Well you see, I found this info out AFTER having spent a full Saturday the weekend before last, changing out my washer pump, cleaning out the filter on it, hunting down the fuses, getting drenched in washer fluid when I got my wife to try the washers and the headlight washers sprayed fluid everywhere in my garage like a fairground ride, scrambling around on my garage floor etc. etc. etc. then realised I needed to research the problem further. I couldn't for the life of me figure out why after cleaning out the connections and getting my wife to start the car and try the washers, the headlight washers were working perfectly on the first try, but then weren't working after that... that's when I found out that the headlight washers only fire every 4 times that you use the washer, ONLY if the headlights are on and ONLY if 10 minutes has passed since the last time they fired... I hate love this car!

 

I think that is a good explanation and the multiple causes are confusing.
Interesting that you mention CJB corruption? I have been trying to find out exactly what is failing in these CJB and software corruption would certainly explain it.
I don't know what an X-prog is? I have been hoping SDD could fix the problem and it looks like it can but only until the next battery disconnect.

Is the X-prog expensive?
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Yeah it seems to corrupt specifically the VIN number in the CJB, which then causes the car to recognise it as a CJB from another car, rather than one belonging to the actual car that simply has a corrupted VIN. This then causes modules not to talk to each other on the OBDThreeWan Kenobi (That's a joke for those who don't realise, it's actually the obdiii or OBD3) network properly and the only way around it, is to reprogram the Instrument Cluster in SDD (which understandably, sits in the middle of all the relevant modules on the network), this somehow ignores the CJB corruption and picks up the keys at the end by running the key verification and immobilisation procedures within SDD, restoring all functionality, except for the washer pump. Interestingly, only the windscreen washer pump is affected, the headlight washer pump still functions normally... oh and of course, the car will brick itself all over again next time you unplug the battery for any reason, because the corruption is still there in the CJB.

Unfortunately, despite the CJB getting corrupted and ending up with the wrong VIN number in it, just purely through a communication fault on the network during a battery disconnect, the only way to actually reprogram it to have the right VIN number in it again, is to 'virginize it' via an XProg (or similar) device, which is basically a little box that allows you to connect a laptop to the CJB and re-write silicon chips which are otherwise locked to writes from the outside world. In simple terms, it's impossible for SDD to rewrite the VIN number on a CJB (This is for anti-theft purposes, obviously), because it's just a cable, plugged into a laptop and doesn't have the right 'authorisation codes' at a hardware level, to rewrite the chip on the CJB. The XProg device has the 'authorisation codes' inside it at a hardware level, like a master skeleton key to a certain type of lock, to rewrite the chip used in the CJB.

The problem for non-techies, is that you need to solder wires from the XProg, to the PCB (Printed Circuit Board for the uninitiated) inside the CJB, then download the 'backup configuration' stored in the CJB's flash memory, then push that configuration back to the EProm Silicon Chip on the CJB. This restores the VIN number and original CJB Configuration on the chip and is the only way to access the chip without removing the chip from the CJB completely and using a proper cradle with the proper pin configuration to write to it. So it's not a task for the faint of heart. There's a company called Pelican Diagnostics who advertise through Ebay listings, who will do the job for you and charge you £180, plus the cost of sending it to them in the first place and they'll do it, within a 3 day turnaround, so you overnight it to them at your expense and pay the £180 on the ebay listing, they fix it the next day (Using an XProg device themselves) and send it back that day at no further cost, you get it back the day after... i.e. you send it on a Monday, you get it back on the Wednesday. There are also various trusted members on some of the other Jaguar Forums (Who I don't think I'm allowed to link to on here) who will do it for you for the cost of postage, you send it to them, they do it, then send it back at your expense, but obviously there's no guarantee of a 3 day turnaround, no guarantee they won't accidentally brick your CJB completely, no ebay buyer protection, etc. etc. I've opted to buy an XProg myself, as it's cheaper (About £50 for a Chinese copy) and I'll be able to use it multiple times if I need to (If some third party garage disconnects my battery without following the right procedure, or the terminal comes loose again, or I forget in my old age, because this car is never leaving me now, I've invested too much time and money in it for it to ever be sold), or if someone needs me to do it for them to their CJB, etc. I bought my Xprog off Ebay so that I have buyer protection if it doesn't work, but you can buy them at varying prices online. The original inventor of the device charges over £1k for the device and the software...

 

OK thank you for the detailed explanation! I understand a bit better and it is a software corruption issue.
Yes I looked up the X-Prog and see that at the chip level many things can be done that SDD will never be able to do because of hardware and software limitations purposely built in like you said because of anti-theft reasons.

I have and use the SDD but upping my game to include X-Prog will require more steps and time to learn.
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