IAC issue, cleaned, replaced, nothing helps.

[Tampa_T4R]

I’ve searched this issue extensively.
P0505 code.
Thought it might need cleaning so I cleaned it and still code, but it was an aftermarket one, so I bought an OEM one and still the same code.

If I unplug the connector, it starts idling erratic, plug it back in it’s a smooth idle... In park it idles at about 1100 and in drive around 800. Is this correct?

I tested the connector for power and both sides of the connector (open and closed) are getting power at the same time, should that be the case?

I’m starting to think my rig is starting to show signs of a screwed up ECU as I do have another issue that could be ECU related too.

It doesn’t really seem to be idling poorly at all honestly, just the light is driving me nuts.

 

[Brian.]

YouTube

Full video on JUST testing the IAC, step by step so you can know, beyond a shadow of a doubt.

 

[jgue467]

Has the PCV valve and connections on both ends been checked for solid sealing?

 

[Dieselchessy]

P0505 isn’t exclusively an IAC issue. It just means the ECU can’t controll the idle to target.
Could be PCV, vacuum leak, throttle plate position, IAC, coolant temp/volume), ect...

800 and 1100 seems high. Maybe a vacuum leak providing extra air?

Search for threads where folks are trying to correct a “high idle”.

 

[mmw0k7o]

This may help...

My High Idle... CURED!!! - YotaTech Forums

 

[Tampa_T4R]

Already mentioned in my main thread, but figured I’d post here too in case someone has the same issue.

The ECU was the culprit of this issue!