How do you test coolant temperature sensor?
(2011-03-28 14:20:29) 1. Says: If what you mean is the temperature SENDER that goes to the temperature gauge like Neil B is talking about, then do like the first part of what Buster said. The gauge should also read cold when the wire is disconnected, even with the engine warm. That's how you test the gauge and the wiring. If that test checks out OK, but your gauge is still off, then you need a new SENDING unit.If however, you do mean the engine coolant temperature sensor, you DO NOT need to remove it from the engine. You also DO NOT need to boil water. You need to disconnect the 2-wire weather-pak electrical connector, then use an ohmmeter to check the resistance of the sensor. Then you compare the readings you get to a table that applies to the vehicle in question.
This table covers most GM Vehicles;
http://www.napaechlin.com/GM-Coolant+and+Air+Temp+Sensors/Content.aspx
and by that, I don't mean some Mazda or whatever that they slapped a Ford badge on.
If you don't drive a GM or Ford, let me know and I'll give you the email of my buddy that worked at the Ford plant across the river for 30 years, and maybe he'll look it up for you.
But I'm guessing he'd probably just tell you to go..............yourself.2. Says: You need to take out the sensor unit (helpfully this is usually near the top of the engine, near the themorstat) and put it in water you know the temperature of. Boiling a kettle and pouring that into a mug with the sensor is a good way to do it, but don't expect it to show above 90C / 194F as the kettle will go "off the boil" pretty quickly when you carry it out to the car :)3. Says: Most people dont, just ground the lead wire to the engine block and turn the key to the on position, if the gage goes to max then you know its not the gage thats at fault and most likely the sensor, but if you feel the need you'll need a multimeter set to Ohm and a pan of boiling water. or just do it in car and wait for it to warm up and watch for a resistance change4. Says: Take off the leads to the sensor and check the resistance of the sensor when cold, and then after the engine warms up. One should show 0 and the other should show infinity.
Don't know which, because don't know what car.5. Says: They're fairly cheap. If in doubt, just replace it. Tag: How do you test coolant temperature sensor?