That's the good thing about forums, you always get differences of opinion and each individual can decide which advise and experience they want to go with...  Pete

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2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

I’m not interested in opinions when it comes to the possibility of frying my ECU - I want facts! 2012 TDV8 Vogue (L322)

Wow! Facts huh! There are many… I have been running my own Range Rover based workshops for 30+ yrs sir and it’s been widely understood, since the inception of the 322 jump starting RR’s is a no go! If you absolutely need to jump start a dead RR from this era forward, then corrected fix jump leads and let the one vehicle charge the other from 10-30 mins and then start it!
Anyone without any experience of jump starting should make 100% sure the jump leads are fitted correctly (following the procedures laid out in the owners manual) and then WAIT for the jump starting vehicle to charge the flat vehicle sufficiently!

Basically, would you get the power lead to your PC at home and pull it in and out of the power socket on the back? No, it would potentially blow things internally!

This is also the end result of ham fisted owners with no mechanical experience trying to jump start their 3.6 or 4.4 TDV8 from their daughters boyfriends Renault Clio using £4.99 Halfords jump leads…

And I place more emphasis on real life experience, that's the forum again, read all you can from others experience and knowledge and decide which way to go yourself, if you are happy to jump start then that is your choice, my choice would be to charge.....  Pete

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2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

All, crisis averted, it turned out to be a low battery. Car started first try this morning and I’ve taken it for a test drive.

Thanks for all the suggestions and credit to @JayGee for the spot.

It’s funny isn’t it that when you have a big, complicated, expensive car you tend to assume that problems will be big, complicated and expensive to fix.

Trying the simplest thing first is definitely the best strategy.

I have picked up an engine warning light in the process which I’ll need to get reset as I don’t have an IID tool. ( how a battery issue can cause this befuddles me but there you go ).

( P.S. the engine warning light cleared itself after a could of drives so all back to normal now. )

Anyhow, I’m off to put on my “dick of the day” tee shirt on which I shall humbly wear whilst I refit the sill covers and deploying side steps.

Thanks again to all.

FWIW; here’s how close she got to the garage wall:

Click image to enlarge

I know what will happen if I pull the lead from my PC - absolutely no harm whatsoever as the PSU and MB have built in surge protectors. I may loose some data but it won't fry anything. If I connect the booster pack or another car with the correct leads in the correct sequence what are the physical and electrical processes that can fry the ECU? 2012 TDV8 Vogue (L322)

I've heard jump start horror stories too. I carry my ctek mxs10 charger and 13pin tow electrics adaptor when I go on holiday etc Gone to a good home: 2011 4.4 TDV8 Vogue SE Buckingham Blue with Ivory and clear glass = "Rory"
2025MY Defender D350 90 in Silicon Silver on coils
1974 Series 3 Lightweight = "Millie"
Many, many other Landies over the years
My preferred specialist: www.glenrands.co.uk
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Glad to hear its sorted  Gone to a good home: 2011 4.4 TDV8 Vogue SE Buckingham Blue with Ivory and clear glass = "Rory"
2025MY Defender D350 90 in Silicon Silver on coils
1974 Series 3 Lightweight = "Millie"
Many, many other Landies over the years
My preferred specialist: www.glenrands.co.uk
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I've heard plenty of jump start issues when people use the wrong leads (insufficient current capacity) or connect in the wrong sequence and / or the wrong polarity. I'd like to hear of issues when the correct procedure is followed as this would indicate a major issue in the design of the charging system. I carry a booster pack but not a charger and am now seriously concerned I should be not using it if I get a flat battery. 2012 TDV8 Vogue (L322)

Jumped mine a few times, no worries about it at all, will continue to jump start if its needed in the future

Jump started hundreds of modern JLR products, never had an issue, when the correct procedure is followed

Its always safer to charge, but not always practical, and only a jumps start will suffice

And here we go again!

I tried… You can all do what you damned well please with your bloody jump leads! Jump packs n chargers! I’m out!

From the workshop manual...

Quote:

CAUTIONS:
A discharged battery condition may have been caused by an electrical short circuit. If this condition exists there will be an apparently live circuit on the vehicle even when all normal circuits are switched off. This can cause arcing when the jumper cables are connected.

While it is not recommended that the vehicle is jump started, it is recognized that this may occasionally be the only practical way to mobilize a vehicle. Prior to attempting a jump start, reference must be made to the Electrical Section of this manual - Jump Starting.

Following jump starting of a disabled vehicle, the discharged battery must be checked for serviceability and recharged off the vehicle as soon as possible to avoid permanent damage.

Do not rely on the generator to restore a discharged battery. For a generator to recharge a battery, it would take in excess of eight hours continuous driving with no additional loads placed on the battery.

Always make sure that the jumper cables are adequate for the task.
Always make sure that the slave battery is of the same voltage as the vehicle battery. The batteries must be connected in parallel.
Always make sure that switchable electric circuits are switched off before connecting jumper cables. This reduces the risk of arcing occurring when the final connection is made.