Originally Posted by travis398
Hey everybody. I've run into a problem and i'm seeking advice. I have a 1993 Ford F-150 and i have recently put in a 400 watt amp and replaced all 4 speakers. The rear speakers i ran cable directly from speaker to amp. The front two speakers, however, i'm not sure of. I used the factory cable from the door to the CD player, then ran my own cable from there to the amp. But when i did this, i found that i had to have both the speakers on one channel for them both to work. When each speaker was on its own channel, only the left speaker would work. is there a wiring harness between the door and the dash that i missed? Thanks.
Sounds like the output amp for the dead channel has gone south, or the harness has broken.
Use a Test speaker, and hook it up one channel at a time, If one is dead, and the harness is good, you have lost an output Brick, Or thermal limiter for the brick (Comes from running on an open speaker line.)
Repair or replace the amp as needed.