How do I test coolant temperature sender?

Sensor keeps coming up when I do a general search. I realize these (sensor/sender) are often used interchangeably, yet are two different things. & I can't find it in the FSM.

 

Well, what are you checking?

The sender, is independent of anything and simply tells the gauge to go up or down.

The sensor, communicates with the computer to tell it how hot the engine is running.

Sender is a single wire ordeal, and it's what...resistance/ground? I forget.

Sensor is two or three wire.

 

Testing the Coolant Temp Sensor in the FSM can be found in the Fuel Injection section, one would think it would be in Cooling.
In a nutshell its "stick it in water and read resistance as you heat the water.
Not sure of the year or engine of this chart (FSM) or if it matters.


Make sure you are testing the correct one.
Red is for the dash gauge, Blue is for the ECU.

 

Back in June when I did the intake manifold gaskets, injectors, etc, some wise people (you all) suggested I change out the sender & sensor whilst I had easier access. Don't recall why, however I didn't. Recently I had the plenum off, so figured I'd swap out the sender. My idle went way up, 1100 (park & neutral). Also, it comes in at 1200 after highway driving. Anyway, thought I'd check it. Hard to tell for sure cuz while it has resistance, I can't find any info on what it should be. Other than that, 10-ish voltage & it passed the gauge test.

 

Right. I did find that. That's for the sensor though. I was looking for the sender.

 

Run a gauge off your OBDII; that utilizes your sensor.

Compare the temperature climb (on your digital gauge that you connected) with your dummy gauge on your dash.

If you really want to monitor temps, you need to go with a separate gauge anyway. That's why Ultragauge and Scangauge are popular options.

I would never rely on the factory dummy gauge for something as important as coolant temps.

 

Wait, wait. Before I read any replies, I'm just going to add to my last post that I totally agree the sender should have no affect on the idle, however it is the only thing I replaced other than new gaskets.
Ok. Now I'll check out the replies after my last post.....