Glow plug light staying on

[PaulWinLA]

HI
My MT 225 FD 4 cyl glowplug light is staying on while the engine is running. I replaced the glowplugs yesterday and it started right up, the light went out but came back on a few seconds later. There are two wires going to the glowplug rail, in the same spot. One is receiving 2.3 volts while running (disconnected) and the other is receiving 13 volts (disconnected).
To begin, I can not understand two hot wires connected to the rail, yet I think the voltage should diminish after the motor is running. I think the glowplugs will burn out with constant voltage being applied. This is my first experience with a diesel engine and with no manuals for it I am at a loss. Hope someone can shed some light on this topic. Happy Independance Day everyone.

 

[boggen]

no idea about specific tractor. and no idea about specific glow plug operation.

some times, you turn the "starting key" / ignition switch, and hold to get glow plug going
some times, there is a "relay" that turns on glow plug every time you start tractor, and will stay on for a few seconds then go out.
some times, there is a button you need to press to get the glow plug going
and then the ugly mess, some times mice and other rodents get in and chew up wires causing shorts.

an electrical diagram for tractor would be what you most likely want. and would come a service/shop manual for tractor. you might be able to contact a local dealer, and just get a copy of electrical diagram free or for a few bucks. never hurts to ask.

to state it, normally there are 3 manuals.
--owners/operators manual = were to grease, when to check and change filters, change fluids, what controls do what
--parts manual = most manufactures have online free parts manual. simple diagrams to identify parts
--shop/service manual = much better diagrams of parts, how to tear it apart and how to put it together and check things along the way. along with trouble shooting steps.

if you have a FEL (front end loader) this might be another manual
if you have a backhoe this might be another manual as well.

 

[Oldoak]

I had a similar issue with my L4200GST Kubota a couple of years back. The Glow Plug Controller, located under the instrument panel had failed. About a $50 replacement part. Not sure that is your same problem, but that is what cured mine.

 

[PaulWinLA]

Thanks for the response. You are right, I need some manuals. Am hoping someone on the forum has a 4 cylinder tractor that is willing to look at the motor to see if theirs has the two wire setup on it. I rechecked the voltage and see I made a mistake in my initial post, the one wire has + 12 volts (disconnected) and the other one has -2.5 volts (disconnected). No evidence of mice having knawed on the wiring harness, it looks just like it came off the assembly line. My key simply turns on and the glowplug light comes on, then turns to start and then releases. Like I said, I appreciate your reply.

 

[PaulWinLA]

The tractor straighened out all by itself. I notice that the glowplug light does not come on when I turn the key to the run position, but as I turn it further toward the start position it lights, and if I hesitate a few seconds then it starts and when I release the key it goes out. A miracle, I guess.