850 Volvo dashboard lights wont work.

Sounds like it might be fully in park. Move the shifter around a bit then make sure it is fully in either park or neutral.

your key switch is defective the code reader circuit in your igniton switch cylinder is wearing out

This sounds like a gearbox issue. Take it to a garage with diagnostic equipment and get the fault codes read.

Rob

this indicates an automatic gearbox problem associated with the winter mode switch
does your car drive ok or are you stuck in ultra low gear with a max speed of about 10mph??

I AM A VOLVO MASTER TECH AND YES IT IS THE DIMMER SWITCH CIRCUIT

yeah the main ashtray light and stereo light fuses are normally located in the cab of the car under the dashboard you should also find that the interior light is not working as this is part of the same link. these fuse boxes can be in some obscure places such as the pillar which is only only visible while the door is open, or under the acctual dashboard.

There is a dimmer for the dashboard lights on the dash. Make sure it is up. If all the other warning lights come on on the dash as well, then your ignition switch needs replaced.

My first thoughts are with the battery cables, or the alternator. You probably had the heater, wiper and maybe the lights on? That's a big load on the electrical system. Have the battery and charging system checked out! It's common on this model for the alternator brushes to wear out and the good thing is that they can be replaced separately of the alternator.

take positive side off battery for 15 minutes should reset computer