Honda rear speakers no sound

Make sure none of the speaker wires have exposed parts touching the chassis of the vehicle.  Also make sure the positive and negatives don't touch either.  Usually head units (stock or aftermarket) will go into a protection mode whenever a speaker short is sensed.  They do not shut down the unit itself but the amplification is shut down until the short is fixed.  Some systems will isolate the front channels and the rear channels--this may be the case in your situation.  One of the rear speakers is shorting out, so the head unit kills the power to both rear speakers, but you'll still hear the front channels.

Usually I''d start by looking at the underside of the rear speakers  (if possible) and at the positive and negative terminals on each speaker.  Make sure they're not smushed up against the metal surfaces where they're mounted.  If the back ones look okay, it may be something with the wiring behind the unit.

Of course it is also possible that one of the factory amplifiers (if this system has them--I don't remember exactly) has gone bad but definitely check for speaker shorts first.