Does anybody know how to tell if i have the iac and the tps plugs backwards one has 2 contacts and one has three, but i am not sure what goes where? Not much changes when i swap them. Any ideas?

IAC uses the three pin.

" IAC uses the three pin."

Once again, not knowing the YEAR makes us guess. Wire colors would help too.

The IAC went from 3-pin to a 2-pin with LH 2.4.

So I'd guess the user has LH 2.4 injection, since the TPS is 3-pin on all LH versions.

What puzzles me is how a 3-pin plug can fit a 2-pin socket??? I looked at my 2-pin IAC, and there's no way a 3-pin plug would connect. What am I missing (besides a few crapped out grey cells)?
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

sorry, this is a 85 740t. both the iac and the tps are 3 pin

So both plugs are the same physical size, but one has only 2 pins?

Must be 1 pin missing. If they are both the same size, each should have 3 pins.

Which 2 are still there? (outers? middle and 1 outer? any pin numbers?)
What wire colors are on each plug and pin?
What FI system, LH 2.2?
700 FI harness or other? Same year as car?
(Don't think we're playing with a full deck here.)


The ECU might get a false WOT signal if a TPS plug with a missing pin is plugged to a 3-pin IAC (depending on which 2 pins are in the plug).
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

here are pics of my 2 and 3 wire plugs on a 86 760t known to be oem

here are pics of my 2 and 3 wire plugs on a 86 760t known to be oem

"86 760t" harness plugs? Now that's news. What's your next wild card going to be?

Sorry I'm no help, but digging out the facts one at a time is a drag.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

Found it, i guess i fried my ecu, i swaped it with another one, and the iac is working fine now. Thanks for all your patients and help. you all have been more help than those on "tbricks" Thanks again

Glad to hear it's working. Wish I could have helped but there were too many "unknowns" for me to put anything together.

I had an idea that the the +12v on iac center pin might have jolted the ECU if iac plug was put on tps by mistake.

And I'm still confused about that 2-pin plug. If the iac and tps are both 3-pin items as you said, what good is a 2-pin plug?

Win some lose some.
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Bruce Young
'93 940-NA (current) — 240s (one V8) — 140s — 122s — since '63.

bruce, if you would like i will send a link to pics that i took of the plugs, the first set is off of my 740, the second two is off the 760
http://i2.photobucket.com/albums/y43/daveb272/DSC00976.jpg

http://i2.photobucket.com/albums/y43/daveb272/DSC00975.jpg

http://i2.photobucket.com/albums/y43/daveb272/DSC00974.jpg

http://i2.photobucket.com/albums/y43/daveb272/DSC00973.jpg

Hey Dave, I'm going by memory but I recently had the IAC valve apart on the '89 740 (a mistake I think as it was a PITA to get the case back on without moving...arg). BTW, mine is LH 2.2 (007 AMM) and I believe it was a 3 prong plug.

I can look again if needed, let me know.
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Norm Cook Vancouver BC; 1989 745T 204,000KM