OK so upon my quest to figure out my erratic idle on my 95 F150 302, I decided to go ahead and replace my IAC and clean the throttle bodies, so after I took the TB off, I noticed that 2 of the 3 wires from my TPS were missing their plastic coating and were touching, only the orange wire was covered, so I got a new TPS. Well I went to change out my IAC and noticed that it had a different connector. So I decided to clean mine up and reinstall it till I could find the right one, however I followed my manual and it said to check the voltage across the two pins of the connector with the key on, engine off. So I did, however no voltage was read, but I put the positive lead on the red wire and grounded out the negative on the truck somewhere and I got about 12v. I am thinking that I have a bad ground, its the white wire with blue stripe. Or did I take the reading wrong? And if I did do it right and have no ground, how hard is it to break down the harness and redo the wire?

 

The ground is controlled by the computer, so I would expect to see what you found with the engine off. What did the manual say you should see?

 

Ok so the manual says - To check voltage signal from the PCM, turn ignition key on(Eng not running) and with a voltmeter probe the wires of the terminals of the BPA- ISC Valve connector, it should be approx.10.5 volts. However when I did this check I got nothing unless I grounded out the neg lead on my meter and the positive lead probing the red wire. Also the voltage from that reading is 12.41v. I did disconnect the connector from the IAC and drove the truck and it made no difference except when starting the truck(disconnected-didn't idle as high) and when turning on the ac the idle dropped and did not adjust. But after cleaning the valve last night the truck is surging but only a couple hundred rpms! Still getting about 8mpg and idles rough at a stop, and hesitation under light throttle while driving.

 

Solve this issue yet? I'm having THE EXACT SYMPTOMS as you. I've racked my brain about every possible issue.

 

same issue on an 01 f150 4.6 mine even gets voltage on other ground like yours. Any solutions??