My pcm was locked out, due to a bad skim module. Ordered and Received a new pcm, with immobilizer disabled. Connected it according to their directions, turned the key.. it started.. and died.
checked my scanner.. immobilizer activated.
sent it back, new pcm received, they tested and given full assurance (with video of their test mule running and screenshots of programming showing disabled).
ive removed the skim module(before installing the previous pcm) and now, have removed the radio (which kept showing to enter a code.. when code was entered, kept saying wait 2 hours, and then to re-enter code)

my questions.. if anyone can help..

1. Could the radio have been the reason the pcm was triggered and enabled the immobilizer?

2. Is there anything else in the truck that could trigger the immobilizer?

ive never had to deal with a skim or pcm lockout before.. my 96 xj was awesome and my 84 xj was a decent..

i want to eliminate anything that could activate it, so i dont have to do the shipping and waiting, again (im in the uk and no one here can do the reprogramming.. and the shipping is expensive! 🙄

im used to doing anything and everything mechanical (im a classic car/truck mechanic/welder/fabricator) but im not used to doing electrical issues on computer controlled vehicles and could truly appreciate any guidance so i can get the truck running and get it on the road..

thanks and hope theres some answers. 😊

 

have you studied the service manual info ?

I am confused by your post though (I hate and avoid immobilisers)

You said your skim module was defective, you have removed the skim module (which is not part of the PCM ?) and fitted a new PCM that is supposed to work without immobiliser ?

Without studying that section of the 98 manual, should you not replace the defective skim module?

If you have a deactivated PCM, why does it want an immobiliser input ?

 

The service manual does not show the immobilizer nor its tied in ancillaries.. meaning, that, while i can isolate the skim module (its the box mounted on the steering column with the ring that goes around the ignition key to read the chip in the key), the wiring schematic, does not show what else ties it unto the pcm, so as to isolate is, to keep it from reactivating the program insjde the pcm.

In the uk, where i am, they scrap/crush the jeeps, because they cannot bypass the immobilizer nor have figured out HOW to, aside from a new pcm with the immobilizer disabled, in the program. It is not removable any other way, and so they junk the good jeeps, because they cant get past it.

something in the wiring, (according to the company that supplied the new pcm (skim disabled and vin# programmed so it will run correctly with my trucks modules) is causing a short or surge, that reactivated the immobilizer program, making it search for the skim module and chipped key.. because it didnt find the skim, it locked the pcm.. and so the i jectors wont function.

what im looking to get answers about..

can the factory radio in the 98 jeep, is faulty, cause the immobilizer to go into locked mode?

What is the easiest, most direct way i can test my trucks electrical system, to find if there are/is any shorts or damage, that could cause the pcm to have issues.?

i have done various visual checks, and all fuses/relays seem fine, (not blown or damaged ((removed, inspected, swapped into different positions, such as cooling fan, into starter relay positions and no issues))) and all wiring not inside the plastic covering through the engine compartment, have good terminals and are not bare wires touching anything else..


nothing seems out of place or damaged..

 

its hard to judge some ones auto electrical fault finding capability

a failed XK immobiler is usually a death sentence here to

afaic the only known fix involves replacing (from a matching wreck, PCM< ignition skim module, ignition switch and key

doubt the radio would be the issue or that anyone would know

without further study there is no way of checking for shorts

google and archive search for the issue, I have seen it before

trying to help here, but my hand is buggerred and i can hardly type

 

no worries..

i refuse to let the truck die, its only got 66,000 miles on it and when i send fuel up the intake, it starts and sounds very healthy..

ive been google searching and youtube surfing.. and no one seems to truly be able to conquer the issue..

i know my new pcm will work.. but i need to make sure there arent any electrical issues, before i connect it..

i work on classic cars and trucks, that arent computer controlled.. and while i can diagnose and repair simple electrical systems..

im not at all familiar with the 98 jeeps pcm and how the immobilizer is tied into the wiring.

 

ok, if you are determined study the FSM and post relevant excerpts re skim, there is no other way to identify what to test

I also work on classic cars, and am a qualified electronics technician

i hate immobilisers just an entirely useless ****ing pice of **** to fail and leave you stranded, it influenced me to stay with '96, no immobilizer

my mate, who is an automotive engineer and auto electrician fixed one as I previously detailed, it had sat unfixed at the largest auto electrician's in our city for over 1 year