Well I just picked up an 02 wrx a few days ago.
when I bought it the speedo wasn't working and it was throwing a p0500 cel. I replaced the speed sensor and also traced it to a broken wire form the ECU because this tard tapped the speed sensor wire for an HKS turbo timer type-1 (I soldered it back together). Needless to say I was still having a serious issue. The backup lights worked for all of 2 seconds one day then blew the fuse, as soon as the backup light fuse blows my speedo goes to 0 MPH and wont move as well as MY headlights wont work and If I try to turn on the headlights with the blown backup light fuse the ABS light goes on and the headlights don't even come on (the daytime running stay on though)... and then the ECU spits out a p0500 cell again!!??!! So I replaced the backup light fuse again and all of a sudden I have a working speedo/headlights/abs again!!??!! So today I went for a long 200 mile drive and all was working good until I was about to head home, after switching into gear (2nd or 3rd I think) the backup light fuse blew again and poof no speedo/headlights/ABS. I replaced the fuse and turned on the car and it blew again I did this 2 more times, then I put the car into reverse a few times and put it through the gears with the car off and replaced the fuse. After that the fuse was fine and I have a speedo and whatnot again!!??!! With the fuse in I do not have backup lights though and this is whats throwing me off, and if I remove the fuse the speedo and everything else mentioned die. From what I can tell is the backup light is completing a circuit but for more then just the backup light.
I am stumped right now can anyone give me some incite without saying take it to a mechanic... cuz thats not helpful