I have a 2007 XL 2.2 Manual and it has developed for the third time in 5 years, an electrical fault relating to the Can Bus.
The fault is that the Heater blower stops working, The radio & Clock Stop working, The electric gate to 5th & 6th gears doesn't work, The central locking wont work and the lights when on Auto, stay on all the time. Just remembered, the parking sensors also don't work.
I have found that if I plug my cheap OBDII reader into the socket Everything works !! When I unplug the faults come back !
I have shelled out £1250 for my local dealer to try and find it, but it still happens ----- Any Ideas Please ??

Might be that if one of the terminating resistors on the CAN has an issue then connecting your reader might correct it temporarily.

With all powered off measure the resistance between OBDII pins 6 to 14, it should be 60 ohms.

Many thanks for the response -- If it ever stops raining I'll get out and give it a go and report back !

Well, Have checked the Resistance between the Can High & Can Low ( pins 6 & 14) and I get 63 Ohms --I guess given my multi-meter is un-calibrated and if resistors have a 5% tolerance -then it's about right !
Back to the drawing board !!!

We in the jaguar community know that our vehicles are very susceptible to minor voltage variations.
To such an extent that many use battery maintainers... so I have to ask, are you certain your battery is fully charged? And is it healthy?

I am in the habit of changing batteries every 4 years as older batteries just don’t measure up. Guy Pensa
Cars with Personalities
Getting itchy. What's next?
2014 Land Rover HSE Lux (blend of practicality and aggressiveness)
2007 XKR (Jaguar Racing Green) (woo hoo!)
2004 XJR (Jaguar Racing Green) (deceased)
2002 S-Type R (British Racing Green, of course)
1951 Riley RMD (Black, time for that restoration)

Hi Guy,

Thanks for that -- However, I thought the same could be true, so after the garage couldn't fix it, I decided to fit a new battery as the old one was about 5 years old --- Nice shiny new Battery is just 3 weeks old !!

Understood, but are you aware new batteries from the shelf are rarely fully charged?
I would have it on a charger for 24 hours.

There are strange gremlins able to creep out if the voltages aren’t quite right. Guy Pensa
Cars with Personalities
Getting itchy. What's next?
2014 Land Rover HSE Lux (blend of practicality and aggressiveness)
2007 XKR (Jaguar Racing Green) (woo hoo!)
2004 XJR (Jaguar Racing Green) (deceased)
2002 S-Type R (British Racing Green, of course)
1951 Riley RMD (Black, time for that restoration)

Hi Again Guy, Yep, was aware of that and did give it a top up --maybe not 24 hours, but at least 16, so I figure it was as good as it would be in day to day use.

Jeepers. Bad ground somewhere?? Sorry. Guy Pensa
Cars with Personalities
Getting itchy. What's next?
2014 Land Rover HSE Lux (blend of practicality and aggressiveness)
2007 XKR (Jaguar Racing Green) (woo hoo!)
2004 XJR (Jaguar Racing Green) (deceased)
2002 S-Type R (British Racing Green, of course)
1951 Riley RMD (Black, time for that restoration)

http://www.freel2.com/gallery/albums/userp...Socket.pdf

Although in theory the Bus system doesn't require an earth, in practice it works better if units are connected by a 'signal' earth.

Although I cant think how the OBD supplying this signal earth can really correct all these faults.

Do the DTC errors give you a clue as to which is the primary offending control unit? FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)

Hi Ian ?
The OBDII reader shows NO fault codes !!! Now, I do realise that it is a very cheap thing I got on eBay to turn off a service light on "Her" old MGF ( which it did. The reason I found that it all worked when plugged in was because they told me at the Garage that when they plugged their proper and very expensive OBD into it, the fault went away --so I thought I would try it and it worked. To my simple mind, it must be somehow by-passing whatever the fault is ( broken wire, cracked component , you tell me,
I have just found another strange thing --- When all is working OK I can move the electric seats without the Key inserted -- When the fault is there, I can't But it will move once the engine is running even without the OBDII bodge plugged in !!!

So, you have no idea what the fault code was/is because once the the OBDII reader is actively plugged in/communicating at the port, no fault code remains on dash? Is it a check engine light or a fault on the digital display?

Hi ! I have No fault lights or messages on the dash or the OBDII reader -- The faults I have are those in my original first post and followed by the one later with the electric seat

That very weird & difficult to trouble shoot. Here is a cheap temporary solution until you can track this issue down and solve it. Buy a cheap on/off switch for the OBDII to your reader and turn it on before starting the vehicle, off when you switch off the vehicle as the reader will pose a small draw on the battery when connected. Velcro your reader to the dashboard.

16 Pin M to F with Switch OBD2 Cord Extension Cable Adapter Connector On/Off

Amazon sells them quite cheap.

I've had a quick look but I can't see an obvious wiring link to cover all your symptoms.

I suggest that you have a really detailed look at what is working and what is not with Reader connected/disconnected, and ignition on/off.

This includes doors, interior lights, and all accessories.

In the meantime have you seen these posts of wiring diagrams and earthing points.

Find the Earth Distribution diagram, Diagnostic Socket Power Ground (pin5) goes to Common Earthing Point G3D134-1,
and Diagnostic Socket Signal Earth (pin4) goes to G6D139-1.

https://www.freel2.com/forum/topic2943.html

https://www.freel2.com/gallery/albums/user...TS_LHD.pdf

https://www.freel2.com/forum/topic32832.html?highlight=earthing FL2 XS SD4 Auto 2010 2012-2017 (21k - 91k miles) (MY2011)
FL2 Metropolis SD4 Auto 2014 2017- (16k - 77k+ miles) (MY2015)
Metro in its 11th Year of (Extended) LR Warranty / Full LR Service History
(Expensive, but Trouble/Worry free - hopefully?)