Working on a 2004 TD6.
When i got the car it would not start on its own powersource.
Changed battery, changed alternator(faulty), changed starter... No difference.
It could seem like its out of power when turning key, and it probably is. When using jump start cables from another RR it start with out problem, but disconecting startcables and trying to start its the same thing, just clicking in the starter, and its out of power again. When running, everything is working, charge 14,4, all lights, EAS and everything else ok..

Any ideas?

Sorry for the english.. In the middle of the night in Norway and a bit tired/frustrated.. Haavard Norheim

Hi... Have you used a meter to check the -ve from the battery to the chassis? I once had a cracked lead. When you use the jump cables, I take it you use the +ve jump stud and not the +ve terminal on the battery. I am wondering if there is a problem with the cable/connection going from the battery to the stud? You could prove this by puting the jump lead directly onto the battery and "hopefully" it will not start either...  Previously..
Vogue SE TD6
Defender 90 2.4
Defender 110 TD5
Vogue 3.5 EFI

Found the fault!

I changed the battery first. New installed.. When it still dischaged, i checked the alternator and found out that some A..hole on the stealership my customer had used disconnected the plug on it to "solve" the problem with the batterylamp. I connected it and the batterylamp would not go out. Changed alternator and lamp turned back to normal, and charging 14,4v. Thought that solved it, but after driving the car several miles it would still not start.. Changed starter and found out that also this had seen its best days.. Still no luck..

Started it with cables again and connected a voltmeter and took it for a drive. Charged 14,2-14,4 and no problems. Stopped it, and in 2 sec, voltage was down to 9,2v... The alternator had killed the new battery also!!
Installed yet a new battery and that solved it.. Starting fine now and lesson learned.. Haavard Norheim