i have a 99 civic cx....what is the best way to find a short circuit? i have a short circuit in the alternator/sp sensor under da dash fuse box...everytime i put a new fuse in and turn the key to on postition...the fuse blows..ever since that started ..my speedometer doesnt work...in case it was the alternator ..i replaced it already...??

 

Well you'll need to follow the wire after the fuse, since the fuse is blowing, it means the short is after the fuse. You may need to take out the guage cluster and possibly need to drop the steering column to follow it.

 

Dahm your in for a fun job!

 

that fuse powers;

blk/wht wire to the ELD unit
blk/wht wire to gauge cluster (alt light)
blk/wht wire to EVAP bypass valve
blk/wht wire to EVAP canister vent shut
blk/yel wire to EVAP purge control solinoid
blk/yel wire to VSS - without power this will not tell the cluster how fast you are going, hence your speedo problem.
blk/yel wire to primary O2 heater
blk/yel wire to secondary O2 heater
blk/yel wire to alternator

I'd disconnect each and every one of the sensors, check for shorts in the sensors and harness, and go from there.
good luck man.