XC70 - rear electrics failing

[Guest]

Hello, from the 'newbie'.

I bought a used XC70 SE. Like night follows day, as soon as the warranty ran out the electrics in the rear end of the car started to fail.

About 3 weeks ago the sat nav started to read 'cannot read CD rom - please re-insert discs'. Which didnt help.

Last week the boot refused to unlock. Starting the ignition and playing with the lock button cured it. The 'Bulb position light failure' warning light diapeared, even tho the bulb was still out.

On Saturday, the rear door locks refused to stay locked and the fuel guage started to read empty. A trip to the gas station revealed that it was 3/4 full.

On the way to the Volvo garage today, I noticed that the rear wash / wipe had stopped working, and on collecting the car the dealership was told that the rear fog lamp, and the back up / reverse light were also US. With the lamps 'switched on' no lights come on, and no error messages appear.

I guess its a common earth problem, a common live problem, a relay problem, broken wire / loose connector or an electronic module fault. In the good old days I would have looked for the shop manual and sorted it in 15 minutes. But this car has more wires than an F15.
FYI, the dealers diag machine has gone west.

Any help would be much appreciated.