My power door locks don't work properly. I get nothing on the passenger side when I push the switch up or down.
On the driver's side, I can lock the doors if I push the switch down just right.
So I need to remove the switches.
How are they held in place?
Do they just pop out or is there a catch that needs to be released somehow.
Once I get the switch out, how do I check to see why it is not functioning?

cant tell you how they are held in as you have one of those new fangled c3's...

but for electrical troubleshooting a multimeter and an inductive ammeter will debug just about everything.

make sure you draw a diagram for the wiring hook up before you take the wires loose

Just got done checking the power locks on my 78SA. They would unlock but not lock. Bought a new switch at Pep Boys in the "help!" section. Actually a power window switch. $15. I believe you can swap the actual switch out of the bezel to retain the original bezel. Held in place in the door panel with spring clips. Looks like you can pop them out with a 1 inch scraper but decided to take the door panel of instead, didn't want to risk scratching it. The opening in the door panel is reinforced for the switch.
Anyway, hooked it up and no change. Drivers side. Went around to the pass. side and jiggled that switch and they started working. Jiggled it some more and stopped. Jiggled again, working! Figure the contacts must have some corrosion as I did notice the drivers side was a little cruddy and scraped the 5 contacts. Right now they work! Will probably be pulling the pass. side panel to more closely check that switch.
But on mine, BOTH sides would unlock/not lock the same before I started. Each switch controls both sides. Not sure why your pass. side doesn't react.
Mike

Anyone having trouble with switches, I have saved myself a lot of heartache on boats, generators, and cars by keeping a can of Q D Electronic Cleaner Spray handy.
Q D means: Quick Drying. Just spray it directly into the switch from the outside, and unless you have a bad switch, works every time. It is useful for contacts, plugs, etc.
Here in this salt air, and especially on boats, you need it.

Is that something I can buy at RadioShack?

Go to NAPA, they have more product dedicated to cars and trucks. The can is a 11 oz. spray, and is red with white and black labeling. It has a NAPA label on it, and is made by CRC for them. The address on the can:
CRC Industries, Inc. Warminster, PA 18974
Phone: 800-521-3168 (Technical Info)
800-272-8963 (Customer Service)

It is named: QD Electronic Cleaner