We have a Nordyne G6RC Series 90+ Upflow Condensing Gas Furnace. I think its about 8 years old, but I'm not exactly sure.
It seems to be having a problem with the induced draft blower. What's happening is when the thermostat calls for heat, the induced draft blower won't come on, and then I guess the pressure switch doesn't close, so the LED starts blinking the "pressure switch open" code. If I tap the induced draft blower with a screwdriver or jiggle the wires around, it usually kicks on, the code stops blinking, the ignitor gets hot, and the burner lights. Then the circulating air blower comes on the house warms up. But once the furnace shuts off, it usually won't kick back on again until I tap the induced draft blower or jiggle the wires again.
I'm wondering if I need to replace the whole draft blower, or might this be just a faulty wire or connection? Can I test the wires/connections/circuits with a multi-meter? If so, how? Or am I on the wrong track altogether? I'd be grateful for any advice anyone can give me.

Your diagnostics sound very plausible. Follow those wires back to where they connect to the board and check for 120 V. Or does the motor get very hot? If you have 120 and/or the motor gets real hot it is a bad inducer 9 out of 10. If I had to guess the thermal protector in the motor is going bad and I have no idea how you would fix it besides replacement. Just be sure the loose connection is not at the PC board.

Well, I checked the volts at the board and got 120. The motor does get warm when the furnace is running, but not too hot to touch with bare hands. To be honest, though, the furnace has been working fine since the last time I jiggled around the wires, which was just before I posted my question. So now, I guess I'll just wait and see what happens...
Thanks for the advice.