atkinson40

I wish. The other gauge is a monster compared to the original.

I pulled the senser and hooked up alligator clips and wires to it in a pot of water on the stove. Stuck a thermometer in the water and began to bring the water up in temperature as I monitored the resistance. Here's my readings.

F R
77 589
107 313
122 246
135 192
158 113
178 86
192 69
201 60

Tells me one thing. The head is at 201 degrees when I've measured the sensor resistance to be 60 ohms. Its not overheating. This is the same temperature I'm reading for the coolant in the radiator neck.

These numbers are off compared to what you gave me. Substituting in the 60 ohm fixed resistor and having all the rest of the circuit work fine is pointing to the sensor. Don't want to believe that the new sensor is bad, but maybe. ganna call the dealer and see what a new sensor costs.

At least now I have another indicator besides the gauge I installed telling me the motor is not overheating. -Kevin

atkinson40

Figured out a way to see if the sensor is changing resistance with voltage applied.

Ran the car to hot. Sensor/gauge is reading hot. Pulled sensor wire measured resistance of sensor. 60 ohms as in the past. Put wire back on sensor and measure voltage at sensor. V = 4.7VDC. Stuck an amp meter in series with the wire going to sensor and measured current. Current is 188 mA.

Ohms Law V=IR Sensor resistance is V/R = 25 ohms. Now I know why. Sensor is changing resistance with voltage applied, This should not be. Sensor should only change resistance as a function of temperature.

Pulled the sensor, returned for refund from Autozone, installed the old sensor, and now can't get the old sensor/gauge to fail. Oh well, today was half price day at the junkyard. I picked up 2 sensors for $8.(Dealer wanted $50 for one)

Now I've got a couple of spares to eliminate the sensor as the culprit if the circuit begins acting up again.

I hope this saga is over and I'll move on to the power steering leak from the pump area that seems to have developed when I did the timing belt. I had to move the pump out of the way.

Also need to do the oil pan gasket and figure out the knock when on the floorboard when I take of or go over a bump. Thanks ezone, -Kevin

ezone

Love it. Solid answer, solid reason, proven out in the math.
You said you have a degree in electrical engineering, right?


Makes you want to pull your hair out, doesn't it?

Want to cut the old sensor apart to see what was wrong?

atkinson40

guilty


A little, but I wanted my money back from AZ more.