Here is what I did on my swap. There are two wires coming the original VSS on the 700r4. One is Yellow (400 High) and the other one is Purple (401 Low). I spliced them to the LS1 pcm Purple/White (821 High) and Light Green/Black (822 Low). That got it working. Are you doing an LS1 or another Gen III/IV engine. If so the colors may be different. Hope this helps.