Keyless entry no longer working on 2001 XJ8

[dhammond]

Vehicle is a 2001 4.0L XJ8 SWB. The keyless entry has suddenly
stopped working. Central locking is still working and engine still
starts (so key transponder is working). Have replaced battery in
keyfob. Keyfob tried on Sealey keyfob tester which shows that
keyfob is transmitting.

Have tried reprogramming the system to
accept the keyfob without success (using the headlight switch
method of entering programming mode). No beeps whilst pressing keyfobs. Only two beeps at end of programming cycle.

Where is the receiver / aerial located? Is the receiver separate
from the alarm module? Has anyone else experienced the same
problem and has found a cure? I am wondering whether it is
something as simple as a fractured wire or a loose connector (roads
are getting quite bumpy where I live) but without knowing the
location of the modules or a pinout of the relevant connectors I
cannot test this.

I am assuming that if I get another security and locking control
module from a scrapyard that it would need a main dealer (or
someone with specialist equipment) to configure it to work with the
car as I assume that the modules are coded.

If I was to fit an aftermarket Thatcham CAT1 alarm would the
installers be able to disable the Jaguar system? I would guess
that this could be cheaper than paying a Jaguar deal to fix this
fault.

Regards,

David

[daveji]

Try the reprogramming method that worked for me.
Open the boot with the key.
Turn on the ignition (do not engage the starter)
Wait for the self test lamps to go out.
press the "VALET" button 5 times within 5 seconds
then press any button on the remote.
It should then work (don't forget to shut the boot lid first)
You may need to reprogramme any other fobs you may have as well.
Failing that a dealer with WDS can reprogramme your keyfobs for you.

[dhammond]

I believe that the valet button method only works on the earlier models when the valet button was a rocker switch under the centre armrest.

The method for the later X308 models is as follows when programming a single transmitter:

Hold headlamp flasher switch in the ON position and turn ignition switch to position I (first position)

Flash headlamps four times and the system will enter alarm programming mode which is confirmed by the security light on the gear shift flashing.

Press either the lock or unlock button on the keyfob and the alarm will chirp a confirmation when the button is pressed.

The alarm must complete a full cycle of programming of transmitters five times so when there is only on transmitter then this needs to be programmed five times.

This has worked in the past on this car but is not working this time. During the programming cycle the alarm does not give a chirp when the transmitter button is pressed. It only gives two chirps at the end (I do not know if this is an error signal as I cannot find anything that gives details on fault finding the alarm system).

Is there any way of getting the alarm into a diagnostics mode to be able to fault find it without the use of Jaguars own diagnostic equipment? I have engine diagnostic equipment (AutoXray and a ELM327 system) but nothing for testing the other systems (at least not without specific software or details of the expected codes).

I know that a number of aftermarket CAT1 alarms had routines that could be accessed by the installer to check the system.

I am assuming that the problem is either due to a fractured wire or a loose connector somewhere between the receiver and the security module or a fault with the security module itself. I believe that the alarm aerial itself is part of the rear window (top section).

When the transmitter button is pressed is the signal routed directly to the security module or is it received by something else and then transmitted via the CANbus line. If I knew how the system interconnects I could connect an oscilloscope to it to aid in fault finding. Similary if I knew the routing of the receiver circuit I could check the resistance of the wiring from the aerial to the module to determine if it is a fractured wire (I have known X308s suffer from fractured wires in the boot section between the multiway plug above the fuel tank and the destination module).

As the central locking is still working and the key transponder system is operating (alarm is disarmed by inserting key and rotating to position I) so I am assuming that at least part of the security module is working and the signal bus between the interconnected modules is working.

I am assuming that since the X308 is so reliant on communication buses between modules that it is not possible to replace the security module with an aftermarket system.

Regards,

David

[atlegranby]

Hi
I got the same problem on my -99 x308. I tryed several keyfobs, and I even tryed to change the security module (a used on from e-bay). And I got a individual Jaguar garage to try to reprograme the fobs on both security modules without luck .
The security module is located in the boot, under the fusebox, and the antenna is mounted in the top of the rear window. They are connected with a standard coaxial cable.
On my car there is no faults in the antenna system, but I expect the security module to be faulty......?????

Anyone know the price on this one?

I am realy eager to get som innput on this topic!

[dhammond]

Vehicle has now deteriorated further. Now the immobiliser is not disengaging. Unlocked car this morning using the key, no chirping occurred when I opened the door and when I put the key in the ignition the engine would not start. LED on transmission was flashing throughout. Tried locking and unlocking the car again but car still would not start. I believe that the key reader linked to the immobiliser is a separate system to the wireless remote.

What is the common system that could be causing this problem?

Could the body processor module (BPM) cause this?

If it was the BPM, could a second hand one be fitted and then reprogrammed to the car?

Any suggestions gratefully received.

Regards,

David

[joejag308]

David, it sounds a complex issue one for the experts i would say....drop Dave Marks a detailed e mail re your problem, they are annoying when you cant just put your finger on the problem, but fishing around could make them costly too...........Joe

[dhammond]

Update:

Disconnecting and reconnecting the battery has solved the immobiliser problem. Note: When disconnecting the battery on a XJ8 you must leave it disconnected for at least 30 seconds before reconnecting.

Now the boot can only be opened using a key (button on dashboard and on boot does not work now).

Everything seems to be pointing towards the BPM.

Regards,

David

[joejag308]

David that seems to have simplyfied the matter somewhat, try the options above with the keyfob, i know Admin has done this, its not that much trouble to take the battery leads off and charge the battery up either to get the result you want.........complicated things these batteries at times............must be female...... Joe

[dhammond]

Fault tracked to the Security and Locking Control Module (SLCM) after managing to get access to a XJ8 electrical wiring guide.

Car going to Jaguar dealers tonight for them to plug in the Portable Diagnostic Unit (PDU) into the vehicle to determine which version of the SLCM needs to be ordered (giving the number printed on the module and the vehicles VIN number is not sufficient to be able to order a replacement part).

Regards,

David

[joejag308]

David at least you tried to do the simple things first, but in the end if that doesnt work the only way to go is with the people who have the correct equipment, we have to realise we do own a complex piece of kit and the wrong things done by people who dont know what they are doing or dont have the equipment to do it could cost YOU a lot of money.....at least the job will be done with no recurrence hopefully.........good move ...Joe

[atlegranby]

Hi
As I told you before I got a similar problem on my car. I tried to solve the problen on a Jaguar garage with Autologic diagnose system, but he did not find the fault. So I tried my best to solve the problem my self, and after a lot of thinking I came to the conclusion that it must be the security locking module (in the boot). So I went to e-bay an got myself a used one for £35.
Presto: Problem solved:-)

I am a happy bunny!!!!