help me ID these parts please

[udidwht]

i bought the 12mm IAC and put it in, no real change. FYI what i have figured out is that the 10mm has a single taper and the 12mm has a double taper end if that makes sense. they both measure exactly the same. I'm going to remove it and start the truck with it still hooked up to see if its even moving any.

if not, i think I'm going to try to make a jumper harness straight to the ECM in case i have a problem in the factory wiring. how would i go about finding which pins on the ECM run the IAC, so i can tap into them.

Any idea as to how one can tell which one to use? Any clue in the IAC bore on the TBI itself?

Why a 10mm and 12mm? Anyone know which vehicle/s used 10mm vs 12mm?

 

[udidwht]

I read out of the service manual (pg. 570) that the IAC (7.4L) states specifically the following:

All IAC valves on TBI Model 220 units (except those on the 7.4L engine) are thread-mounted and have a dual-taper pintle. On the 7.4L engine, the IAC valve is flange-mounted and has a dual-taper pintle. Any replacement of an IAC valve must have the correct part number, with the appropriate pintle taper, for proper seating of the valve in the throttle body.

I notice on Rockauto that the Delphi and Delco IAC valves do not show pintle size but they appear to not be dual taper ended (12mm) based on the other listing that show dual taper for 12mm IAC valves. The service manual calls for flange mounted dual taper pintle for 7.4L. Seems the 10mm one is dual tapered.

Also from manual:

No physical adjustment of the IAC valve assembly is required after installation. The IAC valve pintle is reset by turning the ignition “ON” for ten seconds and then “OFF.” The ECM/PCM then resets the pintle to the correct position. Proper idle regulation should result.

Manual also state for the model 220 TBI:

On the model 220 TBI unit, the TP sensor is throttle shaft driven and non-adjustable. Make sure to order the correct TP sensor with the identical part number for the engine if replacement is necessary.

 

[udidwht]

The part number I believe for the "Idle control speed actuator' is #

GM 17084953​

Picture of it here (#16) https://lt-truck-gmc.7zap.com/en/g15+g1500/49295-1994/0-0-1904162379/0-1623891437-0-0/