I am having no luck through auto elecs, Jeep dealerships or mechanics in resolving this problem. Maybe someone can advise me.
Today I unlocked my Jeep as per usual with the key fob that opens the door locks and deactivates the car security and immobiliser. The doors open fine, the security light on the dash is not displayed. Situation normal. But the engine keeps cutting out after a second or so as if I had not deactivated the immobiliser. I have two fobs, tried them both, tried starting the car maybe 20 times, cranks fine then cuts out after a second or two. No new work done recently. New battery a month ago. Use the car every day. All has been great.
However in case its relevant, about 2 months ago I had trouble with the key fobs NOT being detected by the car in that I would press the buttons and the doors would not unlock. My auto locksmith checked the old fobs, said they seemed to work OK on his tester. He programmed a new fob with my code and the car still had trouble detecting the signal. It works but not realiably and I have to press hard on the buttons. We fiddled with the buttons and it works OK now most of the time but nobody seems to know what the problem is other than they suspect its the car's receiver/system rather than the key fob itself.
1998 XJ Jeep Cherokee Sport RHD 4.1 L petrol, no mods. Australia
Cheers

 

greetings bro from sunny Australia

if you enter the following search term "how does the immobiliser work on a 1998 jeep cherokee xj" into Google

you will find heaps of info on the AusJeep forum

..including the posibilty you have the dreaded '97 immobiliser..check the oval plate on your firewall

the '97 uses the FOB, but '98 onwards have a key and ignition device, apparently the '97 model is an "export" version and not the same as USA

The apparent fix is a PCM, I know one that sat for 12mths at a big auto electric place in town

When choosing an XJ the 2 things I asked was does the aicon work, and does it have an immobilser (pre 97 dont..yay)

 

Thanks so much for your quick answer. The Jeep is registered as a 1998 but it’s definitely a fob with simple Lock Unlock button options. No panic button. Can you please detail what I should look for on the oval plate? Sorry, I’m not that good at auto mechanical expertise though in general I’m reasonably good at tech things
Cheers. (Hope you’re ok in the fires)

 

what your Australian Compliance plate (and rego paper) says is your Jeep year is often not correct.

There is an oval brass plate on the firewall that is stamped with MM/YY manafacture date..that is what year your Jeep is

my 3 x '96, one is reg as a 95, one a 96, one a 97 !

you should also go to forum member cruiser54 website, download the correct Factory manual

you will need it

I havent looked, but you will probably need to check whether the skim module is recieving and sending a signal to the PCM

 

Thanks for your advice. I can't find the oval brass plate but the compliance plate says 03/98. Going by the VIN decoder from cruiser54 thatyou suggested the 10th digit is a V which is 1997 so I think it is actually 1997.
Anyway in somewhat good news i tried the "disconnect the battery for half an hour" advice and voila, the car starts now. Problem resolved for now but no answer as to why it did it in the first place and when it will do it again.
My VIN is 1J4FJB8S7VL523864. http://malcolm.iri5.net/FSM/1998%20X...ts%20fiche.pdf
There is another plate which seems like it was fixed at the manufacturer on the opposite side form the compliance plate juts below the left side windscreen inside the engine compartment.
attached.


If you have any recommendations for good 'old' jeep mechanics in Melbourne I would appreciate it. I have tried 2 and though they were quite knowledgeable they were sloppy and unreliable, they'd often create a new problem fixing an old one.
Cheers

 

that was a sensible thing to do !..I should have suggested it...always disconnect electronics and reboot..

maybe the "post update" ('97 and later) dont have the brass oval plate

that plate you pictured has lots of info on it..I think if you Google "jeep cherokee XJ data plate decoder" , it will tell..I know it has paint color

The plate data is in the FSM. I recomend you download it and find & read the section that covers the immobiliser

You could join (or just view) the Oz forum, for specific details on '97 immobilisers..and mechanics in Melbourne etc

I live in Newcastle, and do nearly all work on all my equipment myself

XJ are easy to work on, except for the electronics and wiring, so a good auto electrician, that is very experienced, and has worked on them a lot, is a great bonus

 

US models have a sticker on the driver's door edge that contains the date of manufacture and tire pressures among other things. Contrary to popular belief, the security key function was optional because my 2000 doesn't have it. Supposedly, mine has remote entry although I didn't get a fob from the previous owner and only one key. My remote receiver is in the domelight housing. If the key is covered by plastic, it's a SKIM key. If not it's just a plain switch. However, it might be a replacement key cut using a Skim key when it doesn't need to be. IDK if XJs have a halo light around the key switch with the SKIM, but my WJ does.