I've recently purchased a 2001 Cherokee. Going through it, it's got a good foundation but a few things stick out that I'm currently puzzled about. I'm having a persistent DTC of P0505 Idle Control System. Surprisingly I've made a similar post about a 1998 Cherokee that I had with the same issues. I've initially thought the IAC was bad, and have done some testing and now I'm leaning more towards the actual circuit within the PCM being bad.
I've checked the vacuum connections on the manifold. Sprayed with some carb cleaner to try and find a leak and have not found any.
I've checked the wiring from the PCM connector to the IAC connector and it's all clear with no chaffing or shorting to anything.
I've checked the wiring from PCM to IAC Connector for continuity and they check out fine to their right locations with nothing else reading to each other.
I've checked voltage in the IAC connector with the Key On Engine Off and I'm only receiving around 3.7V to pin 1 of the connector, Pins 2 sometimes will show around .36V but drops to 0. Pins 3 & 4 read 0.

At this point, I'm starting to think the actual IAC circuit within the PCM itself is bad? Does that happen? I find it ironic that this Cherokee is doing the same thing that 1998 I had is.
Does anyone have any insight to this matter or, know of a good PCM dealer to possibly get a new PCM.

 

I read a very similar post to this recently and the OP bought a new PCM, which resolved the issue, and posted a link

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