I have a 1990 300E 2.6L engine and both rear speakers are not working. I had the original Becker radio and the rear speakers were not working even though the fader switch in the center console seemed to work. When thw switch was in the middle position or the rear position, the speakers don't work.

I thought it was the head unit so I replaced it with a JVC radio with four outputs for speakers. I used a wire conversion kit and wired the speakers directly and by passed the center console fader switch. The rear speakers still don't work. I haven't pulled out the speakers to test them but it seems odd that both rear speakers would be blown.

Any recommendations on what the probelm may be? Thanks.