TC 55 Temp gauge inop

[jskyking]

The temp gage on my TC 55 has become inoperative. I sure would appreciate any troubleshooting ideas.
thanks
jay

jta320@comcast.net

 

[jinman]

I'd bet your gage is very much like the one on the TC45D/DA tractors. Here is a link to describe troubleshooting and repair.

 

[IH3444]

J Sky King....any luck?, mine seems to be on the fritz also. Not repairable like Jinman's. Whole unit is $409. Glad I bought blue now!

 

[IH3444]

Did the Jinman test. Grounded the sending unit wire, gauge pegs to max hot range. So gauge is good. Now to check for stuck open thermo, or faulty sending unit. Does anyone know of a test for the sender? I have a factory manual. Cost $300. No test for either the gauge or sender. Another waste of money. Is there an ohm test for the sender? Next step is to pull thermo and look at it. Glad I bought new! LOL

 

[jinman]

IH3444, I can only assume that your temperature sending unit is very similar to mine on my TC45D. My $300 manual has specs.

95 degrees F - 670 ohms + or - 80 ohms
176 degrees F - 118 ohms + or - 6 ohms
221 degrees F - 54.5 ohms + or - 2.7 ohms
239 degrees F - 42 ohms + or - 2 ohms

If you remove it, you can use some boiling water to check it or leave it in and compare it to the reading of a hand-held IR thermometer.

BTW: I found this info in the electrical section of my manual, but it is not located near the info on the temperature gage. It's about 50 pages before that.

Good luck. It's good to know your gage is working properly. If you have a potentiometer or low ohm resistor handy, you could also check that the gage will read the proper value for a given resistance of the probe. That would be a good thing to know.

 

[IH3444]

Thanks much Jinman. I did use a hand held IR Thermometer on it, and at the thermostat housing the temperture was 138F, after a typical running of 30 minutes. This implied to me that the thermostat is sticking open. I just wanted to eliminate the possibility of a faulty sender before pulling the housing off to extract the thermostat. I'll check the ohms, thanks for posting the numbers I should be reading off the meter.

Thanks Again!

 

[IH3444]

Jinman, did the resistor checking with multiple resistors. Gauge didn't even budge. Voltage on the sender wire from the dash gauge is 4.2volt. No referenve in my manual of proper voltage from the gauge. When wire is grounded, the gauge still pegs. Any ideas? I'm going to get a spare thermostat gasket and check if the thermostat is stuck open, or the dingle-berry is wedgeing it open.

 

[jinman]

Well, if the gage pegs when the wire is grounded, there must be some point where it will read an intermediate value. That's a baffling response. From the list of thermister readings, my extrapolation is that a 100 ohm resistor should give you a 200 degree reading which should be right at the top of the green range or slightly into the red.

How did your wire in the resistor? I would put one end to a good ground and jumper the other end to the wire coming from the gage. I used to have several resistor substitution boxes where you could dial in any resistance you want, but I think I sold those many years ago. I don't even have a resistor so I could verify my theory on my tractor. A potentiometer would be the best tool because you could dial in the value that gave you the proper reading and then read its value with a VOM.

 

[IH3444]

I'll be sure to find a good ground. I think that's my problem....Thanks Jinman!