Temp sensor/ gauge not reading....

[ellisjay2]

Dropped another 350 in and my temp gauge isn't reading after I let engine run to normal temp feeling top radiator hose...I'm not sure if wiring is bad from being old or sensor itself has gone bad, I've forgotten how to test sensor with fluke meter, and all else fails what's the route to go and difficulty to run new wiring and sensors for gauges. I still have factory dash clusters and all other gauges are working.

[mongocanfly]

https://www.youtube.com/watch?v=puNKAW5Nurc

[Pontiac1976]

I guessing the sender is the one in the pic. It looks rust I would clean it with Dremel Tools and small wire wheel on as Accessory. Maybe emery cloth if you do not have the tool. Then re-check the gage to see if working if not make sure the wiring is not broken has a good clean contact. Then do one check at a time till you find out where the problem is. But looking at how rusty it looks I would take it out clean it on a beach wire wheel.

[ellisjay2]

Gauge still not reading......replaced temp sensor, did peg check, gauge will kick all the way to hot when pegged out, I pegged it out running jumper wire from connector to block. That indicates wire and gauge are working right??? Changed sensor, ran truck till thermostat opened felt top hose hot, and gauge still stayed on cold. Not making sense. Only other thing I could think is the adapter bushing inside the block the sensor goes in is corroded. Any other suggestions !!!?????!????

[Dead Parrot]

Grounding the sender wire from the gauge should give a full scale reading. That part sounds like it is working.

Make sure the sender is a gauge sender and not an idiot light sender.
Senders from different year ranges have different temp/resistance curves. Many aftermarket senders don't match the OEM versions. Not unheard of for the parts store to sell an idiot light sender as a gauge sender. They often look similar.

If you have an Ohm meter, check the resistance of the sender cold. Should be high but not infinite. Depending on sender, somewhere between 2500 and 900. Then check hot. Should be much lower. Between 100 and 40, IIRC.

This issue is fairly common. Several threads on the subject.

[Corts60]

X2. You may have installed a temp switch for an idiot light and not an actual sender. Boil it in a pan and if it does not move through a range of resistance as it heats up, then it is probably a switch. You’ll know because you’ll get an o/l reading until the switch closes and then you’ll get resistance all of a sudden.

[ellisjay2]

Anybody have the own part number for the correct temp sender to gauge??

[ellisjay2]

I have a fluke meter, but how do I connect both prongs to sensor since its one prong, then submerge in water???

[ellisjay2]

Problem solved, oreillys gave me the sender for the light the first time, which looked almost identical, when getting the other one, you can tell difference in shape depth, one of the techs caught it. Temp jumps up between C and middle range....but now I have to find oem metal fan, and shroud....not going the electric route....