Oil Pressure Gauge...
 

Since I bought my car a year ago the oil pressure gauge has not worked. It always reads 0 psi, and now I'm finally ready to tackle this problem. I cleaned off the contacts from the sending unit and its blade connector, and got nothing. So I then simply attached the blade connector to ground and similarly got nothing.

I know now I either have bad wiring (the previous owner was a hack, so I wouldn't be surprised) or a faulty gauge. Are there any typical problem areas I should look at? if I do have a faulty gauge, can I replace it without replacing the whole gauge cluster? I really don't want to rip apart my dash too much for this... :(

what beand is the oil guage

best thing to do is just buy a whole new oil gauge instead of trying to fix the factory one. that is what I did and looks better.

I'm pretty sure it isn't the sender, but just in case if anyone could tell me how to test it that would be awesome. I know the factory gauges kinda suck, but it looks a hell of a lot cleaner than having a bunch of extra gauges hanging out around my dash or pillar.

If you grounded the sender wire to the chassis, you created a short circuit. Now, in your case it sounds like either the gauge or sender failed in the first place, but it's still not a good idea. Doing so with a functional gauge will fry it. The resistance from the sender normally reduces the amount of current the gauge sees.

The FSM (factory service manual), which can be downloaded through the FAQ, has a test for the gauge that uses resistors of various sizes. Unfortunately this would be useless to test your gauge, since it was either fried already, or you fried it. You're looking at replacing the gauge at the very least, and possibly replacing the sender too. Both parts can be purchased through a Mazda dealer.

The simple and easy test to see if the gauge itself works is to simply ground the wire that hooks to the sender and sends its signal to the gauge. The gauge works by using resistance. The higher the resistance, the lower the gauge reads and vice-versa. So, by grounding out the signal wire to the gauge, the gauge should simply max out. The water temp gauge works the exact same.