1998 X300 XJSport, immobilized, not cranking.

[Markgenesis]

Bought a cheap XJSport in October, wanted a big car again after driving a Panda 100HP for a while, seemed to run fine, a bit rough at idle, bunged in a new set of plugs, seemed to improve a bit, went to use it for work one morning and it wouldn't crank, had ignition lights but starter was dead, did a bit of research, central locking was also not working (off the fob or the key), engine light was going out after a few seconds of the ignition being on, suggesting the car is immobilized (so unlikely to be starter motor or relay).
All fuses are fine, only have one working fob, two keys but it's the same with both keys, a couple of case studies pointed to the Body Processor Unit, replaced this but it's still the same, also tried the ignition barrel, there is a fair bit of wear in the barrel but spraying with WD40 and giving the key a good wiggle made no difference, any pointers ?, there is a Jag indy in my town but i thought i'd ask on here.

[a8hex]

OK, really stupid question but is the battery OK?
see I said it would be a stupid question.

[Markgenesis]

a8hex said:

OK, really stupid question but is the battery OK?
see I said it would be a stupid question.

Pretty sure battery is fine, fairly new, went from cranking fine one day to dead the next day with ignition lights etc still bright, not even a click or slow churning of the starter just dead.

[Peanut130]

i have had a similar problem on my x300 sov
open the bonnet down the drivers side inner wing about 15" behind the headlight there is a white oblong
connector with 6 or 7 wires pull this apart and clean the pin connections
worked on mine

[Markgenesis]

Peanut130 said:

i have had a similar problem on my x300 sov
open the bonnet down the drivers side inner wing about 15" behind the headlight there is a white oblong
connector with 6 or 7 wires pull this apart and clean the pin connections
worked on mine

Ah, cheers, will give that a try.

[melhookv12]

Turn the ignition on, wait for light test to complete. Then look bottom left corner.
Is the ' check engine ' light on.
If it's not then the car is immobilized.

Also wiggle the gearlever, make sure the car is in park, or even move it to neutral and try that.

The plug mentioned above would cause the engine to be immobilized.

Also the engine ECU gets water in it. It's in the rh footwell, in the A POST.

[Markgenesis]

melhookv12 said:

Turn the ignition on, wait for light test to complete. Then look bottom left corner.
Is the ' check engine ' light on.
If it's not then the car is immobilized.

Also wiggle the gearlever, make sure the car is in park, or even move it to neutral and try that.

The plug mentioned above would cause the engine to be immobilized.

Also the engine ECU gets water in it. It's in the rh footwell, in the A POST.

Engine light is going out, car is definitely Immobilized, also central locking not working, have tried wiggling the gearstick, 'P' light is on, have also tried starting in neutral (no joy), had a look at the plug under the bonnet, looks fine, ECU in drivers footwell is dry.

A jag guy has suggested the Security ECU in the boot (with the fact the central locking is dead), have checked the plugs and connections, they looked fine so have another Security ECU to try, going to give the battery a good charge first though. Will have another look at it over the weekend.

[Markgenesis]

Still no further forward with this, replaced the Security ECU, have central locking off the key now but not working off the fob, new battery's in fob, battery checked, it's healthy, fully charged, checked big plugs under bonnet behind R/H headlight, they are fine, all fuses look good, checked wiring going to engine ECU, looks good, no damp or water ingress, "P" on shifter housing lighting up, engine light still the same, going out with ignition, still no crank, car is not shifting out of park now, going to try the original Body Processor Unit back on.

At a loss really, it's a lovely car and i wouldn't have minded doing the other work to it and getting it nice but starting to regret buying it now (it's tying up the garage and i cant get my bikes past it), starting to loose patience and wondering if i should cut my losses.

[Jagnotcranking]

First of all i hope this even reaches you because the topic has been dead for over 2 years.

Did you ever find a fix for the car/got it running again?

I have a '95 Sov with this exact problem and i'm running out of options as well...