Glow plug dash light and Glow plugs not working

[n4khq]

This morning was the first time the coolant temperature was below 32 this year. I tried for about 10 minutes but the tractor would not start. The glow plug indicator on the dash would come on with a relay click and turn off with a click. I have tried to get it to heat by turning the switch on off with no success about 1 second time. The tractor has a relay that controls the glow plugs under the dash. I am think the relay should get an ohm reading from the coolant temperature sensor and sets a timer as to how long the glow plugs should be on. I am planning on replacing the relay. Do you guys agree? If so any suggestions as to how remove instruntment pannel cover or dash.

 

[Dave_eng]

This morning was the first time the coolant temperature was below 32 this year. I tried for about 10 minutes but the tractor would not start. The glow plug indicator on the dash would come on with a relay click and turn off with a click. I have tried to get it to heat by turning the switch on off with no success about 1 second time. The tractor has a relay that controls the glow plugs under the dash. I am think the relay should get an ohm reading from the coolant temperature sensor and sets a timer as to how long the glow plugs should be on. I am planning on replacing the relay. Do you guys agree? If so any suggestions as to how remove instruntment pannel cover or dash.

Re-read post #13 and give this method a try. If it does not fire immediately, something more serious than a GP controller is wrong.

Dave

 

[russell.still.5]

Re-read post #13 and give this method a try. If it does not fire immediately, something more serious than a GP controller is wrong.



Dave

Does the indicator light come one when you use this method?


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[hope to float]

Does the indicator light come one when you use this method?


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According to earlier posts it does not. Give it 10 or 15 seconds

 

[n4khq]

The indicator light does not come on. I tried holding the key in the start position for 15 seconds and it still does not start.

I have more information, The design for my tractor sucks, at 32 degrees, it suppose to stay on for one second, which it does; takes -4 degrees for max heating of 15 seconds. Solutions include straight wiring the glow plugs with a button. Possibility changing the glow relay. The original blades the relay under the dash was over heating. The replacement glow relay has copper and larger blades.

It was 23 this morning and the glow plugs stayed on for 5 seconds which is what it is designed to do.

Another solution is getting the temperature sensor to send a cooler temperatures. I don't know how you would get the replacement sensor mine is working according to specs. The coolant sensor is sending 117 ohms at 248 degrees and 808 ohms 122 degrees. It appears to me that inserting a resistor of the correct value in series would increase the resistance and cause the glow plugs to stay on longer. Anyone have any suggestions? Thanks

 

[Blondie70]

Put a manual switch/button on it and be done with it.

 

[n4khq]

Would 16 gauge wire to manually close the glow plug relay work? I am think one hot wire (12 v) is all I would need.

 

[200mph]

Would 16 gauge wire to manually close the glow plug relay work? I am think one hot wire (12 v) is all I would need.

Yes it should be enough to handle energizing the relay (non-power side of relay).

Let us know how the work around works for you.

 

[lugbolt]

Engine off. Key out. Park brake set. Open hood.
From left side of engine (left as you're sitting in the operator's seat), follow upper radiator hose. It goes to the engine. Near there is the coolant temp sensor. Green connector I think. Unplug it. Get back on tractor. Reinsert key, turn to "on". Does glow lamp come on and stay on a while? If yes, sensor could be bad....or the coolant isn't cold enough to make the glow plugs work. If glow lamp does not illuminate, check for power at the glow plugs themselves. Power? Lamp burned out. No power? Suspect relay, but then you're on your own for testing it....it's more or less ECU controlled and I do not remember if it's 5v to trigger the relay or 12v--and on that note, if you are going to rig the relay, you'll want to know if the relay's coil is triggered by 5V or 12V, either way, disconnect it's trigger somehow so that the controller isn't hurt.

 

[lugbolt]

Also worth mentioning is fuel.

As it's gotten cold, a lot of tractors still have summer diesel. Summer fuel doesn't start very good when it's cold outside. Old diesel doesn't start/run quite as well as fresh diesel.

The glow system, at least on the bigger M-40's, also controls a "toaster" (as I call it...it's actually an air heater in the intake manifold), so it's not JUST glow plugs that are controlled. WSM outlines how the system works.

 

[Dave_eng]

The indicator light does not come on. I tried holding the key in the start position for 15 seconds and it still does not start.

I have more information, The design for my tractor sucks, at 32 degrees, it suppose to stay on for one second, which it does; takes -4 degrees for max heating of 15 seconds. Solutions include straight wiring the glow plugs with a button. Possibility changing the glow relay. The original blades the relay under the dash was over heating. The replacement glow relay has copper and larger blades.

It was 23 this morning and the glow plugs stayed on for 5 seconds which is what it is designed to do.

Another solution is getting the temperature sensor to send a cooler temperatures. I don't know how you would get the replacement sensor mine is working according to specs. The coolant sensor is sending 117 ohms at 248 degrees and 808 ohms 122 degrees. It appears to me that inserting a resistor of the correct value in series would increase the resistance and cause the glow plugs to stay on longer. Anyone have any suggestions? Thanks

Others have answered the question re any GP light coming on when using the manual method.

I would be investing in a new GP relay. It sounds like nothing is sending power to your GP's even when the dash light comes on briefly. Fooling the controller to mimic a lower temperature wont help if the relay is bad.

Dave

 

[Dave_eng]

Would 16 gauge wire to manually close the glow plug relay work? I am think one hot wire (12 v) is all I would need.

You are treading in deep water here. The GP relay is powered on all the time and is controlled on the ground side of the relay coil.

If you cannot locate the problem far better to spend some $ and have a Kubota pro fix it.

Dave

 

[n4khq]

Lugbolt, The temperature sensor for my M6040 is on the right side from tractor seat at the back of the engine. I have not tested the sensor with a ohm meter but I am sure it is working. When it's 30 the light stays on for about 1 second. At 23 degrees it stays on for 5 seconds. This is what the specification says it should be doing. Thanks for the reply

 

[n4khq]

Kubota had a problem with glow plugs relay not carry enough current. The current replace part has copper blades that are wider on the power side of the relay. Looks like there is a 50 amp fuse suppling the current for the glow plug. I have a relay on order. While I have the dash panel off I plan to add a manual override button to activate the glow plugs. See attachment and let me know if I am missing something. Thanks for all the replies.

 

[n4khq]

The attachment on my computer was too small to read, here is an enlargement

 

[n4khq]

The schematic I attached is not correct. I would be applying power to the glow plugs and not closing the relay. I guess posting is good for catching your mistakes.

 

[n4khq]

I am having trouble understanding the glow plug relay schematic. My guess is I should add +12 volts to the "a" blade of the relay in order to close the relay. In addition the power must require the switch to be on. Sorry for the incorrect post. Thanks

 

[russell.still.5]

I don’t understand the schematic either. I thought there would be a hot and a ground going to the relay to control the relay and then a then a 50A hot which is controlled by the relay which goes to the glow plugs. If that make any since whatsoever.



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[n4khq]

It an over simplification here is a better schematic from the same service manual. The problem is not having the sensor circuit and timer controller in the dash information. In addition the shop manual over simplifies the schematics. If I put the manual override in, I will look at a double throw switch that will break the 12 volt being sent from the sensor / timer. I know the sensor sends an ohm measurement that represents temperature to the timer in the dash that supplies voltage to close the glow relay the required amount of time depending on the temperature. I don’t have a clue what the back voltage will do to the timer circuit in the dash.

Thanks for looking and the reply

 

[n4khq]

The glow plug relay load is heavy wire to a 50 amp fuse. The relay closing wire is on a 5 amp fuse in the schematic of my previous post