Temperature gauge Dead

[Teepee]

Hi Every one,
I have read through as many posts as I can and get close to my situation but not close enough.
1997 Ford explorer 2WD
4.0L EFI
Temperature gauge completely dead.. Does not move.

Firstly I tested what I understand to be the temperature sensor.
I checked the resitance between cold engine and hot. There was no difference. I replaced the sensor . I checked to see if there was resistance in the new sensor and it was 34k out of the box. seemed to be about where the chart said it should be. Now I am pretty sure that the new one works fine. I got the part from Autozone (part number : SU284 ) It had two contacts on it as the original did but in both cases only used one of these contacts. The original plug only has one wire going through it into the sensor. At first I thought that maybe my problem was a broken wire but on closer inspection of the plug it has never had a second wire through it. ( It is still molded for one)
I removed the old sensor and replaced it with the new one and swithched on the ignition and still nothing.
I have read some advice in this forum about removing the wire and grounding it to see if the problem is wiring or gauge. When I grounded the wire it peaked the gauge. ( am I safe to assume that the wiring and gauge are O.K.)
I have also read here that there are two sensors in this vehicle. one is a sensor and the other is a sender. As I look at both they look similar and have the same plug ( two contacts ) but one uses the two contacts and the other only uses one.
The only difference between the original and the new is that the new one tapers to more of a point beyond where it the threads into the engine. The original was more a cylinder .
After letting the engine reach normal operating temp. I again checked the resistance and it was now about 2k so it seems that the new sensor is working as specified.
I have also put in a new thermastat.
Can you tell me if the two are the same part number ?
Or is there something else you think I could test before I just settle for a car that doesn't overheat but now has no temperature gauge.

Regards
Tony

did I put any one to sleep.

 

[dogfriend]

zzzzzzz....Huh, what was that?




There are two different coolent temp senders (or sensors). One has two wires, one only has one wire.

The one with two wires actually is the temp sensor used by the PCM (computer) to determine injector timing, etc. based on coolent temp.

The one with one wire is the one which controls the gauge in the dash.

I'm attaching the schematics for both, which includes the color codes of the wires which should connect.

I'm thinking the parts store sold you the wrong sender.

P.S. They aren't the same.

 

[Teepee]

Dogfriend.
Thank you sooooooooooooo much.
After a bit of calling around I found the temperature sender and now I have a working temp gauge.
Once again thank you for your speedy reply and thanks for staying awake through my post.
Regards
Tony