ground loop problem... cant fix it
ok, i have searched... and read a lot in an attempt to fix.
i have a pioneer head unit, and a mtx amp for the sub, and a sony for the speakers. everything sounds awsome with the truck off. but when you start it up... well you can hear the fuel pump, and there is MAD sound tach.
i have pluged the rcas into my ipod, and it plays great with the truck running, no noise or anything. both amps have 2awg to the frame. and 4awg from the batt. the batt is an optima redtop so it has the top posts, and side posts. i put a 2awg from the side post to the frame. and the top post ground goes to the body with about 12awg, and to the block with 2awg. all the grounds on the body, frame, and ground bolts i just cleaned with a wire brush with my grinder.
no here is how the head unit is wired. i have an aux fuse box which i have some aux lights wired in and that kinda thing... it has 8awg to the batt. my stock fues box has about 10awg, and the starter is 2awg. this is all on the top post, and both amps are hooked to the side terminal on the batt. (the top + post cable has all thoes cables molded into the connecter like this link! )
so the deck is wired to the Aux fuse box with 12awg wire and it is switched on with a toggle and the toggle gets its power from the same 12v line. then it grounds to the body in the cab. now im 90% sure that the ground problem is at the deck.
i tried hooking some jumper cables to the ground post on the batt and un hooking the decks ground from the body, and clamping the jumper cable to the decks ground, and the chasses of the deck. it made it a bit quieter but not much. i also tried my older deck and it too had sound tach, and fuel pump noise.
i get the noise in both amps. all my speakers are amp powered. when i play my ipod threw the rcas it sounds good.
how do i get rid of the noise? im out of ideas... so i guess im gunna buy a ground loop isolater. and see what that does. any ideas?