1997 Honda Civic 1.6 - P1509 IAC Intermittent

I was able to identify this circuit as being ground side switched. My control wire according to my diagram is black/blue tracer. I performed a solenoid functional test, connector plugged, test light to ground, and my light brought the voltage to ground. Actually, my test light wasn't strong enough so I had to use a jumper wire. Test light lit and jumper wire pulled voltage all the way to 0 volts. I performed a bypast test. Jumper wire to ground, connector plugged in, the IAC reacted. It moved the magnet inside. I peformed the driver and control circuit integrity test, connector unplugged, test light to B+, and my test light lit. The problem is that the test was performed with the KOEO. There was no current flow. Not enegized. So my question is this, how can I find the what's the condition required in order for me to know when the pcm is commanding this output to open and close? That's my variable in question. And by the way, I didn't get a chance to check voltage level at the pcm yet.

Paul nobody’s responding to my problem. Can you help me out? If you have a little time. Thank you.

How many wires going to your iac?

3 wires
feed
control
5v ref

You sure there's a 5V circuit at work? This is the wiring diagram for your IAC:



There should be one key on 12V feed on yellow/black, and two switched grounds on black/blue and orange.

The P1509 code set criteria spells out a output state monitor at work, looking for a voltage state that doesn't correspond with the driver state. From what I can tell, the IACV P circuit opens the valve (more air, higher idle), and the IACV N circuit closes it.

The problem is that the test was performed with the KOEO. There was no current flow. Not enegized.

There had to have been some current flow, or your test light would not have lit. If you were probing the black/blue wire (IACV P, the 'open the valve' wire), then it'd make sense that your test light lit, because the PCM will open the IAC all the way KOEO in preparation for an engine start.

My next question would be if you can get a test light to B+ to light on the orange wire at any point. KOEO or KOER.

Im with tyler on this one. that should be a 12 v feed circuit. Were you using a dmm or a scope on the yel/blk to get a 5 v reading?

I was using my dmm. Ok you got me thinking. I have to go back a retake new measurement readings.

Thanks Tyler I’ll get back to you.