The front interior light on my 90 was "flickering" and the rear light was out. I went to change the bulb on the rear light and got a spark at the bulb.

Immediately the fuse melted and some smoke came from behind the center console (at the time I thought it was from the fuse).

I put in about 3 fuses which all blew immediately. There are now some partially melted wires behind the center console and the radio has no power.

I don't even know where to start to look for the source of the electrical problem.

Any help would be greatly appreciated.

I recently changed the directional switch with a new switch from allmakes (although I am fairly certain this is unrelated and did not cause the problem).

Thank you, in advance.

There's a header behind the dash, above the fuse panel. Check that, and all your grounds.

I'd also look through the wiring diagrams, for where the light circuit meets the fuse panel.

I'll see if I can dig up something from the diagrams.

definitely worth checking earths first, they can cause all sorts of seemingly weird problems

Check the bulb is in properly I had a damaged rear interior light that was shorting the live feed to the roof blew the fuse all the time until light replaced