i am testing my idle air control valve. FSM says apply power(+) to the 2 middles terminals and touch ground to other terminals. valve should move up and down. when i touch them the valve just pulses....no movement......so i bought another one.....did the same thing....pulses...no movement....should it spin or pulse when out of the vehicle?
IDLE AIR CONTROL VALVE (1 Viewer)
- Thread starter dani cee
- Start date
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What year?
What motor?
The IAC valve is a stepper motor.
In order to move it, you have to sequentially apply power to the terminals.
What motor?
The IAC valve is a stepper motor.
In order to move it, you have to sequentially apply power to the terminals.
ppc
M Go Blue
Like Jon stated the IAC valve is a stepper motor. The fact you feel the pulses indicates it most likely working properly. Each pulse will result in very small movements. It will take somewhere around 120 pulses for the valve to go from completely closed to fully extended.
If you are having idle issues then you need to clean the throttle body passage the IAC modulates.
If you are having idle issues then you need to clean the throttle body passage the IAC modulates.
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- Thread starter
- #4
91 cruiser 3fe motor. Yes applied power.... motor would react but not spin when applied to other terminals
- Thread starter
- #6
I've also noticed on the plastic part of the iac valve there are a couple hairline cracks....
ppc
M Go Blue
Are you sure you are following the FSM testing procedure properly strobing the S1 - S2 - S3 - S4 terminals in sequence, repeating that sequence multiple times.
What problem are you trying to diagnose you have never stated that?
What problem are you trying to diagnose you have never stated that?
You don't understand how a stepper motor works. The IAC moves in VERY SMALL INCREMENTS with each pulse on sequential poles of the motor. Its not supposed to "spin".
- Thread starter
- #9
It moves on a screw and as it spins in steps of 4....s1 to s4 it should move up (closed) and then s4 to s1 it should move down (open). It is not moving at all. Just a pulse but no movement. Maybe those hairline cracks are the culprit...?
- Thread starter
- #11
Yes following fsm steps and pulse but zero moment....
- Thread starter
- #12
I mean inside the valve there is an electric motor that spins on a screw that moves the valve up and down....
Because it is moving incrementally with each pulse. As stated earlier, it will take about 150 pulses to move it from one end stop to the other.
You keep looking for a motor to "spin", but that's NOT how a stepper motor works. There are 4 coils with 2 commons. Both commons need +12 and a sequential grounding of S1-4 will only move the motor fractionally each time.
You should also consider that you purchased a new one and it reacts the same way.
- Thread starter
- #14
It was a used one.....news ones are like 500 bucks....but thank you all for your input....I will keep you informed
Do you have a dial caliper set? Or some other kind of similar measuring device? If so, check the movement (or lack there of) of the plunger. As it has already been said, the movement is very fine. But it should not be so fine that you cannot pick up a single step, even with the cheapest of dial calipers.
- Thread starter
- #16
Excellent idea I will try this today. I will let you know.
- Thread starter
- #17
I want to thank every one of you. you were all correct, my iac valve is working fine.....the movements are so small you have to keep doing over and over to see a change.......you all saved me about 500 bucks.....i also found the water flow through on the valve was clogged. no water was getting through the iac or the throttle body.....cleaned it out getting water now...........
again thank you all....
again thank you all....
