Mystery fault, and I'm not really sure where to start looking.

I noticed that the dash lights were not working and subsequently discovered that tail-lights were out also. Found blown fuse in engine bay fuse box, replaced, blew again, repeat.

I'm not sure where to start looking. I haven't carried out any recent work ...... apart from swapping stereo. Could the fault be related? Stereo is working fine.

Any advice appreciated. Hate electrical faults!!!!!

what have you got there a 4cy or V6


under the engine bay fuses is one wire used to carry the load of all the light and dash and rear tail lights-- the wire feeding into where the fuse keeps blowing
battery terminals off .
My solution was to spit that wire and run it through two fuses..its not a solid but a stranded
I got a spare fuse and base off a wreck and it slots right in... next to the original -you undo the fuse box from the chassis and work from under the fuses holder - insulate wires as you go
so the power load is then shared between two fuses .... works a treat

dont stuff up pinch cut or earth out wires as you refit that fuse box

HINT the stereo you fitted needs an extra earth wire added to its body to a chassis earth
.
V6 and 4cyl engine bay fuse box will be different
http://i253.photobucket.com/albums/hh59/magnabuff/Mitsubishi/magnafuse.jpg (http://s253.photobucket.com/user/magnabuff/media/Mitsubishi/magnafuse.jpg.html)

i've found that the wiring loom can ever so slightly rub on the metal sub frame behind the stereo on these second gens. first one i had to diagnose had me going for a while (not shorting unless turning left). the best way to diagnose a short is to take a blown fuse and solder two long wires to the terminals, then wire a headlight globe across those wires. This gives you a strong glow to indicate that there is a short and at the same time limits the current draw to ~10A.
just be careful where you place the globe because it will get hot. (or use a sealed beam)