Throttle Position Switch, 1990

[Bill R.]

an automatic , in that case here's the procedure from bmw.

I'd like a verification on the Throttle Position Switch on a 1990 535i. I have the Bentley service manual, page 130-8, upper right corner, shows the TPS as being basically 2 switches, one closed at the idle position, one closed at the full throttle position. I can measure the closed position on the idle, but can't measure it on the full throttle position - the switch shows 200+ ohms, but varies - but it's not a dead short for sure. Can someone verify that pins 4-5 on your TPS are shorted when the throttle is full open?

This TPS is about $150, so I want to be sure it's bad before I get a new one from BMA.

History: I set the TPS perfect at the low end, closed at idle (using a good ohm meter). Then at full throttle I never got the switch closed - always open. Yesterday I worked backwards, thinking maybe if I rotate (adjust) the TPS at the top end for closed, the bottom end (Idle) would take care of itself. I could get the top end at the 200+ ohms point, but not a dead short. The bottom end was close, so I left it. The car runs fine at idle, but I'm not sure I'm getting the 'boost' at the top end.

Thanks for any help.

sc

[scott 4991]

Thanks Bill, this is the same procedure in the Bentley book. As this is a mechanical connection, I can not see it going bad - this is why I'd like to see if someone can check theirs to make sure the resistance at full throttle goes to zero ohms. If so, mine is bad for sure. If their's goes to 100 ohms, mine is more than likely OK. I do not read near 0 ohms at full throttle.

sc