throttle position switch

[backyardbill]

I think the TPS is not functioning right and is the cause of my idle problems and intermittent engine shut down after a full throttle run.

Connecting pins 2 and 18 of the TPS to an ohm meter show that the micro-switch inside the TPS is working correctly. However, Connecting pins 3 and 18 show ground throughout the movement of the TPS. Should 3 and 18 be "open" until WOT?

http://www.glocktech.net/fiat/restoration/TPS.htm

Img 1 shows TPS at idle.
Img 2 shows TPS at WOT.

Thanks.

[spider2081]

It looks to me like the switch contacts are stuck together. Pin 18 is the contact that should move. It has a tab that follows a track in the cover. when throttle plate is closed (idle) connector pin 18 should mate with pin 2 and 3 should be open. At full throttle pin 18 makes to pin 3 and pin 2 should be open. Between idle and full throttle all pins read open to each other.

[backyardbill]

Bingo! That was the problem. I guess the computer was confused when WOT and idle were signaled at the same time. I just bent the bar so that the WOT contacts engaged at full throttle. Man, the Fiat runs really good now!
Thanks.