I have an '01 also. Remove the kick panel on that side and look for a loose/bad connection, or disconnected wires, etc. There are a bunch of connectors under that panel. Taking off the door panel at the same time may help to track the wires. Use the wiring schematics in your shop manual to help you identify the proper wires by color.
I had bad wiring to both front speakers, I ended up running new wires. Problem solved.
I had intermittent operation of the front windows, I removed and opened up the armrest switch box and cleaned all the contacts. Problem solved.
In my opinion, the later years had piss-poor wiring, very low quality. Just keep up w/ them before they add up.
