Been getting HDC inactive on start up recently if the car was left for more than a couple of days without being used (although it always let me select the HDC and the icon appeared on the dash as if it was working ok?).

Now today I got the trans fail safe prog error when put in drive from standstill the gearbox was shown in D but wouldn't pull away, just revved like it was in neutral.

I don't know how old the battery is but it's at least a year old. I did a battery test with multimeter and it was showing:
-12.2 v with engine off
-14v with engine on at idle
-13.85v with everything electrical switched on at idle

Do you think the battery is causing these errors or could I have a genuine gearbox fault?

By the way I switched off the car and started it up again and the gearbox was fine with no error messages (shifted as its supposed to in Drive/sport/manual 2003 Vogue 4.4 V8 Java Black

Having been thru all this it would seemthat ideally you want the bat to read 12.5v engine off and 14-4-6v at just over idle with everything on, I changed the bat and everything improved on mine but now going for alternator as I never see 14v with it running. Hope that helps, depending on mileage on the alt you could just put a new reg in it for £49. One day your life will flash before your eyes......................................make sure yours is worth watching!

HDC Inactive is the first sign of reduced battery power. it is possible but difficult to diagnose that the gearbox message is a result of the same problem, but unlikely once you have the engine running, as the alternator will/should be proviging the correct voltage @ 14.5V. Could just be a gremlin. Looking at fault codes might help, and could be gear linkage issues - have you greased your linkage recently....? .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Spilling Coffee/Drink on the gear-change area is also a good way to get HDC Inactive up.....

Right , mine is definetly only reading 14v with engine running, may have to look at a new alternator - does anyone know how much labour is involved in changing the alt? 2003 Vogue 4.4 V8 Java Black

Quote:

Spilling Coffee/Drink on the gear-change area is also a good way to get HDC Inactive up..... Whistle

NO food or drink allowed in my FFRR  .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

Quote:

may have to look at a new alternator

I wouldn't on mine (14.3v <- IIDtool)  .
Experience is the only genuine knowledge, but as time passes, I have forgotten more than I can remember
Volvo V70 P2 2006 2.4 Petrol 170bhp Estate SE
MG Midget Mk1 1962

Previous: L322 Range Rover TDV8 3.6 2008; L322 Range Rover TD6 3.0 2002; P38A Range Rover V8 1999

The 14v is prob not too bad the problem with mine is that on tickover as you switch everything on it dips quickly to 11.9v and rises to 13.8 - 12.9v like its spiking it, thats my theory and im fitting a new alternator next week. One day your life will flash before your eyes......................................make sure yours is worth watching!