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Discussion Starter · #1 · (Edited)
Hi all.. new to this forum. Working on my girlfriend's Dad's Taurus. Will be doing it a lot, so I figured I'd better join. lol.

Now, on to the problem. 2005 Taurus SEL 3.0 Dr. Spock motor (Vin U). Car catches, and then dies. I've checked the IAC valve, and the unit is good. Upon further inspection, there was no votage to the harness w/ key on, eng off. Pulled the PCM out of it's little cubby hole, and tested directly from the PCM. No voltage again. When I apply voltage to the IAC via the battery, it does exactly what I would expect it to do, as voltage increases, the RPM's increase, further increasing voltage, further increasing RPM's (once again confirming the valve is working).

So, this tells me the PCM might be fried... but before making that assumption, I have a question.

Can someone tell me definativley if there is supposed to be 10 to 12 volts at the IAC with key on, eng off? If so, can someone please provide factory specs?

If not, feel free to tell me "your doing it wrong asshat! This is what you are supposed to do!"


The noob (to the Taurus)


After walking away for a while it occured to me that the PWS might be negative, and it is (This means the signal from the PCM is a ground signal). So the next logical question is, does anyone know where the key on power for the IAC comes from? All diagrams point to the PCM Power relay. Can anyone confirm or deny this, as the only wiring diagrams I have refer to a 2003.

Edit 2:

Problem found.. it pulls from the #18 fuse under the hood. PCM Keep alive power/A/C clutch relay.. wich makes sense because the compressor clutch locked up (currently bypassed) Hope this helps somebody else....
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