This started a few months ago.
The car hadn’t moved for a month or thereabouts. As it was cold, I was expecting that there might be an issue with the battery.
When I arrived at the car, it did not respond to the remote; no beep from the alarm and the doors did not unlock.
I opened the door in the old fashioned way, by putting the key in the lock. No reaction from the alarm; no beeping.
Put the key in the contact and turned – warning lights came on in the normal way for their test, then off again. Turn the key further; starter didn’t budge, voltage didn’t drop, no noise at all from the starter, nothing!
Try to start the car with jump leads. 15v registered on the dashboard volt meter, but still no reaction when try to start the car.
Breakdown service was called and the car was started by resetting the system by disconnecting and reconnecting the battery.
A week later; same issue but not able to reset the system by disconnecting and reconnecting the battery. Breakdown service was unable to start the car either.
“Check Eng” light is going out at the end of the warning lights test; which according to information from forums means that the car is immobilised.
I check with my number 2 remote and number 2 key; no difference.
Took the battery out and gave it a good charge with my smart charger; no difference, except that the alarm was now sounding whenever the battery was connected.
I have tried several times during this process to reset by disconnecting and reconnecting the battery.
Immobiliser system and alarm are controlled by the one control unit located in the boot near the petrol filler.
Immobiliser system consists of (logically):
- Remote control
- Sensor to receive signal from remote control
- Key with chip
- Keyhole “Halo” in steering column to detect chip in key
- Immobiliser/alarm control unit
- Engine control unit
- All the wires in between the above listed bits
If there was an issue with two remote control units or the receiver, then the car would work with the keys.
If there was an issue with the two keys, the car would at least respond to the remotes.
That leaves the control units and the wires.
Immobiliser control unit was removed and sent to Autotronic in Leicester, UK. They tested and tested, found nothing wrong, then returned the unit to me.
I put the unit back in the car, hoping to be lucky, but the car was still immobilised, although the alarm was now no longer sounding when the battery is connected.
Next up, I swapped the Engine ECU with two others which are left from a rather taxing episode about five years ago. The spare ECUs are not perfect; I would not want to drive the car with either of them in; but the car previously started and ran with both. Neither of the spare ECUs make any difference, so I have now put back the ECU which has been in the car for the last five years.
By my reasoning, that leaves the wiring. I struggle with electrics. I know to disconnect the battery before fiddling with electric stuff, but that’s about it.
The local Jaguar dealer says their old computer diagnostic set up for these cars only half works, so I’m reticent to go down that route as, particularly with the car blocked in park, moving it to the garage to be inconclusively and expensively tested does not seem like good value.
I have also done/checked the following:
The inertia switch in the right foot well is OK from what I can tell (this shuts down the fuel system only? In which case, it’s not really a suspect).
I opened up the gear changer and bent the little metal tab to be sure it is making contact with the gear lever when the car is in park.
I’m near the end of my patience with this. The car is an absolute beauty, has had significant work on its suspension and brakes, not to mention a new headliner and a modern sound system, so it will be a shame if she has to be scrapped (due to insurance and space issues, I can’t really keep the car around indefinitely if it doesn’t work).
I know there are a great many really knowledgeable members on this forum; I would be really grateful for your help.
Thanks, Jeff

 

The 48 pin connector ( BT4 ) above the fuel tank may have become unlocked and migrating off and loosing pin contact . Don't try too hard and break the lock pins . Mine came with a tywrap to keep the lock bar over . The immobilization pin on the ECU is RED 35 and is a digital non - discrete signal . Green / Black wire There are 2 tabs that pinch the pin on the socket side and will unpinch or break off leaving only 1 and no pinch . Replacement sockets # 344113-1 can be found here if needed :

https://www.3waycomponents.co.uk/36-...-Connector-Kit

The inertia switch does not always reset and can be jumpered with a paper clip in the connector on the 2 white wires .

There is a " Hard Reset " beyond removal of the battery terminals . But for non - US models there is a radio system security code concern before doing so .

Shall we play .

 

 

Thanks Lady P, I checked both instances, but still not working.

 

Ha ha, I'm not strong in electrics. How could I check?

 

I like this kind of problem and if you were 800 miles closer I'd offer to try and fix it for free.

If you're not confident with electrics then this may be difficult. I feel sure there is just an electrical issue here.

When you say you "Immobiliser control unit was removed and sent to Autotronic in Leicester, UK" do you really mean the Immobilizer Module (near the steering column) or do you mean the SLCM (Security Locking Control Module) which is in the boot?

This is a long shot, but please check Fuse 4 in the boot fuse box. This controls the Immobilizer Reader/Exciter and the Immobiliser Module.

If you're willing to get hold of a digital multi meter (they only cost a few pounds) and learn some electrics I'm sure we can help get a bit further with isolating where the problem might be.

 

There is a good reference to follow on the Fluke meter brand websight to be up to speed on how to read for different things .

http://en-us.fluke.com/training/trai...damentals.html Click on the pictures to the instructions page for each function picture .

And

Digital Multimeter Basics online course

Depending on how good you are a good investment in time before you are to wrap you head around a problem and put a meter to it is to line draw in the wires with different colored markers that way it becomes more clear and not get lost in the pile of spaghetti . You have all the diagrams and can paste the pics from the PDF in a paint program but have to convert it back to a PDF . Put on a flashdrive and take it to a office supply / print shop to make a very large print . This investment in time will make it less likely that you would get frustrated or intimidated and give up . The 1997 X300 wiring guide does not want to be able to copy a pic for this purpose .

A sign of a good mechanic is they ask questions . There is no such thing as a silly question and you can always PM someone .

 

Dear Brendan,


Thanks for your response and offer of help.



I mean the SLCM located next to the petrol filler; it was sent off to Autotronics and tested as having no problem. I did not know that there was an "immobiliser module" in the steering column. Is there something I could check there before buying a digital multi meter?


I will head out and check, probably re-check, fuse 4 right now.


Shame I don't live nearer.


All the best, Jeff

 

Hi Brendan,


Fuse 4 checked and OK.


Best,


Jeff

 

Lady P, Thanks for the multimeter links. I'll have a look soon. Best, Jeff

 

Yes there is another unit between the coil (halo) on the ignition switch and the SLCM.


Search ebay for "X300 Transponder Module" or "X300 Reader/Exciter Module" to see what it looks like. Communications between the modules is through data links so testing of signals is not really an option. But testing continuity of the wires and testing power and ground between modules would be a good place to start - that's why you will need a multimeter.


A multimeter is also the best way to test a fuse rather than an eyeball check which can miss some hairline failures.