Temp sending unit advice (and oil sending unit)

[87MJJeep]

When I upgraded to gauges about a year ago, I got my new temp and oil sending units at Autozone. The temp sending unit lasted less than a year, and well under 3K miles. When it read low over the winter, I just figured it ran cold and maybe the thermostat was staying open. We had a relatively cool spring, so I still assumed I had a stuck open stat. When the real heat hit in June, I knew I had a gauge issue. After reading several posts on here, I knew to check the ohm reading, and I could tell the gauge was reading what the sending unit was telling it. I got my Mopar sending unit today. Problem solved.

[ratrapp]

things like sending units and sensors need to be oem.i put 3 coolant gauge switchs in my stepdaughters 96 ford contour.all three read different and wrong.an oem ford switch fixed it.

[87MJJeep]

things like sending units and sensors need to be oem.i put 3 coolant gauge switchs in my stepdaughters 96 ford contour.all three read different and wrong.an oem ford switch fixed it.

 

Ya aren't kidding. :( Here I am a year later, and I figured out my oil leak. It's the AZ oil sending unit. OEM, here I come.

[Boots]

Would you mind describing how to test the temp sending unit? I think mine is bad but want to make sure it's not the gauge.

 

Thanks

Chad

[87MJJeep]

Would you mind describing how to test the temp sending unit? I think mine is bad but want to make sure it's not the gauge.

 

Thanks

Chad

 

Check this out. A post by Eagle in thread:

 

viewtopic.php?f=2&t=31282

 

Quick test of gauge and wiring:

 

Turn on ignition. You can start the engine, just stay clear of the fan and exhaust manifold. The engine does not have to be running, but the gauges must be energized (i.e. don't turn key to "Accessory").

 

Observe where needle sits. According to you, it should be on cold.

 

Remove the wire from the top of the sender. Do NOT touch it to anything -- isolate it, or you hold it while an assistant reads the gauge. Where is the needle?

 

Now take a probe (or a nail, or screw, or length of stiff wire) and ground the wire directly to the engine (block or head, so big hunk of clean metal).

 

The sender resistance range is 0 - 88 ohms. With the wire removed from the sender, there is no circuit. This is equivalent to infinite resistance. The needle should peg on the hot side. When you ground the wire, the resistance should be close to zero. The needle should be all the way down to the cold side of the scale.

 

If not ... the gauge or the wire to the gauge has a problem.

 

_________________

Eagle

[87MJJeep]

Check this thread too:

 

viewtopic.php?f=2&t=30657

 

And this one:

 

viewtopic.php?f=2&t=15074&hilit=ohms+temp

 

Note Hornbred's post at Thu Feb 26, 2009 7:16 pm:

 

That's correct. The sensor is actually called a thermister and varies resistance according to the temp it sees. The gauge cal figures are:

 

1365 ohms = 100°

93.5 ohms = 220°

55.1 ohms = 269°

[Boots]

Thanks!!!

Chad