Steve40th

Is there a simple way to check the signal from the ECM to the IAC to verify the path is good?

RBob

iTrader: (1)

At key-off, short ALDL connector pins A&B together.

Then key-on, engine-off. The IAC will continuously be commanded to extend (closing the port). Placing your hand on the IAC you should be able to feel it clicking.

Don't do this with the IAC removed from the TB. Else the pintle will exit the IAC.

RBob.

Steve40th

Thanks. I already did the test and it aint doing anything. I even took it out, put it in a bag and tried to start it, and turned it to on, then AC. Nothing made that thing move. Doing a resistance test on it showed it was good. Now I need to see if a signal is even getting there to the IAC>

Vader

Connect a dual channel scope to pins C3 (B Low), C4(B High), C5 (A High), and C6(A Low) and monitor the ECM output. At KOEO you should see some pulses for a few seconds, and one signal will lead the other in phase by about 180º.

Steve40th

If it wasnt for the fact I have those available, I would have to ask if a Tech 1 or 2 could test it too?
Is it a signal a noid light would come on, such as when you are checking injectors?

Ronny

iTrader: (1)

Wont a volt meter verify 5V at one of the 4 terminals with key on?

Steve40th

I am sure it will, but I am looking also to see if there is a pulse to the IAC

RBob

iTrader: (1)

The DVM will average the voltage from the IAC driver. Being a 0 to 12 v square wave the DVM should show about 6 volts.

Unplug the IAC, key-on, engine-off. Probe each pin with the other probe to ground. Should get a voltage reading on each pin. If it stays at 0, or stays at 12, then it isn't pulsing.

A noid light should show the same thing is a sense. If it is pulsing the light won't be as bright as if connected directly to 12 volts.

RBob.