Hi,

gave somebody a jump start yesterday and this morning when starting up, I got the trans failsage prog message come up and the flashing low-range dash light.

Turned off and back on again and it's fine.

Ignition off with a voltmeter gives me 12v and on idle 14.02v

It's a FF 4.4 2004 Vogue with LPG conv.

Cheers

Jump start and then restarting probably dropped the battery voltage a tad too much.
Battery could have been recovering voltage by the time you started second time.
I would just see how it goes, chances are not much wrong.
The alternator voltage at 14.02V on idle is ok, the battery voltage should be measured after any door has been closed and the car has gone to sleep. About 20minutes.
After a run the battery voltage should be about 12.7+V and then gradually decay over a couple of days to about 12.6V.
Cold weather reduces the battery voltage a bit, about 0.1 to 0.15 V depending on temperature.
If you do measure 12.0V after the car has gone to sleep the chances are your battery needs replaced, be worth getting it tested.

Cheers NiceDayForIt

I'll check it in the morning.... will open the locks and then leave it open for 20 mins before checking voltage!

I think it's on it's way out - cranking on a cold day takes a bit longer, ODB2 port isn't working (that could be something else) and I have an air suspension fault too that needs clearing down. I've been told that battery issues manifest themselves usually with air suspension first? Not sure how true that is!

For what it's worth I find the easiest way to check the battery and alternator voltages is to use a plug-in voltmeter in the front cigarette socket. Assuming this socket is permanently live in your car.
If you plug the voltmeter in and then lock the car and leave for 20minutes you can then read the battery voltage by looking in thro the passenger side window.
For the alternator voltage just leave the voltmeter in position whilst driving and you can observe the alternator voltage fluctuating on it.

Something like this is reasonably accurate,

http://www.ebay.co.uk/itm/Ring-Automotive-...43b7454a11

IID tool is great too if you have one as it displays live values as your driving.  Present :2008 TDV8 HSE
Gone Audi A5 2.7TDI
Gone Discovery 3 HSE
Gone Mercedes CLK
Gone Range Rover 2.5 DSE