L4200 Glow Plugs

[Firefighterontheside]

Can anyone tell me what parts I should replace to hopefully get my glow plugs to work? The light doesn’t come on and it’s hard to start when it’s cold. Do I need a relay? Thanks.

 

[Fordtech86]

I think you need a wiring diagram and a multimeter to start with

 

[Firefighterontheside]

Well, I have the meter, but don’t know what to check. Guess I would need a service manual.

 

[North Idaho Wolfman]

Sent you a link Via Email for the WSM.

 

[Firefighterontheside]

Got it! Thanks Wolfman. Had to look in my junk mail to find it. I have saved it to my iPad.

 

[johndeerebones]

I know it is an old thread, but your tractor "reads" engine temp etc and the glow plug controller (really its name) and it engages them based on its ideals. No user input available. I took the dash apart and used a momentary switch to engage the relay myself, net cost the switch, had everything else. You can put a controller for $70 or so too...

 

[Dave_eng]

I know it is an old thread, but your tractor "reads" engine temp etc and the glow plug controller (really its name) and it engages them based on its ideals. No user input available. I took the dash apart and used a momentary switch to engage the relay myself, net cost the switch, had everything else. You can put a controller for $70 or so too...

On the M series there is a trick to override the GP controller. There is likely a trick for the L series also.

The following is a cut and paste from an old thread
Kubota glow plug operation

In very cold weather, with the block heater plugged in, the glow plug sensor will lock out the glow plugs as it senses a warm engine.

However, starting, in these circumstances can be rough and worrisome as the engine is still inhaling very cold air.

The trick is to put the shuttle shift lever in forward and turn the key to the start position.

You will hear a relay click on. I count to 10, put the shuttle back into the neutral position and start the engine.

Makes an amazing difference.

On newer models, M7060 perhaps, Kubota realized the problem and provided software which would allow the dealer to set which sensor decided the GP on time. When owners of the M series tractors install their own block heater, they won’t get the software change and need to use the manual way to control the GP’s

I know there are GP work around on other Kubota models but I was only interested in M7040’s at the time.

I learned of this undocumented feature from a Kubota mechanic who was moving around many machines for snow clearing. It was very cold and the fact that he had no trouble getting them to fire caught my eye.

Dave

 

[200mph]

If they are going to test the circuit, a voltage drop test can be very helpful in finding issues with the circuit.

Unlike a static voltage test, the circuit is tested under load with a voltage drop test. There are many videos available if uncertain how to perform.