2003 f150 deck, 4, 4ch amp

Ok, we put 4 infinity ref 6x8 band new in this guys truck. 2 days ago we pulled his pioneer 1600 and rockford p4004 amp and rockford 6.5s out of his VW jetta. everything worked great. put it in his truck sound interferance like ground loop. turn radio down speakers humming. start truck bad alt whine. all signal wires seperated from power, tried a ground loop isolator and it made it sound like the music was under water horriable. tried re grounding amp same problem, took amp directly to batt. for ground same problem. ran new rcas down middle of truck just to check same problem. pulled amp bench test. slight humming of speakers. suspected amp bad. replaced w/infinity 4ch, same problem. swaped deck with bench pioneer, same problem, tried re grounding deck, and tried grounding rcas. same problem wth!! Please Help! Thanks in advance.D

MECP First Class Certified Installer.

Nothing is impossable, it's just more expensive.

Try swapping out the deck with a non pioneer, they are notorious for having bad grounds on their RCA's. Also try re-grounding the amp or at least taking a resistance check on the ground to make sure its ok, If the ground is bad it could cause the amp to ground through the RCA's causing not only whine but causing the RCA's to short out. Hope this helps. --->Richard2008 Scion xB

Pioneer AVIC-D3

RF 3Sixty.2 sound processor

Stock speakers (for now ;))

Thanks for the fast reply, it was the pioneer deck that was the problem. i swaped it with a kenwood and it worked just fine. Thanks again for the help. it is always good to learn something new.D

MECP First Class Certified Installer.

Nothing is impossable, it's just more expensive.