Good morning .....this problem occured long ago with the fuel gauge not working on my 02 v70 XC.afterwards my dash cluster went out and I just got around to fixing it.now that everything else is working, I can confidently say the cluster has nothing to do with the issue of the fuel gauge.I am experiencing a dead gauge almost always.in the beginning it did a few different things- such as the needle only going to the red zone ( with low fuel warning light) this would occur in position 2 of ignition switch and after startup, also while driving from dead to same reading mentioned( in red w light illuminated) .One thing to mention is upon firing up new dash cluster, it briefly exhibited same behaviour briefly ( needle from dead to red w light) then right back to showing no fuel.i will say originally all at once the gas gauge rear door locks the tailgate lock and gas door lock control all went out! I have read it may be the rear module .if it is I eventually can send the module out but I am looking to test my way to this affirmation.in addition I am looking to get the gauge working independently if possible! Thanks in advance.any ideas are welcome as long as it's safe!

 

first thing I'd do is check fuses, then I'd test the sending unit (the float in the tank). You should find some vids on Youtube on how to test using a multimeter.