stepper IAC isnt moving at all

[williamb82]

ms2, v3 board. firmware is v2.3 as far as i can tell. car has been running for over 4 years on this setup with no issues. just trying to add the iacv.

Following the directions and what others have done for the 7mgte, i installed these jumpers

JS0 (under the processor socket) to IAC1A (near the DB37 connector)

JS1 (under the processor socket) to IAC1B (near the DB37 connector)

JS2 (under the processor socket) to IAC2A (near the DB37 connector)

JS3 (under the processor socket) to IAC2B (near the DB37 connector

S12C to the hole marked JS9 (+12C)



Then wired the IAC accordingly


S1(pin25 on db37 connector) goes to pin D
S2(pin27 on db37 connector) goes to pin F
S3(pin29 on db37 connector) goes to pin A
S4(pin31 on db37 connector) goes to pin C

Got the info from here on wiring the valve
http://saturnwiki.net/wiki/index.php?ti ... trol_Valve

and here is a video of the valve moving wired this way by the guy that posted the info

http://www.youtube.com/v/7pt8E32L5dA&hl=en_US&fs=1&





mine however doesnt move. ive tried multiple iac's that are known to be good. also tried them on the stimulator by soldiering leads to the board. verified continuity from the leads i soldiered to the js0-3 pins on the v3 board. i tried reversing the polarity of the coils in the iac one at a time. no change. doesnt move the iac on the car, nor on the stimulator.the iac1 and iac2 ports are not enabled. when coolant temp changes, the steps on the iac gauge change, but the iac itself does not. need help sorting this out.

[DonTZ125]

I notice you didn't mention having +12v wired to pins B and E, as shown in the fellow's write-up. Are these connected?

[williamb82]

They are not wired to +12v on the megasquirt. only on stock ecu applications. I have confirmed this with many other toyota installs ive found writeups for as well. they all seem to wire the iac the same way i did and it works. 4 wires only from the ms2 and no +12v to the center pins. the ms2 supplys +12v and gnd to the 4 pins in alternating patterns to rotate the iac stepper. I did install the jumper for the +12v to the circuit inside the ms2. it is the 5th jumper. the gray wire in my pic. js9 to s12c.

for a test, i connected the 2 leads to +12v, no change.

edit: also, according to this, i should not conect +12v.

http://www.msextra.com/forums/viewtopic ... 4&start=20

this is a unipolar stepper, wired in a bipolar configuration.

[williamb82]

ok, i got it sorted out. i installed tuner studio, and even though i made sure that the iac ports 1 and 2 were off in megatune, they showed as on in tuner studio. turned them off. burned to ecu, powered it off and back on, then i was getting a humming/vibration from the iac, but it wasnt moving. connected the 2 center leads to +2v, and now it moves, though backwards. closed at cold temps and open at 180. so i reversed the table and its now working like a champ! going to wire the 2 ceter pins of the plug on the car to +12v then connect the megasquirt back up and see how far off the table is for cold idle etc...