Bought the Grand Caravan used with non working head unit. The harness plugs had been removed so an adapter for the new stereo isn't likely. Hooked the new stereo up with tons of problems. Only FR speaker works w/ poor quality. No rear speakers at all. Frustrated after 4 hrs. of trying to figure it out, when I pulled it out of the dash the last time a wire shorted and now key fob won't lock doors and interior lights only come on if ignition is on. I wired it according to the diagrams but something else went wrong somewhere. I have the Infinity system which I hear is problematic when installing aftermarket radios. Any thoughts how to fix this?

 

The Infinity system has amplified speakers. The factory radio supplies power to a dark green with red tracer wire to actuate a relay that supplies power to the speakers.

You also probably blew a fuse, check under the dash, driver side and under the hood by the battery.