That is a bit odd. I would expect all lights to either come on, or none at all. What year is your car?

It's a V40 sport estate, '04 reg
Everything was working fine for a while after i got it. It just decided one morning to stop working altogether. Unfortunately, of course, i can't get the boot open as the lock appears to have been changed at some point and the key doesn't fit.
Volvo released the fuel filler flap for me though, but weren't much help otherwise. I'm not paying £500 for labour plus parts to fix this issue. Any other info you could give me would be a great help.
My next step is to check the rest of the locks, including the bonnet (which i may just change anyway) Unless you can suggest anything else.

Thanks for your time, it's much appreciated

Silly thing, but can you check if both connectors on the driver's door switch are connected properly?

http://i157.photobucket.com/albums/t...vo%20V40/4.jpg

Already have, it's been off and on a couple of times now. I had the door card off yesterday and changed the microswitch in the lock to see if that was the issue, still nothing.

I was going to suggest the microswitch in the drivers lock, but you've checked it already...... Don't think there is a point checking the rest of the locks as I doubt they have anything to do with your problem.

Which leaves two possible causes. Either the lock alarm unit it fried, or there is a ground sorting somewhere.

I swapped out the control unit with a second hand part, still no response so i swapped it back. The bonnet lock does not appear to have any connection to the system apart from the pull cable and there was a small bit of broken plastic floating around when i removed the mechanism. I have a replacement lock on it's way, maybe that'll help. We shall see.

I've now changed the bonnet lock for one with a microswitch and plugged it in. Still no response from the central locking, either from the fob or from the switched inside.
I'm at a loss now, i've swapped the control unit, rc receiver, bonnet lock, drivers side micro switch, sensor on dashboard and still nothing.
If you've any other ideas, it would be much appreciated.

what does your wiring loom look like underneath the radiator? if could be worn and causing these problems.

there is a guide on here on how to do the wiring loom

Last two things to look at would be the siren under the OSF wing and then the loom under the radiator and under the OSF wing.

I am wondering if reading the VGLA codes with DICE would shed any light

that would have been the 2nd or 3rd thing i would have done (maybe called you 1st though)