PCM help needed badly.......been thru all pages for Montero Sport and PCM

Hello, I know I'm new but I'm in a real bind and am asking whoever I can about this problem. I have a 2001 Montero Sport 3.5 4x2 and I'm having A/C problems. The dealership diagonosed a bad CPU, ECM, PCM whatever you call it, part number MR560349, which is only for this year, this motor, this drive Montero Sport. I have gotten two used PCM, since a new one is $1500. Neither work in this truck. My question is is their a reset? are these PCM VIN specific? is there a way to get these to work? are they that tempermental? I kinda find it hard to believe that I can get two from different sides of the country, on from a Sport with 32000 miles one with 58000 and neither work. Any help would be a big help....... I can swap them in, and it turns but does not crank. Put the old one back in, and presto, runs great, and off and on A/C again. The Mitsu dealership says the ground circuit in the PGM is bad, no trouble code or SES......

First, I doubt its the PCM.
secondly, you cannot just install them and have them work.  You need to have your immobilizer system programmed to work with it, and that may not even be possible with a 2001.
I THINK the 2001s were simply reprogrammable, but there were some early cars which required the replacement of both the PCM and the immobilizer ECU to function.   I thought all were switched over by 2001 to the reprogrammable types, though.
whats the issue with the PCM that supposedly is causing the AC not to work?  I find that EXTRAORDINARILY unlikely.

The A/C works and sometimes doesnt. No weird noises, nothing strange. We drove it to a fireworks show last night, 30min away, on the way it quit, so we stopped, turned it off, turned off the A/C(all switches), started the car with it off, then turned on the fan, A/C, and max A/C and PRESTO, it worked! When we got in to return, same order, and it worked all the way home. If we use this order, it will work. The dealership has replaced the A/C button, and Max A/C button, because the max A/C and A/C button had a short in they said, but didnt fix it, same problem. Took it back and they could get it to cycle everytime by grounding the Relay, I tried to jump the low pressure switch when it would shut off, and couldnt get anything. Pressure is perfect in the system everytime I check it. Tapped every part lightly, nothing, but ground the Relay under the hood, works everytime. The DEALERSHIP says its the ground circuit in the PCM, the part thru the computer that cycles it on and off, that the ground is going out, causing the problem. No SES lights, no trouble codes, no other problems. The dealership wants $1500 for the computer, since for this truck it is specific to this year, this setup, this motor, I got two used ones and neither work. I can take out mine, plug in the used ones, nothing, plug back in mine, and it works. I called the dealership, they said even if I ordered theirs off the shelf, you just plug it in, so I must have bad ones. I asked since I have keyless entry, and had seen write ups on cars with Keyless entry, and the dealership said as long as the part number is EXACT, it is just plug and go. There has got to be something else that needs to be done. I have one of the old ones here, and am getting another, so I will have two by this week, one from OR one from TN, and dont get what is up.

quote:

ORIGINAL: fireeatn1

The A/C works and sometimes doesnt. No weird noises, nothing strange. We drove it to a fireworks show last night, 30min away, on the way it quit, so we stopped, turned it off, turned off the A/C(all switches), started the car with it off, then turned on the fan, A/C, and max A/C and PRESTO, it worked! When we got in to return, same order, and it worked all the way home. If we use this order, it will work. The dealership has replaced the A/C button, and Max A/C button, because the max A/C and A/C button had a short in they said, but didnt fix it, same problem. Took it back and they could get it to cycle everytime by grounding the Relay, I tried to jump the low pressure switch when it would shut off, and couldnt get anything. Pressure is perfect in the system everytime I check it. Tapped every part lightly, nothing, but ground the Relay under the hood, works everytime. The DEALERSHIP says its the ground circuit in the PCM, the part thru the computer that cycles it on and off, that the ground is going out, causing the problem. No SES lights, no trouble codes, no other problems. The dealership wants $1500 for the computer, since for this truck it is specific to this year, this setup, this motor, I got two used ones and neither work. I can take out mine, plug in the used ones, nothing, plug back in mine, and it works. I called the dealership, they said even if I ordered theirs off the shelf, you just plug it in, so I must have bad ones. I asked since I have keyless entry, and had seen write ups on cars with Keyless entry, and the dealership said as long as the part number is EXACT, it is just plug and go. There has got to be something else that needs to be done. I have one of the old ones here, and am getting another, so I will have two by this week, one from OR one from TN, and dont get what is up.

you cannot just plug it in and have it work.
As I stated, you must reprogram the keys to the PCM (or more specifically, the immobilizer).

how do i go about getting this done, obvisously the dealership here doesnt know his a** from a hole in the ground, and id like to throw his a** in a hole in the ground. where can i get this done, can i do it myself? they keep saying i can just buy a new one and put it in myself.........i still have one here with only 32k. I have asked the dealership if i needed to get it reprogrammed to the vin, they keep saying no. You keep telling me i need to reprogram the immobilizer, how do i do this?? or who can do this???

far as I know, only a dealer can program the keys and immobilizer system.  Call your dealer, or a different one, and tell them that you CANNOT just "replace" a PCM, as the immobilizer system recognizes each PCM individually.  If you replace either a PCM or an immobilizer ECM, you need to reprogram ALL the keys to the car.
I find it hard to believe the dealer doesnt know this, as all mitsus' have had an immobilizer system for about 7 years.
I dont think there is anyone other than a dealer that is capable of doing this, as you need mitus' software and scan tool.
Perhaps there is someone else, but I dont know of them.

Seems with a little chatting with the dealer, I finally got him to realize what was going on. I have a 2003 Mits Factory Service Manual, and I could reprogram the keys with a handheld scan tool and following the directions. I asked him how I would add a remote, and then started chatting with him about the immobilizer, he finally realized that maybe the PCM needs to be reprogrammed. When the second one arrives, I'm gonna take him both, let them swap them and reprogram each to see which one works best and scan it again. He said hed do this all for $40 so why take a risk. Let ya know what happens, and thanks for giving me a direction to look in so when I called I could get him thinking. Ive never dealt with something like this, I mostly work on GM products, and the keyless entry is totally seprate from the PCM, and usually dealer installed, with a kill to the starter. Ill keep ya posted!!!

just to let you know, you're not programming the PCM.  You're actually programming the immobilizer.  The two componants talk to each other, and when they dont recognize each other (as is the case here), the systems start from scratch... I.E the immobilizer will need to have the keys re-programmed.

A scan tool is in fact needed to do the reprogramming, but a generic, cheap tool is unlikely to be able to do it.   I dont think Ive heard of a single scan tool other than mitus' that will have the needed software to complete this job.