Problem installing a new head unit in a 1994 Lexus ES300.?
I'm trying to install a Pioneer FH-S501BT in my Lexus ES300. The car also has a factory amp with all 8 (2 pairs in parallel) speakers wired to it. I want to keep the amp. So, I bought an adapter with RCA jacks on it that goes into the head unit. The factory harness connects to this adapter, then the adapter connects to the new head unit's harness and to the RCA jacks. The problem I'm having is that only two of the speakers work at a time. The other two make a buzzing/whining noise. Only the front pair of speaker wires were working. If I plugged the front speaker wires into the rear RCA jacks on the head unit, it would work. The rear wires from the factory harness aren't working. Anyone know why this is?