Hi.
My car is a 1996 Jaguar X 300 and I had an Immobilizer issue 6 months ago.
I sent the GEMS 6 control Unit of my car to Toledo Sytems to unlock it.
As soon as I install the unlock GEMS 6 control Unit, the car has started.
After one week the car does not start again and the car is totally dead.
The battery it’s new 7 month old.
It seems there is an issue with the Body Processor Unit.
I have already bought two from eBay but after a few days the car won’t start.
I send an email to all the companies who sells parts for Jaguar, and unfortunately they do not have.
Do you know if I can buy a reconditioned Body Processor Unit or even a new one if possible?
Thank you
Mike

 

To bring the picture out :

The starter enables may in your world region involve the immobilizer ( chip in key ) decoder / transponder located near the ignition key that contributor Brandan ( B1MCP ) has a good pic of

This decoder gets it's power from trunk fuse X , it comes fwd through the large 48 or so pin connector ( BT4 ) above the fuel tank

The power for your body processor module ( trunk fuse Y ) also comes through this BT4 connector ( summation of all your starter enables / agreements to close starter solenoid relay ( does this relay click ? swapping options ))

The connector can be tricky and break the external lock pins that pull the connector halves together

Check to ensure there is a tie wrap on the lock over bar holding it clamped closed

The through the sheet metal halves have sheet metal material that may have interference , tricky to align half into cutout hole to bring the 2 together

Ask questions

Your BPM is just plug and play and does not need programing , best to install with battery positive post cable removed , there is a BPM , SLCM hard reset ( back to zero state ) for the X300 that does not effect the engine ECU

When you have the ignition key in run but engine not started you can remove the single relay in the corner of the 5 fuse boxes with the exception of the left engine bay fuse box ( only runs car horns so swapping option )

the relay in the corners must close to power fuse # 10 , 12 , 14 , and 16 in all 5 fuse boxes , fuse 1 - 9 and all others are directly wired ( hot at all times ) to the battery by the big power post terminal on the fuse boxes , there are some loose nuts on other battery cable terminal posts that you can not see ( work involved to get to them )

Do not over tighten the battery positive post bolt and never install battery in backwards ( positive post car fwd )

There are battery shims ( really ) that go over the battery posts if the battery cable clamp has stretched at the clamp over the years

 

I edited the past post including more info , I off and will be back in morning USA

 

Thank you very much for the information.
I didn’t mention that the car won’t even crank. All the lights on the dash are on but the car it’s totally dead.
Yesterday, I tried 20 times and it crank once for 2 seconds and then nothing.
The car is at the electrician and I will give him the information you provided me.
I will let you know how it goes.
Thank you and all the best

 

In order for the starter to rotate the large starter solenoid relay must click closed , relay swapping option as headlights , fog , A/ C clutch of the same LNA part #

The PBM provides a ground path for this to happen

The BPM adds up all the enables / agreements before providing this ground

No fuses to look at at this point but the engine ECU is one of the agreement as one of the fuses 10 , 12 , 14 or 16

In order for these fuses to be powered the small relay in the corner of the right engine bay fuse box to close ( swap option left engine bay fuse box relay )

To test have the key in run but not started , remove the relay in the corner of the right fuse box and it must click in your finger tips

Another agreement is the not in park switch ( off the top of my head ) that if you move the gear shift lever slightly to the cars left you should feel with your finger a clank on the ignition key barrel ( key barrel lock solenoid )

You can with a medium gauge jumper wire and blade type wire ends between socket 3 and 5 get the starter to rotate confirming the starter motor , starter solenoid , and the power to them




Large voltage sag during the point the starter should be rotating ? should only see about 1 / 2 volt starter sag at the instrument cluster

Good battery test and never install battery in backwards , positive post car forward

Never overtighten the battery positive post bolt , breaks curved special nut underneith

 

Thank you again for your help.
I have to take your latest information to my electrician and hopefully he missed something.
The electrician told me that he checked all the fuses and the problem is the Linear switch module on the J gate gearbox selector.
I had some issues before and I could not start the car on P so I moved the gear selector to N for the car to start.
Sometimes I had to move the gear selector even on N a bit back and forth.
Now, I can not move the gear selector from P, so I removed the screw from the J gate selector and used a screwdriver in order
to move the gear selector to N.
A few days ago I ordered another Body Processor Unit as my mechanic told me that the problem should be the Body Processor Unit
which gives the signal to the linear switch module for the car to start.
I will keep you updated
Thank you for your help and time
Mike

 

The linier gear shift switch can be opened and cleaned with a pencil eraser as the tiny fingers / wipers get fluid contamination from above

Not the easiest to remove from shift box

There are 3 upgraded switch part #s and in this Oliver Marks pic is the long black box on the car's right

On the 3.2 liter , supercharged , and V - 12 the linier switch provides a enable in the form of a ground path to car frame , it is a " feeler " from the BPM as a small voltage going to zero ground

On the 4.0 liter it is a little different and more commonly discussed and some confusion arises thinking about one version or the other

The 3.2 liter , supercharged , and V - 12 liter does not have a called rotary position switch which is on the cars right mounted on the transmission

 

if you can't change out of park it is more likely that gearshift interlock solenoid, the gearshift interlock relay or the brake switch have failed as opposed to the BPM failing.
the bpm tells the solenoid to activate when the brake is pressed but it is far more likely it is either not being told the brake is pressed or the solenoid is not doin what it is told as opposed to the computer not doing its job.