Hi. My X300 Sovereign 1996, 4.0L, won't starts, only if I pull off the minus wire from the battery and let off about 10 or 15 minutes. Then, after this time, I reconnect the minus on the battery and the car starts. At the jaguar dealer authorized car service in Bucharest, Romania, they told me that the security module have an error and it is not possible to delete/reprogamme it. They give to me an advice: to buy an IMMO Off... Another guy told me that isn't exists IMMO off for Jaguar & Ford... I'll apreciate any help...Thanks.
PS: This problem appears after my jag stays without a battery almost 3 years.

 

Do you have starter rotation ?

The security locking control module or SLCU can be reset to zero state by a " Hart Reset "

The SLCU is direct wired or " hot at all times " to the battery so this is possible

 

If I don't disconnect the minus from the battery, let disconnect for 10-15 mins and then reconnect, no, the engine won't crank at all.

 

There is a precaution before doing this as the stereo head unit has a security feature in it to prevent it from working if removed from car

The " security code " would have to be reinserted into the stereo

The US models do not have this feature from my understanding

 

Do you have fuel pump relay clicking with your finger on it ?

The fuel pump will stay on for only 4 seconds then off

A 3rd click on is after the Crankshaft position sensor sees engine rotation

This is a safety design

The # 1 fuel pump relay is in this picture

 

There is a large connector above the fuel tank that may be making a intermittent connection

The security wire goes through this , but do not remove yet as can be hard to reinstall

 

What is a "Hart Reset"? Do you know something about immo off for jaguar? Do exists any tutorial on youtube that can be useful? How can I know the security code for my car? Is this code the same with the code for turning on the radio? Can I bypass the immobilise with the security code like in this video?
Thank you.

 

Immo stands for immobilization which is not a device but a function of the SLCU

Another way to look at it is this enables the starter to work by way of the starter solenoid mounted in the starter motor

This solenoid gets power through the starter relay

The starter relay is mislabeled as solenoid the the 1st pic

The 2nd pic is correct

The starter relay can be swapped with one of the same markings except the needed ECU relay ( RH # 5 )

 

Taking off for some errands

 

Back from errand

 

Starting with the stated term from the shop of IMMO off

The immobilizer signal is a enable signal , to not allow a action would be a lack of signal or no signal

In this X300 case the wire between the SLCU and the Body Possessor Module is a digital group of ones and zeros

Unless they had the proper equipment they can't see this signal

For them to say that IMMO off is the issue is a deduction and not fact , in my opinion

The term IMMO off would mean enable and not inhibit ( a reversal term of what my be happening )

Without looking at the video let us break down the starter circuit in parts

The BPM must provide a command ground discrete that goes through the on the transmission rotary switch

This ground path allows the starter relay to close allowing medium power to close the starter solenoid heavy battery cable power contacts for starter motor rotation

On the left side of the BPM are the 3 things that must be satisfied to allow the command ground on the Green / orange wire

Or remove the relay and add power to the 5 socket or white wire

The ignition switch must provide a ground through pin 1 to 5 to car frame ground

The decoder module is the RF transceiver on the key barrel that must agree with the key chip for a digital enable signal to the BPM ( not on USA vehicles )

Then you have the digital enable signal from the SLCU

To bypass this just provide the starter relay a command ground to close

Or you can swap it as it may be intermittent regardless of your battery disconnecting observations

The important observation is if the starter relay clicks 100 % of the time

And even if it does does not indicate if the internal power contacts are defective with burnt contacts not allowing proper current even though it would show voltage

As you are tinkering with the starter and draining the battery the engine ECU needs 11.4 volts for it to properly operate the fuel injectors

So watch the voltage sag on the instrument gauge as the starter can rotate well below this 11.4 volts

 

Thank you very much.

 

Ask questions and someone or myself can explain it another more clear ( or corrected ) way

 

Hi. After a couple of days when the car starts as I said (pull off the minus from the battery for 10 or 15 mins and then), I decide to replace the rear skock absorbers (left & right). After replacing it, the jag don't starts at all (don't crank), no matter how time I let the minus off the battery. After checking the SLCU, BPM, ECU, all the fuses and relays including the gas pump relay, the large conector on the gas tank, I didn't find any problem. I have also short the starter solenoid (relay in the front-left of the car), using an wire between the 4 and 5 pins and engine crank, but don't starts (of course, the engine didn't receive gas). I have to say that the gas tank is full and the crankshaft sensor is new.
If I know the security code, this may be useful to starts the engine ? Thank you very much.

 

After all of that years the solution is?

 

Describe your observations on yours as each case can be different

Year and what engine as the 3.2 and 4.0 with the slightly different transmission combo have a tiny bit difference on starter circuit ?

Do you get starter rotation ?

 

That was a response to a 6 year old thread....I don't believe there will be a follow-up to this.

 

im so glad to see that someone is here and I can share my pain, I have been a new owner for a year now of a 1995 jaguar xj300 4.0 sovereign that needed a lot of work.
It has been in the garage since the day I bought it and I have been doing repairs in my free time, mainly peripherals, not motors, with the result that it has run out of battery many times until I put an on-off switch on the battery so that it does not run continuously. The last work I did before it would not start again was to remove the rooftop with the alarm eyes (the car would drive normally without them). Until October 8, it starts normally. It had run out of battery and it never started again. I have read many forums but I have not been able to get it to work. I have a key and I also have an alarm remote control which only works to open the doors. Maybe this is another piece, another problem, so let me tell you what I've noticed so far: 1) i can hear the fuel pump 2) an error comes on in my air conditioning panel 3) it doesn't crank only if you make bypass on the relay
4)i check the key 🔑 if i have signal immo and they told me is veryy good and high signal
5) srs airbag light open when i turn the switch start
6) no check engine light open
7) i check and woth obd diagnostic and i have a fault code P1621.

i try a lot of things if you ask me i thought i have and another answers if i remember something else im coming back to write it.

sorry about my bad english , i really need a little help , thank you

 

I knew you would be back as a Jaguar X300 problem solver

I'll be back after wake up and be on station and operationally ready

Fresh meat

 

English is not England's best forte

Probably have a battery parasitic drain on battery coming from car side

Probably have the relays in the corners of the fuse boxes not closing

I'll run you through some easy test as I get ready for dialysis chair

As a new owner never install car battery in backwards , positive post fwd , never overtighten the battery positive post bolt

P01621 is an odd code that has alluded many and turns out to not be of issue

Airbag light will always come on during system start up so normal

The fuel pump will only come on for 3 seconds then off in starting sequence