I believe my IAC is wiring is off. (see link for type) http://sonic.net/~mikebr/crower/gm_iac.html

So I am trying to figure out the signal it receives from the ECU. So my question given that the IAC has 2 coils and I assume one drive the pintel to the seat and the other away from the seat is there current going to one coil or another no matter what step or position it is in or does the signal only continue until the pintel move the required steps? I have a ECU out of a 93 camaro as well as the wiring harness. It is controlling a ford 460 in an 82 Jeep J10 pickup. ( a true hybrid)

 

The IAC is a bi-polar stepper motor. A google will bring up a bunch of info as it is an industry standard.

Both coils are always powered up. The driver in the ECM will power the coils with the proper polarity to move the pintle.

RBob.

 

Thanks for the input. I noticed several diagrams assigning polarity to the 4 pins so are those diagrams inaccurate in that the polarity changes depending on the direction of the motor?

 

Yes, diagrams are incorrect as the polarity changes to step the motor. No, it isn't due to the desired step direction, but just to get it to step.

RBob.

 

Thanks maybe you can give me some direction with this next question. I think I mentioned that my IAC seems to be working in reverse closed at startup and then it opens up as it warms. I suspect that the wiring or polarity maybe reversed. My IAC pins are labeled A B C D and it would be helpful to know which pins should be Positive and which ones should be negative when the ECM is signaling it to close. At least I would have a starting point to figure out the correct polarity or wiring? What do you think?

 

 

A=IAC "B" low Lt. Grn/Blk
B=IAC "B" high Lt. Grn/Wht
C=IAC "A" low Lt. Blu/Blk
D=IAC "A" high Lt. Blu/Wht

 

Thanks again for the info. I need a little help with the interpretation...."B" means coil B? Low means Negative? High means positive?

 

B is coil B, Bipolar Definition " an electrical line signalling method where the mark value alternates between positive and negative polarities".

 

That went way over my head . I might be oversimplifing this but what I was hoping to find is to acheive a fully open position step (160) what would be the polarity at the 4 terminals. For example would:

A = +
B = -
C = +
D = -

Or some other variation?

 

One count represents one change in polarity which equals one step of the stepper motor