KH 41

[Rod Desborough]

Looking for readable wiring diagram for KH 41 glow plugs. My old KH 41 has a timed green light when key is turned for the glow plugs. Green light stopped working as did the glow plugs (no starting without GP's). There is a timer for the green light so wondering if the timer is defective does it also affect the glow plugs?

 

[Roadworthy]

Put a meter or an indicator light on one of the glow plugs. If they're getting power you'll get an indication.

 

[Henro]

Looking for readable wiring diagram for KH 41 glow plugs. My old KH 41 has a timed green light when key is turned for the glow plugs. Green light stopped working as did the glow plugs (no starting without GP's). There is a timer for the green light so wondering if the timer is defective does it also affect the glow plugs?

It might not be a bad idea to verify with a meter that indeed you are not getting voltage to the glow plugs, as Roadworthy suggested. Just to verify that your initial analysis is correct.

Sounds like you may have an electrical control issue as you suspect. Hope you can find a wiring diagram. Hard to speculate without knowing anything about your excavator. I was able to find an electrical diagram for my KX41 on line somewhere. Maybe you can get lucky too if you search a bit...

 

[Rod Desborough]

Thanks for all the input. Glow plugs are ok as is the wiring to them. I was able to confirm that the lamp timer is also a relay for the glow plugs and is wired in series with the glow plugs so if the lamp does not come on the plugs don't get power. A new timer relay is on it's way. In the meantime heated air into the air intake from an old hairdryer did a good job as a starting aid.

UPDATE A new timer relay for the glow plug light and glow plugs did not fix the problem. Now considering a starter typ 15a rated button to provide 12v directly to the glow plugs. Glow plugs energized by the non latching push button - plan is to hold it on forthe 3-4 seconds before release and then cranking. Thoughts welcome. This is on a very old KH 41 with over 4600 hours but still has use for me. I can start it with a hair dryer preheating intake air but would prefer the push button solution for the glow plugs.

 

[Henro]

....A new timer relay is on it's way. In the meantime heated air into the air intake from an old hairdryer did a good job as a starting aid.

That’s thinking outside the box!

It would never have occurred to me to try that. Will file that away for the future.

 

[Rod Desborough]

I'm very sure my JD 3020 Yanmar engine has an air heater start assist and has never let me down in 14 years of Canadian winters. The old Kubota KH 41 with +4600 hours wasn't as happy starting on the hair dryer as glow plugs but hair dryer dot the job done. When I was looking for info re glow plugs I came across a nice write up of current day diesel start assist methods and the air pre heater was the winner especially for larder engines in pusher type RV's so the thinking outside the box idea was not quite an original idea -using the hair dryer was. however.

 

[GreensvilleJay]

1) go here

Index of Kubotabooks/Excavators/

2) download the PDF...
3) check out page 313 (rotate right 90*) then print it ..

any problems, email me ,I'll figure a way to send the diagram...
Jay

 

[Rod Desborough]

1) go here

Index of Kubotabooks/Excavators/

2) download the PDF...
3) check out page 313 (rotate right 90*) then print it ..

any problems, email me ,I'll figure a way to send the diagram...
Jay

Thanks for the reference.
I had found that diagram somewhere else but it was unreadable when trying to trace the wiring but the reference you provided is much cleaner and easy to follow.

 

[Rod Desborough]

A new timer relay for the glow plug light and glow plugs did not fix the problem. Now considering a starter typ 15a rated button to provide 12v directly to the glow plugs. Glow plugs energized by the non latching push button - plan is to hold it on forthe 3-4 seconds before release and then cranking. Thoughts welcome. This is on a very old KH 41 with over 4600 hours but still has use for me. I can start it with a hair dryer preheating intake air but would prefer the push button solution for the glow plugs.

 

[GreensvilleJay]

seems fine to me as my BX23S glowplugs get heated that way,every time, year round.. so far 3 yrs/501 hrs... always starts.
I have no idea why the new timer didn't work for you.
friend has a KH41, lotta hours as well(sloppy turning lefty-righty.....)

 

[GeoHorn]

Brand New Parts can be installed..... and they be bad. BTDT

 

[Rod Desborough]

seems fine to me as my BX23S glowplugs get heated that way,every time, year round.. so far 3 yrs/501 hrs... always starts.
I have no idea why the new timer didn't work for you.
friend has a KH41, lotta hours as well(sloppy turning lefty-righty.....)

I don't think it is the timer /relay. suspect wiring between the control panel and the engine compartment - wiring looks sketchy/suspect. My old KH41 pretty sloppy as well but big $'s to restore so will keep it going as long as I can get some work out of it.

 

[kubotasam]

. Now considering a starter typ 15a rated button to provide 12v directly to the glow plugs. Glow plugs energized by the non latching push button - plan is to hold it on forthe 3-4 seconds before release and then cranking.

A push button controlling a relay, then to the glow plugs could be a more permanent solution. Not sure if the switch would handle the amperage draw. Hold the glow plugs on while cranking the engine to start it. That is what a proper operating glow plug system does.

 

[Rod Desborough]

A push button controlling a relay, then to the glow plugs could be a more permanent solution. Not sure if the switch would handle the amperage draw. Hold the glow plugs on while cranking the engine to start it. That is what a proper operating glow plug system does.

The KH41 has a timer relay that the light comes on when keyturmed to glow plug position andwhenthe light times out you go to crank and away she goes. Would a 15amp rated switch now work without a relay??

 

[PoTreeBoy]

The KH41 has a timer relay that the light comes on when keyturmed to glow plug position andwhenthe light times out you go to crank and away she goes. Would a 15amp rated switch now work without a relay??

Your problem should be fairly straight forward, assuming
1. The diagram in the WSM is correct and
2. I'm correct in assuming that you turn the key switch backwards (counterclockwise) to preheat.
The preheat light is advisory only - the timer only actuates the light and doesn't control the glow plugs. Here's what I'd do:
1. Remove the small wire (or the big one) from the starter solenoid so the machine won't start.
2. With the switch off, use a tester or light to find the battery connection on the switch. Probably a heavy red wire. No other terminals should show voltage.
3. With the key turned back to the left, one terminal (besides the battery connection) should show 12 volts. If not, the switch must be bad. Is so, there must be a bad wire or connection between there and the glow plugs. Trace that wire to the glow plugs until you find the break. (Or run a new wire) There should to be 2 connectors between the switch and gp's, but no relay.

I'm betting it's the keyswitch. If that contact is bad, the glow plugs won't work and the light won't come on (you have tested the bulb, haven't you?).

 

[Rod Desborough]

Your problem should be fairly straight forward, assuming
1. The diagram in the WSM is correct and
2. I'm correct in assuming that you turn the key switch backwards (counterclockwise) to preheat.
The preheat light is advisory only - the timer only actuates the light and doesn't control the glow plugs. Here's what I'd do:
1. Remove the small wire (or the big one) from the starter solenoid so the machine won't start.
2. With the switch off, use a tester or light to find the battery connection on the switch. Probably a heavy red wire. No other terminals should show voltage.
3. With the key turned back to the left, one terminal (besides the battery connection) should show 12 volts. If not, the s. It seems odd that the light stops working at the same time no glow plugs howevewitch must be bad. Is so, there must be a bad wire or connection between there and the glow plugs. Trace that wire to the glow plugs until you find the break. (Or run a new wire) There should to be 2 connectors between the switch and gp's, but no relay.

I'm betting it's the keyswitch. If that contact is bad, the glow plugs won't work and the light won't come on (you have tested the bulb, haven't you?).

Thanks for the above procedure. The bulb is good. Yes , key goes CCW forglow plug and indicator light than when all working correctly, goes out after 3-4 seconds. Switch was replaced 2-3 years ago so relatively new compared to the machine. From what you describe I could run a new 12 or 10 gauge wire from the CCW contact on the switch if it shows 12volts , direct to the glow plugs, no relay required. There 5 terminals in the timer-relay so it would be good to have a wiring diagram as to what goes to each terminal - I need more time and better glasses to follow wiring diagram.

 

[PoTreeBoy]

Thanks for the above procedure. The bulb is good. Yes , key goes CCW forglow plug and indicator light than when all working correctly, goes out after 3-4 seconds. Switch was replaced 2-3 years ago so relatively new compared to the machine. From what you describe I could run a new 12 or 10 gauge wire from the CCW contact on the switch if it shows 12volts , direct to the glow plugs, no relay required. There 5 terminals in the timer-relay so it would be good to have a wiring diagram as to what goes to each terminal - I need more time and better glasses to follow wiring diagram.

Do you know why the keyswitch was replaced the first time? If it was for the same problem, you could add a higher current relay in the preheat circuit to reduce the load on the switch.
If you do run a new wire, you need to know there is another wire off the switch to the glow plugs. It comes off a terminal that is hot when the switch is in 'start' to provide preheat while the starter is engaged. I assume these 2 wires are jumpered together near the switch. A smaller wire from this wire runs to the timer and one terminal of the bulb. Note there are only 4 terminals on the timer, but these 2 may be jumpered together in the connector giving 5 wires.
The other 3 wires on the timer are:
Ground (black)
Bulb (white)
Starter solenoid (color?, I assume this is what keeps the bulb off while cranking)
Hope this helps. Sometimes on that schematic it's hard to tell if crossing wires are connected or just crossing.

 

[Rod Desborough]

Your problem should be fairly straight forward, assuming
1. The diagram in the WSM is correct and
2. I'm correct in assuming that you turn the key switch backwards (counterclockwise) to preheat.
The preheat light is advisory only - the timer only actuates the light and doesn't control the glow plugs. Here's what I'd do:
1. Remove the small wire (or the big one) from the starter solenoid so the machine won't start.
2. With the switch off, use a tester or light to find the battery connection on the switch. Probably a heavy red wire. No other terminals should show voltage.
3. With the key turned back to the left, one terminal (besides the battery connection) should show 12 volts. If not, the switch must be bad. Is so, there must be a bad wire or connection between there and the glow plugs. Trace that wire to the glow plugs until you find the break. (Or run a new wire) There should to be 2 connectors between the switch and gp's, but no relay.

I'm betting it's the keyswitch. If that contact is bad, the glow plugs won't work and the light won't come on (you have tested the bulb, haven't you?).

Your problem should be fairly straight forward, assuming
1. The diagram in the WSM is correct and
2. I'm correct in assuming that you turn the key switch backwards (counterclockwise) to preheat.
The preheat light is advisory only - the timer only actuates the light and doesn't control the glow plugs. Here's what I'd do:
1. Remove the small wire (or the big one) from the starter solenoid so the machine won't start.
2. With the switch off, use a tester or light to find the battery connection on the switch. Probably a heavy red wire. No other terminals should show voltage.
3. With the key turned back to the left, one terminal (besides the battery connection) should show 12 volts. If not, the switch must be bad. Is so, there must be a bad wire or connection between there and the glow plugs. Trace that wire to the glow plugs until you find the break. (Or run a new wire) There should to be 2 connectors between the switch and gp's, but no relay.

I'm betting it's the keyswitch. If that contact is bad, the glow plugs won't work and the light won't come on (you have tested the bulb, haven't you?).

If it is not the switch and from what you said, I could go from the switch terminal that shows 12 v when turned CCW to a new push button, no latching, on the control panel and from that switch to the gloow plugs all using 10 or 12gauge wire, When I turn the switch CCW and push the button for 3=5 seconds at the same time and then go to crank I should be good. No relay, resistor required in the new circuit from switch to plugs?
You sure seem to know the KH41 , that's great since not many do for a machine that age. I purchased it used 17 years ago and have managed to keep it working.

 

[PoTreeBoy]

If it is not the switch and from what you said, I could go from the switch terminal that shows 12 v when turned CCW to a new push button, no latching, on the control panel and from that switch to the gloow plugs all using 10 or 12gauge wire, When I turn the switch CCW and push the button for 3=5 seconds at the same time and then go to crank I should be good. No relay, resistor required in the new circuit from switch to plugs?
You sure seem to know the KH41 , that's great since not many do for a machine that age. I purchased it used 17 years ago and have managed to keep it working.

Well, uh, no, I don't know anything about a KH41 except what I see on that wiring diagram somebody posted above.
But yeah running the wire like you described should work, but you don't need to add a push button switch. Make sure the jumper between the two connections on the keyswitch stays there so you'll have glow plug power while the starter is engaged.
This won't fix the timer/light issue, of course.