Does anyone know how to test the temperature gauge sending unit /sensor. The sensor with one wire going to it ? Not the coolant sensor next to the time switch. 22re motor

 

Should change resistance when heated.
Not sure of what values should be.
No doubt procedure is in FSM.

 

I couldn't find anything about this sender in the FSM or Haynes manual. No values seem to be listed for this sending unit.

 

Not sure what year you have could make a difference around 146 ohms at at a140F

Dropping to around 24 Ohms at 239 F

This is out of a 86 22REC yours may be different.

 

91 22re motor.

My senders ohms increase as the sender cools down.

As the sender warms up the ohms drop

Here is what I tested my sender at, not sure if it is working correctly


.500k ohms at 70'f

400 ohms at 130'f

 

0.500k ohms is the same as 500 ohms. Which is not much of a difference from 400 ohms.

The temperature curve for the ECT sensor is shown here: http://personal.utulsa.edu/~nathan-b...98engineco.pdf This is the characteristic curve for an NTC (negative temperature coefficient) resistor. I'd like to say that all NTC resistors have the same values, but they don't. Would Toyota use the same parts in all of the temp sensors? Maybe, except the ECT sensor is a two wire device and the gauge sensor is a one-wire, so I'm not going to make that leap.

Note that the ECT sensor should be about 500 ohms at 130°F, and 2000 ohms at 70°F.

 

I wonder why my meter reads it at .500k ohms....I put a 500 ohm resistor across my test leads and the meter reads 500 ohms, but when I put the temperature sender across it, it reads .500k ohms and 500 ohms like it should.

 

Do you have an auto-ranging meter (many today are). http://www.autoshop101.com/forms/h4.pdf

.5k and 500 are both correct readings; you just have the meter set on a different range.

 

I guess some of those digital multi-meters are the bees' knees, but I'll take my analog Simpson 260 any day.
The digitals are sometimes too smart for their own good.

 

I tell the kid to go get the Homer!!

 

I tested the old sender..and it was within spec, but then suddenly decreased after reaching a certain ohm.

I went ahead and found a new sender at autozone..and it works fine now...Thanks for the help.

 

my 87 22re has 2 orange look like reset buttons on the top. they about the thickness of your thumb nail, pushed them back in but i already changed it out so don,t know what they did.