Hi, I’ve just bought an X300 3.2 auto 1996 from a friend. It’s been at a garage for 6 months (non Jaguar garage who were struggling with the x300), suffering with a no crank issue.

The garage have finally given up (I think they were out of their depth) and told my friend that it is an immobiliser problem and the car will never run again.

He was about to scrap it, but I have taken it on (and its problems).

So here is what I know - the garage say they have tried a used BPM with no luck. I don’t trust this.

they say by bridging the starter relay behind the headlight the car starts and drives.
the car has a current drain and the battery (a new battery within the last year) drains overnight to flat.
I have noticed the central locking works on the key (although stiff) but not on either fob. One fob lights up fine.
gear Shift lock is stuck and doesn’t unlock at all. You cannot hear anything.

I have ordered a used bpm, but not arrived yet. Any further suggestions would be appreciated.

 

I remember on my X-Type there was a special procedure for pairing fobs with the car. I don't know off the top of my head, but the X300 is probably the same.

As far as the gear shift lock, there should be an audible click when you press the brake. If that's absent it could the the brake pedal switch, shift lock solenoid, or the relay in the center console. With the car in park the "P" should be illuminated. The lit up letter changes as you shift. It is common for the park microswitch to fail or become finicky.

Immobilizer and battery drain are above my head, but they did take the relay bridge *out* right? That seems like it'd drain things.

 

Have a look at the last 2 sections here, the battery drain is a pointer to the switch
Jaguar XJ6; Jaguar X300; not starting; start

 

thank you for this. It’s looking like this extract could be the switch - “Often, one of the relays behind the RH front headlights stays live all the time if this part of the switch is not cutting the power, draining the battery. If this relay remains closed, the ECU thinks the engine is still running so the car won't start.”

I guess if the ecu thinks the engine is running then it won’t kick the starter motor in.. and this would mean why the fob doesn’t work etc. I will check this out today and report my results (I won’t fix it and disappear!)

 

Hope your new BPM will sort it, but if indeed it is the immobilizer that is stopping the car from starting and there is no way to disarm the car, you might wish to seek help from Andy Stodart (forum user name "XJREngineer") to rewrite your engine ECU to bypass security check on start up so the starter and fuel pump will function as they should. The immobilizer is there to suspend both unless the car receives a positive checked security signal within a few (3?) seconds.

 

Update..

so I went back to the car this evening. I worked out the ignition switch was in fact working, as it was responding to the key sliding in and out.

as I turned the ignition on I could see the check engine light went out after a few seconds.

this led me to the security module in the boot. I disconnected the battery and removed and disconnected the module. I unclipped the front of it and slid the circuit board out to see if I could see anything burned or damaged. Couldn’t see anything so clipped it back together. I reconnected it to the car and tried the ignition and the car fired up straight away. And the check engine light stays on when it clicked to ignition only.

I can only think the connectors on the module had got wet at some point and this had led to a dirty connection. I inspected the pins on the module and all looked very clean.

thank you to everyone for the help and support.

anyway, this has now uncovered a new problem - the gearshift is still stuck in park. I used the screwdriver method to remove it from park and it went through the gears and drove fine. The lights illuminated as the gears changed from R to N etc.

so now if anyone has an idea on why this separate problem could be occurring that would be great. Brake lights work but no clicking at the gearshift when the pedal is pressed.

 

so after a week the car is doing the same problem again. Check engine light goes out now. I’ve tried messing about with the module again but no joy. I’m thinking that I need to bypass the security module as you suggested. Do you have a contact detail for Andy as I’d really like the ecu sorted out to solve this

 

Pics coming

With the starter solenoid relay being jumped and it starts is a plus to carry on forward

The body processor module must receive enables for it to command / provide a ground path to close the starter solenoid relay

This will be the left side wires at the BPM in the pic




You have a relay swapping option with the same part # as the A/ C Clutch , headlights , or fog but not the large left # 5 ECU control relay






With the parasitic brain on the battery kicking your butt you can move the small knob on the left of the steering collum from auto to off

This negates the seat and steering movement on ignition key removal ( the security system stays alive draining the battery and not going to sleep by pin 4 to 5 of the ignition switch connector )




The security lock control fuse # 3 or 4 in the trunk must be installed so that it can provide a enable to the BPM

The chip in key decoder must be powered to also provide a enable to the BPM

A quick check is if the tie wrap is on the large BT4 connector above the fuel tank , but do not remove just yet as this can be a pain




For the 3.2 liter engine ( same block and engine regulation as the 4.0 liter ) but has a different version of transmission that does not have a rotary position switch ( starter relay control ground path) so in your researching the 4.0 liter is close but tiny bit different

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Thank you for this brilliant information.

just to add a few more things that I’ve noticed which might be due to the problem.

the remotes (both of them) do not work, and I can’t pair them to the car even though they light up. I’ve tried the pairing procedure a few times and can’t get the car to chime or beep to enter pairing mode.

The battery didn’t drain completely when the car was starting ok, but it did start to go flat after two days.

could it be a faulty bpm after all?

 

thank you so much for this detailed information. I’ve now gone through the car again.

I was going on from what I was told about the bridging of the starter. I’ve now found out with testing that bridging the starter motor relay cranks the car but there is no start.

check engine light is off after a few seconds.

Ive swapped out the BPM - no difference.

I am now thinking this is an ecu fault. I am in the process right now of removing the ecu and checking the connections

 

So I have had a breakthrough.

after swapping out the BPM, dismantling half the dashboard, checking all connections and every relay, I bridged again the starter. The engine turned over quite fast - but didn’t fire.

After some thinking I then attached a jump pack to the car as well as the battery. Check engine stayed illuminated and it fired instantly.

it turns out the battery had enough power to turn the starter well, but it looks like the ecu or some systems didn’t like the fact that it wasn’t fully charged and shut down the ecu giving an immobiliser fault.

I’ve put the battery on charge and my tester says it’s at 40%.

so this I strongly believe is the fault all along. Thanks for everyone’s help.

 

On installing the battery ensure to not install backwards

Positive post fwd , can mark the battery with tape

never overtighten the positive post bolt , breaks curved nut underneith

Somewhere along the way I picked up the engine ECU needs at least 11.4 volts during starter sag for the ECU to function

Below 11.4 volts the startter will still rotate well

The voltage gauge on the cluster is very accurate

" I bridged again the starter. The engine turned over quite fast - but didn’t fire."

for the engine to run the engine ECU has 2 power sources used at all times

Right engine bay fuse box relay , large # 5 right ECU control relay

The fuel pump " control " needs the right heelboard fuse box relay to close at the rear seat