I recently bought a 1996 dodge ram with an infinity sound system, it had an aftermarket head unit in it and all the speakers worked, i replaced the harness and put a new head unit in and the driver side front and rear speakers do not work anymore but the passenger side does, i have checked the harness multiple times. What could it be?

 

Have you checked to make sure new head unit doesn't have a bad channel? Have you tried the balance?

Dave