Glow plugs

[Weedman]

Okay
Last issue. I hope.
Glow plugs work, new controller, new voltage regulator.
I get a volt reading at the glow plugs when ignition is in glow plug position of 12.63 but glow indicator light won't turn off and kubota zd18 won't start.
If I bypass the ignition and heat the glow plugs with a direct wire connection from the battery terminal, the indicator light will turn off and the machine starts.

 

[85Hokie]

You are not getting current to the glow plugs via the turning of the key.

That voltage should drop a good bit as the key is set to the glow plug setting.

How are the plugs wired? Series or parallel?

 

[Vigo]

I agree, 12.63 means basically no current is flowing because the glow plug circuit flows enough it would normally cause a very noticeable drop, maybe down into 11 volts.

I have to suspect you are checking voltage at a different point than where you were jumping power to. If you were using the same point in both cases the only explanation i have is that bad connections are often ‘fixed’ just by finding them, or totally on accident, simply by touching something and therefore disturbing it from the precise spot it had been that was causing the high resistance/open circuit.

 

[Russell King]

Many newer meters can also measure amperage through a wire. ( I am not sure if they can measure DC current since I have never used one for that)

I would see how much amperage is going to the glow plugs

 

[Weedman]

I agree, 12.63 means basically no current is flowing because the glow plug circuit flows enough it would normally cause a very noticeable drop, maybe down into 11 volts.

I have to suspect you are checking voltage at a different point than where you were jumping power to. If you were using the same point in both cases the only explanation i have is that bad connections are often ‘fixed’ just by finding them, or totally on accident, simply by touching something and therefore disturbing it from the precise spot it had been that was causing the high resistance/open circuit.

I am touching the bypass wire to the exact same point as I checked with my volt meter

 

[Weedman]

I agree, 12.63 means basically no current is flowing because the glow plug circuit flows enough it would normally cause a very noticeable drop, maybe down into 11 volts.

I have to suspect you are checking voltage at a different point than where you were jumping power to. If you were using the same point in both cases the only explanation i have is that bad connections are often ‘fixed’ just by finding them, or totally on accident, simply by touching something and therefore disturbing it from the precise spot it had been that was causing the high resistance/open circuit.

 

[Weedman]

Tested each of these points. Apologies for double image

 

[85Hokie]

Tested each of these points. Apologies for double image

What double image?

 

[Weedman]

What double image?

Above in the thread

 

[PoTreeBoy]

Okay
Last issue. I hope.
Glow plugs work, new controller, new voltage regulator.
I get a volt reading at the glow plugs when ignition is in glow plug position of 12.63 but glow indicator light won't turn off and kubota zd18 won't start.
If I bypass the ignition and heat the glow plugs with a direct wire connection from the battery terminal, the indicator light will turn off and the machine starts.

Strange.

Did you download the WSM at KubotaBooks? Assuming the schematic accurately describes your mower, there should be a spring-loaded position between accessory and start that turns on the glow plugs and the light. The light is grounded through the 'combination box' (is this what you're calling the controller?), and I assume that box opens the ground after a certain time, turning off the light. But even if the box fails, the glow plugs heat because they're wired directly to the switch. The plugs should get power in the pre-heat and start positions. Unlike some tractors, your plugs get full battery voltage.

So is the issue when you turn the key to start that the engine doesn't crank, or that it cranks but doesn't start?

Are you having to jumper the starter solenoid to start it? If so, you may have no power or a bad ground at the combination box.

 

[Weedman]

I think I may just install a separate toggle switch directly from the battery yo the glowplug terminal and give up on this problem.

 

[Weedman]

Strange.

Did you download the WSM at KubotaBooks? Assuming the schematic accurately describes your mower, there should be a spring-loaded position between accessory and start that turns on the glow plugs and the light. The light is grounded through the 'combination box' (is this what you're calling the controller?), and I assume that box opens the ground after a certain time, turning off the light. But even if the box fails, the glow plugs heat because they're wired directly to the switch. The plugs should get power in the pre-heat and start positions. Unlike some tractors, your plugs get full battery voltage.

So is the issue when you turn the key to start that the engine doesn't crank, or that it cranks but doesn't start?

Are you having to jumper the starter solenoid to start it? If so, you may have no power or a bad ground at the combination box.

Cranks but doesn't start.
I simply run a wire from the battery to the middle glow plug terminal. When I do this the glow plug indicator light turns on then off and I go and start the tractor. The ignition is turned off when I do this bypass prime.

 

[Dave_eng]

I am not clear what item you are referring to when you say 'new controller."
The key device is called a combination box.
Provide the part number and that will clear up what you are referring to.
The plugs are wired in parallel to answer 85Hokie's question.

The terminal numbers referred to in the operating description are shown in the logic box beside the MAIN SWITCH in the lower right corner of the wiring diagram.
The"pre heat indicator lamp," is controller by the combination box which is why it is important we clarify which items you replaced.

Dave

 

[Weedman]

I am not clear what item you are referring to when you say 'new controller."
The key device is called a combination box.
Provide the part number and that will clear up what you are referring to.
The plugs are wired in parallel to answer 85Hokie's question.

View attachment 118060

The terminal numbers referred to in the operating description are shown in the logic box beside the MAIN SWITCH in the lower right corner of the wiring diagram.
The"pre heat indicator lamp," is controller by the combination box which is why it is important we clarify which items you replaced.

Dave

 

[Weedman]

This is what I'm calling the controller

 

[Weedman]

This is what I'm calling the controller

Prior to replacing this device I was getting no voltage to the glow plugs when the combination was in the preheat position.
I had to turn the machine of manually at the shut off solenoid before this replacement too.

 

[GreensvilleJay]

ok, time for a 'recap'..so we all are on the same 'page'..

if you turn key to preheat, the preheat light comes on ?
if you turn key to 'start' does the starter spin ??

 

[Weedman]

ok, time for a 'recap'..so we all are on the same 'page'..

if you turn key to preheat, the preheat light comes on ?
if you turn key to 'start' does the starter spin ??

Yes to both.

 

[Weedman]

Sorry for the repeats. This forum format is messy with all the ad pop ups. Very annoying.

 

[85Hokie]

Sorry for the repeats. This forum format is messy with all the ad pop ups. Very annoying.

I fixed it !