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Speedy Squirrel Speedy Squirrel is offline
Rocket Scientist
Join Date: Jun 2008
Location: Detroit
Posts: 896
The stepper IAC is actually kind of like TWO dc motors that work to balance each other at a specific "step". One acts as the driver, and one as a brake. This gives it the ability to hold at a specified point. To go in the reverse direction, the current through both motors is instantaeously reversed using a circuit all the H -bridge.

The above is a big simplification, and enough engineer talk already. Basically there are two types of GM IAC's. The two bolt kind (which people are referring to as the Clewett valve) and the screw-in kind (which Motec uses). The pins are arranged differently, but they work the same. See the diagram below.

PurpleHaze is using the Clewett valve in a Motec world. Referring to the diagram below, he just needs to reverse two pairs of wires at the IAC and hw will be cool.

125Shifter needs to add all four wires AND make sure that he has them connected to the correct pins on his ECU. I can tell him which pins if he tells us which ecu he is using.

DonE appears to have crafted a Magnificent throttle body and attached the TECII IAC adaptor to it. How did you make such a beautiful thing?
Old 08-04-2008, 10:39 PM
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