99 ram 3500 van dreaded 0505 trouble code

[joedogs]

i have a 99 ram 3500 van.with a 360 engine and around 65.000 miles.i also have the dreaded p0505 trouble code with a constant check engine light on.i have tried pretty much everything i have found on this and other site to help fix the problem.(checking and cleaning connections,inc pin connection to and from the pcm.replacing,tps,both 02 sensors,iac and cleaning the area where it goes.checking all vacuum hoses and connections all grounds).still no change.i can clear the codes with my cheap scanner and turn the light off.but once i start it up again the light is right back on.sometimes i don't even have to start it just turning it to the on position will put the light back on.through all this the van runs fine and idols pretty well(maybe a bit low but this could be my imagination).this would not even bother me but my state inspection is due and im pretty sure its gonna fail because of this.there is one thing.i dont know if this makes a difference.but when i use my scanner. when it reads(CAT) it always say not ready.all others come out either ready or n/a.no matter how much i drive it this never seems to be ready.local auto parts guy says only other thing is to replace pcm.(of course he has no way of checking mine)any help before i spend another 300+ bucks would be appreciated.

[Chump]

Have you replaced the IAC motor and checked the wiring to it?

P0505 Idle Air Control Motor Circuits

SYMPTOM
P-0505 IDLE AIR CONTROL MOTOR CIRCUITS

WHEN MONITORED
At key on and battery voltage greater than 11.5 volts .

SET CONDITION
The PCM senses a short to ground or battery voltage on any of the four IAC driver circuits for 100 msec while the IAC motor is active.

POSSIBLE CAUSES


DTC (HEX) not equal to freeze frame DTC (HEX)
IAC # 4 driver circuit shorted to ground
IAC motor driver (IAC # 1) circuit open
IAC motor driver (IAC # 2) circuit open
IAC motor driver (IAC # 3) circuit open
IAC motor driver (IAC# 4) circuit open
IAC motor defective
IAC # 1 driver circuit shorted to ground
IAC # 1 driver ckt shorted to # 2, # 3, # 4
IAC # 2 driver circuit shorted to ground
IAC # 2 driver ckt shorted to # 3 or # 4
IAC # 3 driver circuit shorted to # 4
IAC # 3 driver circuit shorted to ground
IAC motor circuit wiring harness intermittent def
IAC motor circuit wiring harness intermittent def
PCM def (IAC # 1)
PCM def (IAC # 2)
PCM def (IAC # 3)
PCM def (IAC # 4)

[joedogs]

iac has been replaced and here are voltages i got from the 4 wire connector(ignition switch on).purple-black 12.49v,black-white 2.9v,yellow-black 12.45v,gray 3.2v.thanks for your time.