Guru's,
Does anyone know what the resistance should be for the temp sending unit at different temperatures? My temp gauge reads low, and doesn't move much from cold to 180. I heated the sending unit to 180 and set the needle in the middle, but when I cool the sending unit to room temperature it only goes down to about 3/8 of the gauge, and never shows cold. I thought if someone knows the resistance for the sender at say 80 degrees and 180, I could eliminate that before sending the gauge off.
Thanks for the advice,
Paul Low

If memory servers, mine is about 1000 ohms at 70* or so and near 150 at 212*. I'm guessing, but that is ball-park. But then again, I have an aftermarket guage / sensor which probably isn't exactly like the factory setup.

As dnult suggests, lower temp, higher resistance. I've seen them at 5k ohms for 70*F.

Usually, at 180*-200*F, 150-180 ohms. You've stated you adjusted for needle to show 180*F, but now won't show cold. Its out of calibration, I think.

The more correct way is to find the amount of current needed for full scale deflection. Induce this current value and adjust for full scale. Now, did the manfacturer give the value? Probably not.

One thing that I just found, and this may or may not have any bearing on what you are doing....I have two temp sending units, one for a fan and the other for the gauges. I decided since my fan wasnst coming on at 195* which is the temp it should, I switched the locations in the center manifold. When I pulled the one sensor, whoever put it in there used RTV and it was clogged at the bottom of the sensor. I am sure this is my problem about not getting accurate readings. I will test mine again today, but from what I understand, they are not suppose to have rtv or anything that will insulate them from the manifold...

Very true, the sensor body needs a good ground to the host item.

Does anyone know the procedure for ohming out the temperature gauge, or do you have an extra one you could check the resistance across all the terminals on?
Regards,
Paul Low

According to the Wells replacement parts catalog, the resistance for 100 degrees is about 390 ohms and at 260 degrees, about 102 ohms.

Larry

For more on the subject, try here
http://www.chevelles.com/forums/showthread.php?t=53657