JD 455 temp gauge not moving

[theedudenator]

My gauge does not move. All other gauges and lights are ok.

I looked on JDparts and it is showing a Temp Sensor and Temp Switch close to the thermostat.

I am assuming the temp gauge is working off resistance?
So If I pull the wire from the Temp Sensor and ground it, the needle should move?

 

[TedLaRue]

That is correct. If you ground the wire that goes from the temperature sensor to the temperature gauge, the gauge should read "hot". Not sure about your machine, but on mine that wire is yellow/blue.

If grounding that wire gives you a "hot" reading, then the sensor is bad.

If grounding that wire does not give you a "hot" reading, then test the gauge. (1) One pin on the gauge should have 12V battery voltage (key on engine off). (2) Another pin should be connected to ground (near zero resistance to ground) always. If either of these fails, check the wiring.

(3) The other pin goes to the sending unit. If you ground that pin while the other two wires are connected (whether or not this pin is connected), then you should see a reading of "hot". If so, check the wiring from that pin back to the sending unit. If not, the gauge is bad.

If you have an ohm-meter, you can measure the resistance from the sensor output to ground. The resistance should go down as the temperature goes up ("negative temperature coefficient").

I'm not sure about the "Temp Switch" you mentioned, unless some models used an on/off idiot light instead of a gauge. Since you have a gauge, you can probably ignore that part.

 

[caseyvand]

With reference to the "temp switch".....I think it is designed to protect the engine from overheating by automatically disengaging the PTO if it is engaged. The proper procedure to follow should this happen is to push down on PTO switch and let engine idle to cool and bring temp gauge needle out of the red. (clean air intake and radiator screens or reduce size of winter baffle)

 

[twoone]

been there but on a ford this is what I learned and it is almost a repeat of Teds link Starting with a cold eng. Remove wire from temp. sensor short to ground ga. should move to hot do not leave this wire on gnd remove as soon as ga. starts to travel that will test the wiring as well as the ga. next test the sensor with an ohm meter one lead to the spade and the other to a ground should read some were above 500 ohms next remove raid.cap start eng. watch for a flow to start feel upper hose and if you have a temp gun or a thermometer check eng. temp for warming also take your ohm meter and start checking the temp. sensor to gnd it should start reducing the resistance the warmer eng. the the less resistance I would assume the t-stat will start to open some ware around 71degrees c and 85degrees c fully open(ck you tractors spec.) you should see movement in the raid.and the hose should get hot when the T-stat opens as well . ok>, sensor resistance drops ==sensor is good,. we know ga. and wire are ok. if the hose and water stay only warm and do not get hot enough to reduce the Resistance at the sender ==sounds like a bad T-stat . Good luck and I hope I was of Help, Paul

 

[theedudenator]

I pulled the wire from the sending unit and grounded it on the engine.
The gauge did not move...

Too much work to pull the dash apart now, maybe later.

 

[twoone]

Hi"
? Did you have the power on when you grounded the wire to the sensor ?(wire to a good clean unpainted surface) if so and the ga moved toward hot remove the ground or the power do not leave it on if there was movement . You might want to leave it on to check the wiring to the ga. but at least now you know which way to go to complete you troubleshooting Paul

 

[theedudenator]

I had the power on.

The gauge is stuck in the middle.
No movement when I grounded it.

 

[twoone]

Ah' you never said it was stuck in the middle sounds like a gauge to me as you bypassed every thing else but you need to see a diagram . could be two problems cause your still overheating and the ga is not telling you. I believe the ga should have returned to cold as it cooled when you shut down right? so even if the sensor were bad it would not cause the over heat problem. J wonder did you ever read the sensor resistance? and check the wire to the sensor for voltage? Paul

 

[theedudenator]

I do NOT think I am over heating.

I just want the gauge to work!

Ha!

I need to trouble shoot the gauge

 

[twoone]

You never have told me if you have power on the wire to sensor and am not familiar with your system enough to tell you any more with out some of the meter reading I ask for and the switch in the system is unknown to me perhaps the power to the ga. goes though it, but with out meter reading am lost. I was going to tell you to follow Ted advice on post # 2 but your going to need a ga. there as well. However right now am still looking at the ga. Paul