bfrance

I've found that my new replacement GM temp sensor is sending the reading of the temp wrong to the gauge and need to correct the resistance to make it read correct. Can anyone tell me what the resistance is supposed to be on that sensor? Thanks for your help.

bfrance

The resistance on my sending unit on my 80 Vette is 2350 ohms and the resistance on my friends 81 Vette is 3350 ohms. Eckler's shows that 80-82 are all the same gauge. So here is what I'm going to do. My friend (and electronics expert) is going to put together a 1000 ohm resistor with male and female ends that we can put in line and check the reading. For anyone interested, I'll post the results when I get this project completed. All for now.

427V8

Remember that;

*The resistance of these sensors is extremely nonlinear.
*Any small change in temp will cause a large change in resistance.
*The resistance at 212'F is the one that matters room temp...who cares!

bfrance

I was wondering about that. My friend thought that we would try this first and work from there. Are you aware of anyone else that has had to recorrect their sending unit? And if so, how much?

427V8

Other people have used resistors to make another sensor work with the Vette gauge, they had to reduce the resistance I believe, check the achives...

Barry's70LT1

On my 'other' car, I used a resistor to calibrate the sensor that shows outside temperature. It was off a few degrees, I was just being **** about it.

I used a variable resistor mounted inside a small plastic tube. I mounted a female connector on one end and a male on the other and sealed both ends. (epoxy)
Drilled a small hole in the side of the plastic tube to access the slot in the valiable resistor. Used a small rubber plug after calibrating to seal the hole.
The sensor was in the grille and needed to be water proof.

You could use a variable resistor to obtain the proper calibration, then measure it and install a fixed resistor.

Put the sensor in a pan of boiling water, with the wire connected to the temp guage, jumper cable from the sensor body to engine block, and adjust the variable resistor until you reach 212F.

greg454

I bought a new sensor from napa and it was way off. So I bought a new sensor from GM and it also was way off. Anyway after experimenting with the sensors in a pan of hot water and using a variable resistor to see what my temp gage reads at what resistance, I found that a 10 ohm resistor in series with the sensor gives me an accurate reading [within 5 degrees of the mechanical gage I mounted in the passenger side head] accross the whole scale. I think I got lucky that it was that linear. The new sensor has the number 45 stamped into the bottom of it, if yours does too you may want to try a 10 ohm resistor.

bfrance

Thanks for all the input guys. My friend has a variable resistor pod that we are going to hook in line with the sensor. Then, on a hot day, I'll get the engine as warm as it will get and with a meat thermometer I'll measure the warm temperature in the radiator and bring up the resistor pod so that the temp gauge reads the same as the themometer. I think that this will be about as close as I will be able to get. Then replace the pod with a permanent fixed resistor. Then at least I'll know that it reads correct at normal running temp. If it gets higher than that I'll just know that it is getting hot. Hopefully, I'll never have to find out just how hot. I'll keep you posted on the outcome. Thanks again.