Engine Temp Sending Unit?

[Macgyver]

Can anyone tell me where the temp sending unit originates from under the hood adn possibly what color it might be? Ive been looking everywhere adn i cant seem to find it. None of the wires around there from all the emissions stuff seem to match the connector on the sensor and the Haynes aint helping much either.

thanks

 

[80redbeast]

The wire is dark green. The sensor is located between cylinder # 1 & #3.

 

[Stallion]

When you say "between", what do you mean?

 

[brusso]

Take a look at the back side of the alt. You'll find the wire coming out of the "harness" ,that has the alt wires in it, leading to the block between number 1 and number 3 cylinders. Or there abouts.

 

[80redbeast]

When you say "between", what do you mean?

Cylinder 1 is at the front of the block. Cylinder 2 is next to it. The space in between 1 & 2 has a hole in it that the sensor screws into. Right between the two spark plugs, maybe a little lower. If not, you will see a plug screwed in.

 

[Macgyver]

Thanks for the replys guys. Let me see if Im right, the wires dark green and should be coming from the alternator? Does it have a clip like the tach and battery wire that click in to the distrib cap?

I was just thinknin that it would originate from the firewall .

 

[80redbeast]

I think what Brusso is saying is that the wire is coming out of the harness that goes to the alt, not that the dk green wire is coming out of the alt. It does originate from the firewal, but in a harness with all of the other wires.

 

[brusso]

I think what Brusso is saying is that the wire is coming out of the harness that goes to the alt, not that the dk green wire is coming out of the alt. It does originate from the firewal, but in a harness with all of the other wires.

Yup, thats what I meant.

 

[brusso]

Thanks for the replys guys. Let me see if Im right, the wires dark green and should be coming from the alternator? Does it have a clip like the tach and battery wire that click in to the distrib cap?

I was just thinknin that it would originate from the firewall .

The connection is similar but not as secure as the batt or tach connection. It is very easily knocked loose. The sensor just has a male spade (flat tip screwdriver) looking thing sticking out and the wire connector slides over it. There isn't anything for the connector to snap onto as securely as that batt, on the distributor cap.

 

[Macgyver]

THanks a lot Brusso youve got again. The only thing is that theres 4 wires that look just each other and have the same type of clips. They are yellow red and 2 greens. And I have one yet to try but Im thinkin gthat its not going to work.

If I touch the wire to a power source will it make the temp gauge go to 300degrees? Or can I get a voltometer to test to see if theres power in the wire? Shoule there be?

It was working when i detached it though.

 

[brusso]

THanks a lot Brusso youve got again. The only thing is that theres 4 wires that look just each other and have the same type of clips. They are yellow red and 2 greens. And I have one yet to try but Im thinkin gthat its not going to work.

If I touch the wire to a power source will it make the temp gauge go to 300degrees? Or can I get a voltometer to test to see if theres power in the wire? Shoule there be?

It was working when i detached it though.

Can't help you there. My 75 only has one wire to the sensor. Now that I think about it, I think that the connection might be more like a spark plug with the end unscewed. In other words, a small stud with a elbow shaped conector on the end of wire. Also, the sensor acts as a variable resistor. So there should be voltage on the wire going to it.(when key is in on position) So to test gauge/wire you would apply a ground to wire and see if gauge fully deflects.

 

[Macgyver]

So if i ground the wire, or touch it to the frame the gauge should go full hot right? UNfortunately all the wires w/in the area have voltage runnning threw them. I now the gauge is still operable because when I was driving on the highway I hit a bump and the gauge statrted to fluctuate rapidly between 300-250 for a few minutes.