When your Mazda Miata window switch isn't working, pinpointing the source of the problem is not that hard. You only need the right tools to figure things out. Perhaps the most common problem encountered with a window switch is dirty contacts. Because of the accumulation of dust and other particles, the current couldn't get through to the contacts, causing a slow opening or closing of the windows or no movement at all. Sometimes, though, wear and tear just takes its toll on the switch and renders it no longer functional. But to make sure you do not to throw away a switch that's still good on the inside, here are simple tests to confirm that they are no longer functional.
By using a voltmeter, you will be able to determine the voltage coming from terminal 4 to the ground and from terminal 5 to the ground is correct. To do this test, simply remove the faulty Mazda Miata window switch from the door and turn it to the "open" position. Then, attach the voltmeter to the switch plug. Check if it is at 12 volts. If it is not, the power and the wires to the switch are not quite sufficient to power up the opening or closing of the window.
Another test that goes hand in hand with the use of the voltmeter is using an ohmmeter to determine the resistance of the various terminal combinations. Put the switch in the "open" position and attach the ohmmeter to different terminal combinations. Take note if there is a low resistance from terminals 1 to 4 and from 2 to 3. Next, set the switch to its "off" position and then attach the ohmmeter to the varying terminals. Observe if there is a low resistance from terminals 1 to 3 and from 2 to 5. Otherwise, your switch may be dirty or may have rust.
A test light is a simple electronic test equipment that is used to determine the presence or absence of electric voltage. Use this to trace the electricity that flows from the switch to the motor. If the flow of electricity that is reaching the motor is continuous, there is no problem with the switch. You may want to check your window regulator; if the assembly is stuck, it may be the cause of a non-moving window.