Is there a particular module/relay that is common to the horn, keyless entry, trunk release and perhaps windows? Reason I ask is that none of these items work with the exception of the passenger window which works fine sometimes then quits then works then quits for no apparent reason...........all fuses are checked and good. Any ideas??
i had almost the same identical problem you may need eith the rear integration module or the BCM neither is cheap and they must be programmed by the dealer.
to know for sure what you need no code scanner other than a TECH 2 can read those codes. going to a dealer and paying the hour for the testing would be your best bet for mine it was $90 depending on where you are located. if you are around NH i could get it done for ya a lil cheaper and may have the parts locally available (used and much cheaper).
2005 Pontiac Bonneville GXP
2008 Chevy Impala 3LT 3.9L (9C3)
2000 SSXP (retired) all over the country in a million pieces