im working on installing an fm modulator with an audio input and a pre-amp so that i can listen to mp3s etc thru the factory head unit, everything was working fine when i tested it yesterday for about a minute, but now nothing works on the radio at all, not even anti-theft flashing led, so I put a meter to the 12 volt switched power feed coming into the radio and nada

checked the accessory fuse (7 1/2 amp) its good and the empty fuse slot reads 12 volts which means somewhere between the fuse box and the end of the wiring harness there is a problem

is there a relay i can check? is the ignition switch wired to another location with easy access? etc etc

this is so weird, thanks in advance

 

ok, well no replies yet hmm.....

after further checks today, i see that the 12 volts out of the accessory fuse slot is already switched, i.e. its off when no key in ignition....which tells me the output from the accessory fuse should go directly to the accessories themselves (radio, cig lighter) with no further components in between, is this correct??

i also noted that on the inside of the fuse cover, the specific label for this 7.5 amp fuse is "acc relay" on the sticker, which tells me there is a relay somewhere to check but I don't know where it is...then again, as I mentioned above, the relay is part of the switching process, and the fuse output is already properly switched on/off by the key, so I doubt that my problem is anything other than a shorted out wire...which I have no clue how that could have happened out of the blue

does anyone have a schematic of the fuse box, im trying to find the wire that comes out of the box, from the 7.5 amp accessory fuse, i checked continuity on the 30+ wires exiting the box on both sides and almost all of them have continuity to the empty 7.5 amp slot??

help