I have been trying to establish some facts about used PCM compatibility, especially in reference to '96 models.

If one wishes to retain ones XJ long term, and travel off-road, this means carrying certain vital spare parts

If your PCM fails far from home, especially off-road, that could spell the end, (same for most any 20-30yr old vehicle)

Summary of what (think) I know, re '96 models;

TCM is same Part number for '94-96

PCM changes to OBD2 in 95/96 models

'96 model XJ will only work directly with an OBD2 PCM from a '95 or any '96 PCM ?

I have reason to believe that a '97 onwards used PCM (post-update body) will not work with a '96 XJ because;


1) the '97 onwards have a factory immobiliser which recognises the VIN programmed into the key and PCM
(this means unless the key and reader is also switched or re-programmed, the engine will stall after 3secs)

2) the '96 has the same TCM control situation as the '95, ( it operates independantly of the PCM, as per FSM)

'97 onwards have a different TCM part num, and it does interact with the TCM to help control the trans, (as per FSM)

If issue No1 can be overcome, (which it can), I do not know whether a DTC would be thrown,
or some trans control issue would be experienced, but suspect it would

sorry about the long post, but where else can I ask such questions?

I have a chance to obtain some '96 PCMs..more later..please feel free to confirm, deny or dispute any of above

 

I cannot speak to the XJ, which I do own a 98 XJ, but I can tell you that the 96 and 97 ZJ are unique and interchangeable and that neither one requires ANY setup at all. My 97 ZJ I just replaced the pcm this year. They are just plug and go. I don't believe it has to do with the imobilizer, which my zj does have, btw. My zj has the full security system, little light that flashes red led on the top of the dash when set, etc. Despite what all the refurbers and sellers will say, they are just covering themselves. Those 2 years are plug n play on the zj, anyway.

 

By the way, Cardone had one at my local advance up the street, on the shelf, they took my mangled old pcm for the core credit on the spot, and the total cost was just about $90. Worked great, fixed a lagging shift issue in the transmission which I wasn't even aware it might.

 

I have conflicting information on post '96 vehicles

They do have factory immobilisers fitted...how do they work ?

it was my understanding the key is programmed with VIN, and the PCM reconises this via a sensor above the key barrel

...hence some used later PCM are also sold with key & barrel...however, I see some advertised without those items ?

if it doesnt work this way, then how ?..am I dreaming ?



I have a 56041494AE PCM from a '99...I could plug it into my testbed spare '96, and see what happens

if it can be sold without the key to someome else, then I would