First of all, I messed up. The control wire gets grounded by the Engine Computer. It doesn't apply voltage on the control wire.
I spoke with a Ford expert who said they don't normally check for this voltage. If the system is working properly, the engine will stall when the IAC is unplugged. If stalling does not occur, suspect a vacuum leak.
You might also measure the voltage on the connector when it's unplugged from the IAC unit. If it is there, but not when it's plugged in, look for a corroded spot in the wire, typically a pin in a connector. If the voltage is still missing, measure on that wire at the Engine Computer connector.
Monday, March 15th, 2010 AT 5:58 PM