Hi Chris -
You can do an easy check on the temperature gauge on the block by:
1. Looking at, and understanding the graph I posted.
2. Taking your ohm meter and measuring the resistance from the center conductor of the original temp guage and the engine or a good solid ground. With the engine cold, it will be higher than 160 ohms.
- That's the first test.
3. Then start your engine, and either drive your car, or let it idle until you think the engine is warmed up. Then measure the resistance of the temp sender. If you have a thermal IR gun, you can find the temperature of the swirl tank, or the engine block right next to the gauge, and it SHOULD match the solid purple line.
- That would tell you if the sender is working as it should.
If it is: Then hook the ground line on your gauge to the vehicle's solid ground. Then hook up the "(+)" wire on the guage to your temp sensor.