PCM Help

Looks like my voltage regulator went out in my 98 sport, so I need a pcm. But the problem is the pcm in my Jeep pulls up for a wrangler pcm. Called the jeep dealership to get factory number and the number my vin pulled up comes to a 2000 jeep Cherokee. Jus need so help figuring out what pcm I actually need to get my Jeep fixed!

There are revisions that cover multiple vehicles. I've purchased 2 PCM's here with good success.
https://www.fs1inc.com/jeep-ecu-ecm-pcm.html?make=100&gclid=EAIaIQobChMIlYC6xq_b3QIVDdlkCh2jAwlKEAAYAiAAEgKpWfD_BwE

So I’m trying to help 98xjStacee with his PCM problem and we have it narrowed down to the PCM number he needs. We know his XJ needs 56041534 since it’s an auto and has federal emissions but my question is what does the letters after mean? After doing some research I’ve seen that these letters need to match exactly and I’ve seen that the letters are just date codes and don’t matter if they match. So if anyone else can chime in on what we need, since the letters go from AA to AH, we’d greatly appreciate it.

The numerical part of the part number generally remains the same for the item. The subsequent letters are "revisions or updates" to that part number. For example, 56041534AA would be an older version of 56041534AC.

Perhaps contact the dealership and see what the last version of that part, that they have listed. Maybe a search through RockAuto could shed some light, as they are pretty good about listing current replacement part numbers.

This is from one of FS1's pages......

This Engine Computer also referred to as an Engine Control Module (ECM), Engine Control Unit (ECU) & Powertrain Control Module (PCM) is guaranteed to fit all 1998 Jeep Cherokee models with a 4.0L engine size. The following part numbers are compatible with this unit:
56041531AA, 56041531AB, 56041531AC, 56041531AD, 56041531AE, 56041531AF, 56041532AA, 56041532AB, 56041532AC, 56041532AD, 56041532AE, 56041532AF, 56041534AA, 56041534AB, 56041534AC, 56041534AD, 56041534AE, 56041534AF, 56041534AG, 56041534AH, 56041535AA, 56041535AB, 56041535AC, 56041535AD, 56041535AE, 56041535AF, 56041537AA, 56041537AB, 56041537AC, 56041537AD, 56041537AE, 56041537AF, 56041537AG, 56041537AH, 56041544AA, 56041544AB, 56041544AC, 56041544AD, 56041544AE & 56041544AF

There is another way around this issue. You can add an external voltage regulator and ignore the problem with the ECM.

Here is one source for a kit: https://alternatorparts.com/external-voltage-regulator-high-output-alternator-kit.html

Do a search for "Cherokee external voltage regulator" and you will find a number of things to look into.

If you have other reasons you don't want to pursue this option that is fine. I am just putting it out there in the event you may not be aware of the option.

Welcome to both of you and thank you for going red right off the bat.

Thanks for all the quick responses! Anak I had heard I could do that on my old 24 valve Cummins but never looked into it, so thank you for shedding light onto that. I believe that’s the way I would much rather go cause as of now I don’t see anything else wrong with my pcm

Wondering what make you think the PCM voltage regulator is toast ? PCM failure is very highly unlikely so you should rule all the more common and logical faults and failures before you condemn the PCM.

A useable 1998 junkyard PCM with the correct part number is all you need. The last two letters of the part number, which are the revision code, can be ignored. Unless your state DOT inspection reads the PCM VIN code, the PCM does not require reprogramming.

Tim_Nm I had the alternator and battery checked, tested full charging system and only failure was voltage regulator. Thank you for the input on the letters. The sticker that was on my pcm with the part numbers has since fallen off at some point. That’s why this has been a hassle to try to find the correct one because I have no numbers to run off of.

98xjStacee said:

Tim_Nm I had the alternator and battery checked, tested full charging system and only failure was voltage regulator. Thank you for the input on the letters. The sticker that was on my pcm with the part numbers has since fallen off at some point. That’s why this has been a hassle to try to find the correct one because I have no numbers to run off of.

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Have you ruled out a wiring issue? Checked with a meter at the pin on the PCM to see if it's pulling the pin to ground to initiate charging? Of course slapping a used PCM in there is also a good way to rule out the PCM....