[jr_ss]

The Z32 is a two wire VSS and I connected only the signal to the DD, the ground wire was left alone. My speedo was working before my car went down for a heart transplant.

I had an issue with it not reading/reading incorrectly when I installed the DD originally. Called up DD and went through the trial and error program. Turns out that it was a polarity issue and I had the ground wire hooked up to the DD. I swapped the ground wire out for the actual signal wire and it read, then I had to get a GPS out to calibrate/set it.

*EDIT*

You need to determine which is the signal wire and which is the ground wire for the VSS. You can do this with a multi-meter hooked up to a lead at a time. You'll see signal when your hooked up on the right one. Once you figure out what is what, you can proceed to hook up your DD. Cut the signal wire where ever you'd like, DO NOT cut the ground wire. If you cut the ground wire, you can solder them back together, no harm no foul there, but it's an extra step. Leave enough wire on both sides to solder another piece of wire to the piece you cut. You'll need to do this on both sides. Use tape, shrink tubing, whatever you'd like to cover those connections. Run the extended wires to your DD. There should be an input and an output terminal on the DD. Run the wire that comes from the VSS to the signal input terminal. This will allow you to alter the signal so that your speedo can be adjusted to read correctly. The signal output terminal should get the other wire that runs to the back of the cluster, which will send the adjusted signal to your speedo. I have all 4 toggle switches pushed up(away from the DD main body) on my setup. This is how mine was wired and it worked as such. As stated above, you will need to adjust the speed at which is indicated with a GPS. PM me if you need more information or help.