^ be cautious about dealing with auto computer exchange. rightly or wrongly, i don't know, but they've got a poor reputation.

--the thing is, its impossible for us to tell who's right--

one example. some people seem to end up worse off with the new pcm than the old.
https://dodgeforum.com/forum/1st-gen...built-pcm.html

 

maybe a vacuum leak? because of the change of rpm with A/C on-off

 

dhvaughan - this is 'automodulesourceusa'. they say it's a free lifetime warranty. I have never bought a PCM for any vehicle before, so I appreciate the heads up about autocomputerexchange. I have dealt with my share of bad replacement PCM's on customer cars back when I was a tech and know what a nightmare it can be. Even had some bad one's come through that were factory. But their cars were never just one DTC, they were multiples or multiple system failures, no starts, etc. But 150 vs 399+ I am tempted to take my chances and see how it goes. Either I will have a good recommendation for someone else with this issue, or a bad one.. I don't mind being the test dummy every now and then Just want to get the problem solved. Love the truck but it's becoming a headache and making me miss the v10.

checked the Bundle score of this company and they receive a 90/100 ranking them #14 in electronics for their area. I can't find any negative reviews for them, but tons for the site you listed. So I guess I will give them a shot.

 

generaljr - check for vacuum leaks the best I could with a can of brake parts cleaner. Sprayed all vacuum lines I could find, even sprayed around the intake manifold. None of the usual surge or stall effects that one would see with a vacuum leak. Also looked down into the intake manifold with the throttle body off and don't see any signs of a leak in there. I still have that voltage issue on the #3 wire to the IACV where it wont flash the test light like it is supposed to. The other 3 wires flash it fine. Not saying I don't have a leak, I just can't find it if I do.

 

If the place you are looking at is "Auto Computer Exchange", skip them. They have a HORRID reputation. You are far better off spending a bit more, and getting one from a local parts store.

I agree with your assessment though. Given that everything else checks out, PCM is last thing left.

 

sorry buddy, just giving ideas on what to check before spending on a PCM, though about the vacum leak because you told there is something related with the ac actuation and idle change, and the ac sistem works with vacuum, really hope the pcm fix your issue, but just in case try to keep yours until you try the new one

 

HeyYou - It's not them. They are based in the same area of Florida though. I wondered if it was the same business with a different name, but no way for me to check that. They both have different phone numbers and mailing addresses and appear to be 2 different businesses. Guess I am just going to try my luck and see and report back on it when it gets here and I get it installed.

 

generaljr - it does make sense. That's why I rechecked for a leak again. Just couldn't find one. I read that if the Power Steering pump, or A/C compressor were putting excess strain on the engine that could throw the code. But that also leads me back to the engine not being able to adjust the idle properly once that strain is released. Definitely something I will have to poke around at more just incase there is an ever so tiny vacuum leak somewhere that I am just not seeing.

I ordered the PCM tonight, so I'm stuck with it at this point, worst case nothing changes and I will know it's not the PCM. Actually cheaper this way for me since I'd have to have the truck towed to a shop for proper diag's since it's not state inspected yet.

As far as vacuum goes, I don't have a handheld gauge anymore, took mine out of the box the other day and it fell apart in my hand. Learned the hard way not to store my tools in the shed anymore during the humid Virginia summers. But I don't hear any type of hissing when I shut the truck off other than some small valve in the front passenger side of the engine compartment with a green cap on it and 2 vacuum lines going to it. No idea what this is, my other Ram didn't have it. So I will have to find some pictures online and see if I can identify the part and what it does and if it's supposed to do that.

editing to add i believe it's called a duty cycle purge solenoid. And I also found out there is a vacuum reservoir under the cowl, and a cruise control vacuum line that routes near the battery which is known to go bad. These things will be checked Sunday

 

try the new one, but don't give up your original pcm unless the new one fixes your problem.

 

generaljr - ok so going back in again to check for vacuum leaks.. I found one! The elbow coming off the intake that goes to vehicle climate control, speed control, and 4x4 axle had a piece of black electrical tape around it that was coming apart, when I removed it, or actually crumbled the tape off, i found this chewed up elbow (see pic)

going to replace with some scrap tubing I have laying around for now until I can get a new elbow. Thank you !






replaced that with a piece of tube from a 97 Integra evap canister I had sitting around, it's hook shaped so worked perfect. When shutting off A/C the RPM's appear to stay pretty steady. Still have my p0505 but at least I know this potential future problem is temporarily fixed.