Ohk this is the deal chances are the channel (L) is bad if you want to verify instead of switching a whole bunch of stuff start simple check the subs on one channel (L) then the (R) which ever channel is having the problem mark then take a 2 female 1 male splitter hook it up to the good channel if that doesnt solve your problem then its at the head unit which could be as simple as a bad connection. Good luck.. Remember check every connection...

 

i had the same problem, but i installed an output converter, and the popping quit

heres a link to the one i used

http://www.bestbuy.com/site/Scosche+...=1218106684939

its cheaper at walmart

 

Did you do all the unpluggin and fartin around while there stereo way playing. That could be a factor. Did you check the fuses? Could have blown a channel when the power wire was clipped.

Good Luck!