a VSS tomorrow - if that does not work, then I guess it's a new speedo itself. Pray for me.

If the VSS doesnt fix it and you have to order a cluster from Ebay make sure you get the seller to send you pics of the back of the cluster. The plugs were changed from 94 and up I think. The wire colors are all the same, but the plugs may be different. Just double check so you dont end up having to do a transplant......like I did. hehe

My speedo never worked sense the day I got my z32 and I just got a GPS with a speedo built in. I opted the lazy way.

Well I am hopeful that I don't need to replace the cluster - I am chanting "the VSS will work...the VSS will work" while offering chevy parts as sacrifice to God. Maybe that's the poblem - maybe Chevy parts aren't a good enough sacrifice.