How many wires go to it? Why are you checking it? Do you know if the gauge itself works? Is the sensor still on the car or do you have out in your hand? You'll most likely want to check ohms across the sensor. It really helps to have a repair manual if you're gonna be working on your own car. It would have specific instructions and probably even pictures.
the best way to check wiring is to first take the red end of the meter and turn the dial to 20v in the dc section, then take the red lead and probe into one of the pins and take the black lead and put it on a bolt on the frame or if you can reach the battery go straight to the ground there, if you get a reading of 12.6 or so volts you kow thats your power wire, and if nothing and im assuming its a 2 wire sensor then that would be your ground, but just because you have 12 volts doesnt mean the wire can carry any amperage. it may be corroded or broken, so take a 12 volt bulb from your head light or whatever and jump the power wire to the positive pin on the bulb and the ground from the sensor clip and put it on the power pin of your bulb, if it shines brightly you know you have good wiring and the only thing left to replace would be the sensor
These answeres are all over the place because testing sensors/gagues will vary tremendously. Here: 1: remove the sensor 2. place in water and heat to 80c 3. set your meter to test ohm impedence and check to see if you're within 57.7-49.3 Pulled from page 15-32 of this manual - http://www.rotaryheads.com/PDF/2nd_gen/Mazda%20Service%20Manuals/1986-88%20Factory%20Service%20Manual/15_body_electrical_system_part1.pdf Originally found on this forum - http://www.rx7club.com/new-member-rx-7-technical-256/89-rx7-temp-oil-pressure-gauge-problem-1004987/
If the coolant temp gauge is bad then the engine light would come on. If the engine light is already on, then check the code. If you did and it says its the temp gauge.... fuck checking it, just replace it lol Sent from my iPad using Grasscity Forum