Manual control of IAC motor, DIY_EFI Digest V4 #590:

[Al Jurenas]

| Gary,

If it's like my 90 GM, the IAC is a stepper motor. The pintle is on a worm
gear, and rotation moves it in and out. The coils take turns to rotate the
pintle by 90 deg. At any time, one coil is in an 'enabled' position and can
rotate the pintle in either direction, the other coil is in a neutral
position (will not cause the pintle to rotate).
So you apply a voltage to Coil A, the pintle will turn 1/4 rev in some
direction. If it doesn't turn, then the other coil is enabled (needs to be
activated first). The opposite polarity (on coil A) would have turned it in
the opposite direction.
Apply a voltage to the second coil (coil B), and it will rotate in the same
direction another 1/4 turn, or back the way you came. Switch polarity if
necessary.

You can build a stepper switch with one DPDT latching-latching switch and
one SPDT momentary-center-momentary switch. This will let you move the
pintle in or
out, one step at a time, by toggling the SPDT to alternate sides..

Hope this helps, and I hope my info is correct.

Al
| ------------------------------
|
| Date: Tue, 19 Oct 1999 07:53:07 PDT
| From: "Gary Moulton" <gmoabrim at hotmail.com>
| Subject: Manual control of IAC motor
|
| Can someone tell me which terminals of the IAC motor runs the pintle in
and
| out? The wiring diagrams show two coils and the connector has 4 terminals.
| Does one coil send the position back to the ecm and the other is a 12 volt
| reversable dc motor?
|
| Application is 1994 Mopar 4.0L EFI in a 1982 Jeep CJ-7, and what I want to
| do is be able to manually adjust the idle lower than the 750-800 rpm when
| off-roading. I have connectors and a harness and some electrical
experience.
| I plan to have a switch to disconnect the IAC from the system for manual
| control and a spring loaded switch to "bump" the IAC position in or out.
| There is a company offering such a controller for more money than I think
it
| should cost to build one myself. Thanks in advance
|
| Gary M
| gmoabrim at lasal.net
|