The speakers in my rear door dont work at all not even a thud when the ignition is turned on. Having done a search I am still non the wiser, it is the original radio in my 1995 V8 so can discount an after market head. I have checked the main plug into the amp and have got power on the pinkish wire, other than that I'm stumped. Is it common for the amps to fail ? Is this the most likely thing? Thanks.