You can use the test light to test for a break in the circuit. One end close to VSS and the other close to the PCM. As for "at speed", that would require a break out box (about $700) or a "fabricated" tester which will measure the frequency. You will still have to put it in the passenger compartment while driving unless you have access to a chassis dynamometer (the types used for smoke emissions or your regular dynos at the speed shops).
Edit. The other thing would be to "ohm" the VSS as suggested in an earlier post from Autozone. You do need a DVOM for that.
Last edited by Tony2005; 08/20/06 01:33 AM.
