Throttle-valve switch: how to check

[oak]

I have reason to believe that my throttle-valve switch is not working - can I check if it is working while it is still attached to the throttle body? If I replace it, how do I position it correctly as it can be rotated slightly about its horizontal axis. It has a 3 "pin" connector - one line power, one signal and one ground (I guess).
Thanks.

[ianc]

Just to get you on the right track; it's always helpful when you post the year of the car you're inquiring about...

ianc

[Steve W]

3.2:




964:

[oak]

Sorry - car is an 80 sc

[fumanchu]

interested also....82 sc here.

[oak]

I got a used part and bench tested it with a volt meter. On the switch, the connectors have numbers that were molded into the plastic cover. The top connector is #2 and I grounded this to a 12 volt battery (the negative terminal); I then attached the power to the lower connector (#3) to the positive terminal. The middle connector is labeled #18 (the signal) and I attached my volt meter to it - with one wire grounded to the neg. battery terminal. The shaft of the switch can then be slowly turned and at some point the meter will read 11 to 12 volts - assuming that it is working.
I repeated this procedure with the old switch still attached to the throttle body and indeed found that it was good. If you do this, be very carefull not to gound the battery when connecting the wires to the switch. I had some alligator clips that I got from Radio Shack and I then taped them to prevent any unwanted shorts - it will be a very tight area when working in the engine compartment.
What I still don't know is how to position the switch - I assime that, perhaps, 1 mm movement of the throttle plate should trigger the switch?????????????