Part # for Neutral/Stop software patch
 

After many requests, have made this a sticky.
This applies to AW55/50 auto transmisson boxes, and their variants, mainly applies to model years 1999 to 2002, check your VIN with Volvo.
This prevents the car automatically seeking neutral while waiting in 1st at traffic lights or in jams, the patch prevents the big thump and consequent wear when pulling away from stationary while the transmission is in "D".

The Volvo Part number that you should ask for is:-
Neutral control by software = 30646691
TCM software upgrade = 30677036

Prices as at August 2010 were
30646691 = £9.11p
30677036 = £14.20

All + VAT

Will this cure slipping between second and third gears? This has happened immediately after adaptation & fluid counter reset.

No, this just fixes the bang when pulling away after an idleing stop.
Your issue sounds like sticky valave body poppets.

Your a star nick!!!!!

Kastner is going to have a shock on Tuesday!!

Will I have to order the part numbers over the phone or just when I arrive with the car??

What's the best cure for the sticky valve body apart from replacing it!!

There is a thread on here somewhere (from 2012) that details how to remove the valves, take them to bits to clean them out then rebuild them and replace them back in to the autobox, fiddly is what it looks like but certainly worth a shot, or you can purchase replacement valves and fit them - Mike

Look at This Thread for solenoid cleaning information - Mike

I would always try the TCM upgrade software and new oil before taking anything apart ...

I agree with Clan, check gearbox oils etc first.

Neutral stop is nice to have and it evidently worked at some point, so something has worn or gone out of spec. I suspect one of the gearbox valves has gunged up and is moving too slowly, but I have never opened one of these.

In older automatic cars (e.g. my old Sunbeam Rapier) we could empty the gearbox/torque converter oil and then run new flushing oil through the gearbox for a couple of miles and drain it and refill with the right stuff, but I am not sure we would get away with that on one of these boxes?

Mine (V70) improved as soon as I changed the gearbox oil but it's slowly gone back to thumping again since then.

Just a word of warning regarding prices for the updates. There are the "part" prices as mentioned originally but my local Volvo dealer has quoted that price plus an hour's labour for the workshop time as well. £45/hour.
Just to bear in mind.