Topics

thermo start plug disaster


 

Hi guys had a bit of a problem having replaced the thermo glow plug on my YM1502D
The replacement unit i obtained short circuited the first time i used it causing the wiring to smoke until i managed to turn it off.
Now when I go to start it (re-installed the old glo plug) the lights on the dashboard dont work in the run position but do in the start crank position
These include the ignition and oil pressure light ,the fuel gauge and the headlamps and indicators.
The tractor starts and runs but as soon as the key returns to the on position the fuel gauge stops working.
ALL the fuses in the box on the LHS of the steering column are intact and working
So my question is  :-      is there another set  of fuses under or behind the dashboard (or aywhere else) that could be responsible for this .Is there a relay that I may have burnt out ?
Or does anyone have any experience of a similar issue and can suggest a fix for me .
The replacement unit was shorting against its own body I think as the terminal was badly bent when i got (i thought this was as it should be) but testing it after the event found it to be faulty.
too late for my lights though.
Any help would be appreciated
drossy57


KC2GIU
 

Doug, 

Your YM1502D has no direct manual, but a few other models to give CLUES.  Last year, our community put together an extensive YM 3-digit series Electrical diagram compiled manual.  I would suggest grabbing that for now and do a comparison to the YM1501 and others.  

It's been a tad harder finding manuals.  In the past week only the YM2000B and YM2000BZ were found.  We are still poking around. And even the community donates or shows where to grab a few. :) 

You may have to open up the dash.  Look for fried wires.  Look at the VR (Voltage Regulator) unit. etc.  

Send in the next message what your bulbs look like.  There are 3 or so styles with our YM series.  My last set came from NAPA. 
 
Steve 


Bill Pendergrass
 

While I don't have a schematic or my own similar tractor handy to look at, I'll try my best to help.  My vote is on the keyswitch internal contacts or wipers.  I dont remember a relay under my dash. Instrument lighting loads don't normally use one. Relays are used to allow a small switch to control a large load.  Headlights would be one. The glow plug would be another.  But....if no relays, the high loads go through the ignition switch itself.  Did the keyswitch get hot perhaps? Might not know since the contacts are burried pretty deep in a big switch body.


Bill Pendergrass
 

Doug,
I may have just been looking at the combined 3 digit manual Steve was talking about. I see a 3 terminal main switch arrangement that could do what you describe. The lights AND the glow plug come off the same main switch  terminal.  You have a second switch to activate the glow plug right?  It is electrically inbetween the main switch and the glow plug.

So..main switch is in ON position. Activate glow plug. All heck breaks loose and you grab for switches until it turns off.    The short circuit has passed through the main switch, through the glow plug switch and on to the glow plug.

The main switch is damaged.  In addition to no lights, you should have no glow plug power either, while the internal main switch wiper is in the ON position.  The internal wiper is a hockey stick shaped arc.  The end of the stick gets battery power from a center contact and the blade distributes it to the right screw terminals. That arc shaped wiper stays in contact with the lights and glow plug terminal as its tip moves towards the start terminal.  Part of that arc shaped piece of copper is burned.  Not all the way through, but enough to insulate it from the mating ON terminal while in the ON position.

If you cant find an exact replacement, I could help you replace it with a 3 position toggle switch to include the start function as a spring loaded momentary UP position.   Alternatively a plain 2 position toggle and push button start.


KC2GIU
 

Doug, 

Went thru the models to find models with a 3T72 Series engine.  Typically, this would lend clues towards a schematic. 
Gray YM - - - YM1401, YM1410, YM1510
US market YM - - - YM169, YM180, YM186, YM187
YM in green paint - - - JD670, JD755 (Get TM1360 and look at pg -450. in the manuals section) 

Grab this too out of the manuals section. 
YANMAR ELECTRICAL SCHEMATICS YM 3-DIGIT MODELS R3.pdf

I like Bill suggestions too.  

Steve 


 

thanks guys some great info
will check to see if any feed at anytime to glow plug now
ill do that then see if i can remove and replace the ignition barrel switch.
If not Bill you may have to talk me through the toggle switch options
Im generally ok with mechanics but not so good with electrics but willing to learn
Ill keep you informed
Thanks
Doug


J Z
 

We should always be ready to learn. Even at 76 (I would be 77 but was sick a year ). I love learning new things. 

On Wednesday, March 24, 2021, 08:15:26 AM CDT, <drossy57@...> wrote:


thanks guys some great info
will check to see if any feed at anytime to glow plug now
ill do that then see if i can remove and replace the ignition barrel switch.
If not Bill you may have to talk me through the toggle switch options
Im generally ok with mechanics but not so good with electrics but willing to learn
Ill keep you informed
Thanks
Doug


Wally Plumley
 

Just for curiosity...

The initial post was titled "thermo start plug disaster", but all of the discussion has been about a glow plug. These are two different things. As I understand it:

"Glow plugs" are electric heaters (one per cylinder) used to warm the combustion chambers to make starting a cold Diesel a little easier. The glow plugs are used before spinning the engine over.

"Thermostart" is a Yanmar system that dribbles a little Diesel fuel over a single electric heating element to generate hot Diesel fuel vapors in the intake manifold just before and as the engine starts to spin. In conjunction with the compression release, this usually makes the Yanmar Diesel start very well indeed in cold temperatures.

Which system does Doug's tractor actually have? Either one could have a serious short-circuit in the starting system.

Wally


On 3/24/2021 9:18 AM, J Z via groups.io wrote:
We should always be ready to learn. Even at 76 (I would be 77 but was sick a year ). I love learning new things. 

On Wednesday, March 24, 2021, 08:15:26 AM CDT, <drossy57@...> wrote:


thanks guys some great info
will check to see if any feed at anytime to glow plug now
ill do that then see if i can remove and replace the ignition barrel switch.
If not Bill you may have to talk me through the toggle switch options
Im generally ok with mechanics but not so good with electrics but willing to learn
Ill keep you informed
Thanks
Doug


Scotty
 

Yeah, I think there has been some misuse of language here. Wally, your definitions are the same as all mechanics use - certainly the same ones I use. Although in this thread the posters seem to be calling the heating element in theThermostart device a "glow plug". Where as you point out that isn't what mechanics tend to mean when the say "glow plug". But it does make a certain amount of sense. The heating element in theThermostart device does use electricity and it does glow red hot. 

But we can adapt to language. What I think will be a lot more difficult is trying to troubleshoot an electrical system without a VOM and good understanding of how it is used. Old Yanmars have a very simple electrical system. I'd bet that a mechanic with a Volt/Ohm/Meter could find the problem in half an hour....max. But without the VOM I wouldn't even know where to start. Trial and error? Replace things at random? 
rScotty


On Mar 24, 2021, at 9:11 AM, Wally Plumley <wplumley@...> wrote:

Just for curiosity...

The initial post was titled "thermo start plug disaster", but all of the discussion has been about a glow plug. These are two different things. As I understand it:

"Glow plugs" are electric heaters (one per cylinder) used to warm the combustion chambers to make starting a cold Diesel a little easier. The glow plugs are used before spinning the engine over.

"Thermostart" is a Yanmar system that dribbles a little Diesel fuel over a single electric heating element to generate hot Diesel fuel vapors in the intake manifold just before and as the engine starts to spin. In conjunction with the compression release, this usually makes the Yanmar Diesel start very well indeed in cold temperatures.

Which system does Doug's tractor actually have? Either one could have a serious short-circuit in the starting system.

Wally


On 3/24/2021 9:18 AM, J Z via groups.io wrote:
We should always be ready to learn. Even at 76 (I would be 77 but was sick a year ). I love learning new things. 

On Wednesday, March 24, 2021, 08:15:26 AM CDT, <drossy57@...> wrote:


thanks guys some great info
will check to see if any feed at anytime to glow plug now
ill do that then see if i can remove and replace the ignition barrel switch.
If not Bill you may have to talk me through the toggle switch options
Im generally ok with mechanics but not so good with electrics but willing to learn
Ill keep you informed
Thanks
Doug



 

Thanks Wally 
Well spottedjust calling it gliwplug for ease 

It is a thermo switch on this model 
Doug


 

Update from today 
Feed at thermo switch with ignition in start position no feed to switch in ON position
Replacement unit definitely shorting our so clean installed and bled old unit as suggested 
Starts ok a bit slow but gets there so initial problem is still with me. Noticed lights on dash come on in imposition of you jiggle the key so looks like an ignition barrel burnt thing
New thermo switch on the way just hope it's the right one 
Doug


Bill Pendergrass
 

Doug,
Hoye tractor has a replacement and instructions. Look at their web site.

Wally and Scott,
A high current heater is a high current heater no matter the name. I intentionally continued to use glow plug because the OP started that way. I was communicating with him, not everybody else.  The assumption is that the experienced members would realize the difference and take it in stride.


 

Thanks Bill 
Based in the UK so sometimes postage and import duties make buying from Hoye costly but I'll take a look
Thanks for your understanding
Doug


Bill Pendergrass
 
Edited

Right,
That's a little twist. Hoye is asking roughly $40 US so that might become a hard pill to swallow once delivered to the UK.   I traveled there a lot while working for TetraPak and making milk bottle production lines for Wisemans Dairies from London to Glasgow.  Enjoyed those years greatly.  Closest work to Nottingham was in Ashby-de-la-Zouch.

Try searching for a Honeywell 2TL1-50 Toggle switch from a UK based industrial electronics supplier. That switch is roughly 20 quid here.  If you strike gold, I will send a wiring sketch to do the off - on - start thingy.  You will still need a functioning Theeermooostart switch. A 1TL1-2 or -3 could replace it if needed.


Wilhelm Derner
 

Hoye wanted $65 to ship a manual to me here in the UK so I'm sure a part will be more money. Have you tried Beckside Machinery in Market Rasen?

On Thursday, 25 March 2021, 01:27:28 GMT, Bill Pendergrass <rzbill@...> wrote:


Right,
That's a little twist. Hoye is asking roughly $40 US so that might become a hard pill to swallow once delivered to the UK.   I traveled there a lot while working for TetraPak and making milk bottle production lines for Wisemans Dairies from London to Glasgow.  Enjoyed those years greatly.  Where are you if you dont mind sharing?

Try searching for a Honeywell 2TL1-50 Toggle switch from a UK based industrial electronics supplier. That switch is roughly 20 quid here.  If you strike gold, I will send a wiring sketch to do the off - on - start thingy.  You will still need a functioning Theeermooostart switch. A 1TL1-2 or -3 could replace it if needed.

--
Wil Bear.


 

Thanks Wilhelm
No I haven't but I will 
Good info


Bill
Ashby is not far and I have been many times with work in the past
Doug


BMaverick
 

Doug,

Some of the Yanmar ignition switches are common.

We have a few of these Yanmar MEM documents when we found the YM 4-digit manuals months back.  The attached is an ignition switch from a YM1301.  Looks like an upgrade is recommended.  These are Yanmar drawings too.

Hoye, Fredricks and other parts suppliers show to use newer style VRs.  Well, there is another MEM from Yanmar showing exactly that years prior.

BMaverick
 
--
Yanmar Tractor Owners Group.  A valuable source for owners of Yanmar tractors.