flat battery on kubotaL4200

[Luath]

Hi Dave,

I think the battery has been draining because of power being drawn by the glow plugs. The orange light on the dashboard comes on intermittently when the tractor is running, it does not light up when I start the tractor in warm weather (the temp in the drive shed is about 25C at the moment) I've tried the tester and it glows as expected across the battery and when hooked up to the starter. No response from any of the four glow plugs when engine off, key turned or engine on. The plugs (unless I'm looking at the wrong components?) have small nuts on top and are joined together by a metal strip that seems to have a coating of plastic insulation between the plugs. I've used the probe at the top of each small nut and further down the plug just above the larger hex nut.
Your thoughts would be greatly appreciated.

Cheers Luath.

 

[Dave M7040]

luath
Next thought would be to connect the alligator clip to one of the small nuts on one of the glow plugs and keep the probe in the tractor with you pressed to a ground such as anything metal. If the light in the probe comes on when the orange light on the dashboard comes on then power is being supplied briefly to the glow plugs. I doubt that you will find this is happen which means a couple of things. One is that the glow plug controller is going bad and Two there is another reason the battery is being drained. A failing alternator can have a failed diode which allows current to flow to ground.
Do this next test and report back
Dave

 

[Dave M7040]

luath
Next thought would be to connect the alligator clip to one of the small nuts on one of the glow plugs and keep the probe in the tractor with you pressed to a ground such as anything metal. If the light in the probe comes on when the orange light on the dashboard comes on then power is being supplied briefly to the glow plugs. I doubt that you will find this is happen which means a couple of things. One is that the glow plug controller is going bad and Two there is another reason the battery is being drained. A failing alternator can have a failed diode which allows current to flow to ground.
Do this next test and report back
Dave

 

[skyhook]

Dave..I think he stated that he has already replaced the glow plug relay.
The ignition switch also sends power to the relay, could be shorting out internally at times, but at that temp, I don't see why the plugs would even turn on.
If you have a "volt meter", ground one end and tap into a live circuit with the other to monitor voltage when the tractor is off and when it's running, with that little alternator, you should be getting around 13 or so volts, running.
You should see a drastic decrease when and "if" the glow plugs come on while running.
The dash light for the glow plugs coming on "intermittently" tells me they are, so something is telling the controller to light them up, "if" you've already changed it, then it's getting a signal from somewhere,
if they are coming "on" at times when they shouldn't, this will definitely put a strain on your battery, especially if you have any other accessories running also.

 

[Luath]

Hi Chaps,

Fired up the tractor this morning and left it idling. Checked fro time to time until (about an hour later) the orange light was on. Circuit tester from glow plug to brake pedal and light came on. The orange light went off and the circuit tester gave no further response. Unfortunately there was no time to get a meter reading from the glow plug. I used the meter across the battery and it indicated 14.33V with the engine idling.

I have had occasions while using the tractor when the glow plug warning light has been on for prolonged spells, I guess this is the reason for battery drain. Tractor has flashers and three working lights, all rarely used. No other electrical take off as far as I know.

Any thoughts upon the next step?

Cheers, Luath

 

[Dave M7040]

Luath
Do you have a wiring diagram you could post?
You said you replaced the glow plug relay but I am wondering if there is also a controller which determines how long the glow plugs are powered.
From your most recent post, if I understand correctly, the test light confirmed power to the glow plugs at the same time the dash light was on and further showed no power to glow plugs when dash light was off.
Is this correct?
Dave

 

[Yamaha2112]

Check the alternator bracket. I had the same problem and tried EVERYTHING only to find out later it was snapped and couldn't provide enough belt tension. It looked ok until I got close. Couldn't believe it when I saw it.

 

[skyhook]

You must have an upgraded alt to be putting out that voltage, when you put the test light on the glow plug and grounded it to the brake pedal, you said the glow plug light went out....
This tells me you have a bad ground somewhere in that circuit, ( because when you used your test light, you essentially created a ground in that line,), check your ground wires, the relay or controller for the glow plugs is not receiving a signal to shut off, or at times it is etc....

 

[Dave M7040]

You must have an upgraded alt to be putting out that voltage, when you put the test light on the glow plug and grounded it to the brake pedal, you said the glow plug light went out....
This tells me you have a bad ground somewhere in that circuit, ( because when you used your test light, you essentially created a ground in that line,), check your ground wires, the relay or controller for the glow plugs is not receiving a signal to shut off, or at times it is etc....

Skyhook
Not trying to be argumentative but perhaps the test I ask Luath to do was not adequately described and may have mislead you.
I was having him check for voltage at the glow plugs WHEN the dash light came on to confirm that not only was the dash light coming on but power was being supplied to the glow plugs in the same intermittent fashion that the dash light was operating. The testing confirmed that was happening.

My next conclusion, since he said he replaced the glow plug relay, was to wonder if there was an additional component, perhaps called a glow plug controller, which received temp signals from the engine and decided how long and if the glow plugs needed to be energized.

The test light was not providing a ground path.

Hope this makes more sense now.

Dave M7040

 

[skyhook]

No problems Dave, I do believe there are two for the glow plug system, if I recall..,
A relay and a controller but just can't say positively, when I sold mine i also sold the repair manual for it.
I am wondering why the dash light went out when he applied the test light to the plug, my thinking is that the light provide a path of resistance to ground informing the controller it was time to shut off, hence a ground problem around the controller or relay.
I could be way off base on this, but it's the way i think....lol