Nagging Electrical Starting Problem on YM186D

[markey-HT]

I have been living with this issue for a while. When engine is cold, 90% of the time the solenoid works fine and starter works. When it does not work, I must keep turning the key to start a few times because the solenoid doesn't completely pull-in. After that, it eventually works. However, when hot, I don’t even get a “click” sound from solenoid. When this occurs, to start engine, I must run wire from positive battery terminal directly to the 12V solenoid terminal in order to start engine. Here is what I have tested:

1. Pulled ignition switch, tested fine.
2. Voltage to 12v solenoid wire is only 11.6 v (too low) when ignition switch is in “start” position.
3. When I disconnect thermostart coil wire and test 12v solenoid wire as above, it reads 12.6, which is fine. (Thermostart coil is always activated when key is moved to “start” position. The chamber gets warm.) Obviously, the thermostart is pulling too much current and not leaving enough for the solenoid. When I leave the thermostart wire disconnected and connect up the 12v solenoid wire to the solenoid, turn key to “start”, everything works properly.
4. Sounds like battery, right? However, battery reads 12.7v and passes load test at all times. Battery is only 2 years old. I know that when wires heat up, as in hot engine, the resistance increases. Thus, the starting issue when engine is hot. The battery is 450 CCA. Does it need higher CCA???

 

[Aaron-HT]

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Are you talking about just a small 'trigger' wire to the small terminal on the solenoid or a large cable to the big lugs on the solenoid? A, B, or C?
https://www.hoyetractor.com/starter-test.htm

<QUOTE><s>

</e></QUOTE>

No. Since it will start when using the wire (to the same battery) then the problem is not your battery.

I'm curious what your voltage reading at the small wire (B) on the solenoid is when the tractor is warm and the starter will not do anything.
https://www.hoyetractor.com/starter-test.htm

My guess is that you just have a bad connection (fuse box?) or maybe an ignition switch with crusty contacts. Remember that 'testing fine' with no load is not the same as 'working in the real world'. You might have a good enough connection to get 12vdc at 0 amps (volt meter/ test light) but might end up with almost no volts when there is a draw (like the solenoid).

 

[markey-HT]

<QUOTE author="Aaron"><s>

</s><QUOTE><s>

</e></QUOTE>

Are you talking about just a small 'trigger' wire to the small terminal on the solenoid or a large cable to the big lugs on the solenoid? A, B, or C?
https://www.hoyetractor.com/starter-test.htm

<COLOR color="#FF0000"><s></s>I run a small trigger wire from battery positive to small terminal on solenoid. This activates ONLY the solenoid and starter, not the thermostart glow plug.<e></e></COLOR>

<QUOTE><s>

</e></QUOTE>

No. Since it will start when using the wire (to the same battery) then the problem is not your battery.

<COLOR color="#FF0000"><s></s>Remember that when using the small wire from positive battery pole to small solenoid terminal, I am bypassing the extra load (thermostart coil) that would have occurred when using the "start" on the ignition switch.<e></e></COLOR>

I'm curious what your voltage reading at the small wire (B) on the solenoid is when the tractor is warm and the starter will not do anything.
https://www.hoyetractor.com/starter-test.htm

<COLOR color="#FF0000"><s></s>Yes, that is next on my to-do list. I am guessing it will be lower.<e></e></COLOR>

My guess is that you just have a bad connection (fuse box?) or maybe an ignition switch with crusty contacts. Remember that 'testing fine' with no load is not the same as 'working in the real world'. You might have a good enough connection to get 12vdc at 0 amps (volt meter/ test light) but might end up with almost no volts when there is a draw (like the solenoid).<e>

/s>I think that the battery's current is being consumed by the thermostart glow plug which is always energized at the same time as the solenoid when turning the key to the "start" position. Doing this normal operation does not leave enough current to fully energize the solenoid. In this normal operation if I disconnect the wire to the thermostart plug, that leaves sufficient battery current to fully energize the solenoid/starter.<e>[/color]</e></COLOR>

 

[winston-HT]

I have read of this same problem on several other tractor manufacturers. Some install starter assist relays. If not to difficult I would run a new and larger wire from the switch to the solenoid. You are loosing current somewhere, likely old connections.

 

[Aaron-HT]

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Not normal. There is a bad connection somewhere.

 

[markey-HT]

I think that the "bad connection" lies in the original existing "thin" wire that runs from the ignition switch to the solenoid via the safety switches. It apparently is not carrying sufficient current to allow proper and consistent operation of the solenoid. Sometimes I hear the solenoid "clicking" when I attempt to "start", however, it must not be banging the internal solenoid contacts with sufficient force. To the "C" terminal on the ignition switch is connected a "thin" solenoid wire (which after the ignition connection, apparently goes to the two safety switches then on to the solenoid) plus a low voltage lamp check relay. All other wires to the switch are heavier gauge. The easy fix would be to directly wire a heavier 12 gauge wire from the ignition switch directly to the solenoid. The big downside in doing that is I will be bypassing the two safety switches.

 

[winston-HT]

Yep, that circuitry of wires is why some have used the start relay.

 

[Norm-HT]

You have eliminated the starter and the battery. Io nothing obvious shows up by troubleshooting I would replace the ignition switch.next.

 

[markey-HT]

<QUOTE author="Norm"><s>

</s>You have eliminated the starter and the battery. Io nothing obvious shows up by troubleshooting I would replace the ignition switch.next.<e>

/s><U><s></s>may<e></e></U><e>[/i]</e></I> fix the issue. I would rather replace the ignition switch if that would fix the issue, but I hate to unnecessarily throw parts in.

 

[Aaron-HT]

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</e></QUOTE>

The thermostart is pulling too much current for the bad connection to provide. Fix the bad connection and you will fix the problem. You could eliminate the wiring up to the ignition switch as a possible problem by temporarily running your +12v wire right to the 'B' terminal on the switch. If you still get a voltage drop then it would almost guarantee the ignition switch was the cause since the glow plug and starter circuit part ways after that. If the voltage drop goes away then you know it is a bad connection between the battery and the switch.

 

[markey-HT]

I performed a new test. The battery voltage at rest is 12.7v
The heavy gauge wire that connects to terminal B on ignition switch comes from the + battery, and is always powered.
At rest, the voltage readings match -- 12.7v at battery, and 12.7v at terminal B

Now, when moving key to "start" which places load due to glow plug and warning lights, the voltage at the battery drops to 12.3v while the voltage at terminal B drops to 12v. Under load, all other terminals (including C terminal which powers solenoid) on ignition switch match the voltage at B terminal (12v). This test removes the safety switches out of the equation.

UNDER LOAD:
When working properly, shouldn't the voltage at the ignition terminals match the the voltage at the battery when the key is in start position and under load?

UNDER LOAD:
Could bad internals of the ignition switch be causing the voltage drop discrepancy (12.3v vs 12v) between the battery and the ignition terminals when under load? OR could the heavy gauge B wire be defective when under load?

 

[markey-HT]

<QUOTE author="Aaron"><s>

</s><QUOTE><s>

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The thermostart is pulling too much current for the bad connection to provide. Fix the bad connection and you will fix the problem. You could eliminate the wiring up to the ignition switch as a possible problem by temporarily running your +12v wire right to the 'B' terminal on the switch. If you still get a voltage drop then it would almost guarantee the ignition switch was the cause since the glow plug and starter circuit part ways after that. If the voltage drop goes away then you know it is a bad connection between the battery and the switch.<e>

/e></QUOTE>

I followed this advice and disconnected + battery cable and disconnected heavy gauge B terminal wire at the ignition switch. Doing this takes the heavy gauge wire out of the equation. I got a scrap heavy gauge wire and connected to the + battery and the B ignition terminal. With NO load, both voltages at terminal B and the + battery did match (12.7v). However, when under load, there was the same voltage drop at ALL ignition switch terminals. The drop while under load was 12.4 at battery vs 11.9 at all ignition terminals.

Verdict??? Internals of the switch are bad?

 

[winston-HT]

Noting the wiring for the thermostart shown here why don't you remove the start position glow plug wire from the switch and use only the thermostart position for it. You really don't need it to be working while cranking. At least that is my opinion. https://www.hoyetractor.com/is52110-inst.jpg

 

[markey-HT]

<QUOTE author="winston"><s>

</s>Noting the wiring for the thermostart shown here why don't you remove the start position glow plug wire from the switch and use only the thermostart position for it. You really don't need it to be working while cranking. At least that is my opinion. https://www.hoyetractor.com/is52110-inst.jpg<e>

/e></QUOTE>

This is getting more interesting as we go along!

Following Winston's suggestion, I did disconnect the 2 wires that are connected to ignition switch terminal R2. This disabled the glow plug when starting. After disconnecting this glow plug wire, and with solenoid wire disconnected from solenoid, all voltage readings at all ignition switch terminals were good (12.5v). Sounds good right? Now, when I connected the 12v solenoid wire to the solenoid and took a voltage reading at the switch when turning key to start, the voltage dropped to 11.5v and starter fired intermittently as before. So, when turning key to start with no load due to solenoid, voltage is 12.5v to disconnected solenoid wire. However, when solenoid wire is connected to solenoid, and key is turned to start, voltage drops to 11.5v. Is that voltage drop under load, normal?

When bypassing ignition switch by running wire from battery + to solenoid 12v terminal, it fires every time!

 

[Norm-HT]

"
I think that the battery's current is being consumed by the thermostart glow plug which is always energized at the same time as the solenoid when turning the key to the "start" position. Doing this normal operation does not leave enough current to fully energize the solenoid. In this normal operation if I disconnect the wire to the thermostart plug, that leaves sufficient battery current to fully energize the solenoid/starter."

Is that normal? On my YM2000b the Tstart plug is NOT energized in the start pos., only when I turn key to the TS pos.

 

[markey-HT]

<QUOTE author="Norm"><s>

</s>"
I think that the battery's current is being consumed by the thermostart glow plug which is always energized at the same time as the solenoid when turning the key to the "start" position. Doing this normal operation does not leave enough current to fully energize the solenoid. In this normal operation if I disconnect the wire to the thermostart plug, that leaves sufficient battery current to fully energize the solenoid/starter."

Is that normal? On my YM2000b the Tstart plug is NOT energized in the start pos., only when I turn key to the TS pos.<e>

/e></QUOTE>

Yes Norm. It is normal operation as shown in Hoye's diagram (see terminal R2). The way I found out before seeing the diagram, was when I kept trying to start and the solenoid would just weakly click. When I pulled the solenoid wire to run my voltage checks, I felt the intake around the glow plug was warm. I guess that eases starting in warm weather.

 

[markey-HT]

Forget about the voltage readings, forget about the voltmeter tests!!!!!

Common sense prevails.

When connecting wire directly from +battery to 12v connection at solenoid, it fires every time. Thus, battery and solenoid are good.
When connecting wire directly from +battery to "C" wire at ignition switch (the wire that connects all of the wiring through safetys and on to the wire at solenoid), intermittent starting occurs. Looks like the wiring is the culprit and the ignition switch is fine.

Makes sense?

 

[winston-HT]

Yes.

 

[Norm-HT]

I can't imagine why one would want to activate TS in the start pos. Mine is wired to only activate in Ts pos. Build a fire in intake, then turn to start, (only if needed in cold weather).<LINK_TEXT text="https://www.tracto...wells-vr728-557466-yam240elec-gif</LINK_TEXT>

 

[winston-HT]

<QUOTE author="Norm"><s>

</s>I can't imagine why one would want to activate TS in the start pos. Mine is wired to only activate in Ts pos. Build a fire in intake, then turn to start, (only if needed in cold weather).<LINK_TEXT text="https://www.tracto...wells-vr728-557466-yam240elec-gif</LINK_TEXT><e>

/e></QUOTE>

To keep the fire going while cranking in extreme cold. I would guess more of the older Yanmars were wired that way than not. Just basing that off the several electrical diagrams that I have. Yanmar must have felt it necessary, of course I think humans work there so they could be wrong. <E>:mrgreen:</E>

 

[Desert Dave-HT]

<QUOTE author="Norm"><s>

</s>I can't imagine why one would want to activate TS in the start pos. Mine is wired to only activate in Ts pos. Build a fire in intake, then turn to start, (only if needed in cold weather).<LINK_TEXT text="https://www.tracto...wells-vr728-557466-yam240elec-gif</LINK_TEXT><e>

/e></QUOTE>

Same thing I was thinking from the first post, but figured to let you, Winston and Aaron make the call as you're the experts <E></E>. I'm in the desert, if I ever need the TS I'm moving <E>:wink:</E> .

 

[Norm-HT]

Winston, I seem to recall having this discussion with you many years ago <E></E> I have never used mine in N. Ga.(being a Floridian I only get out when above 60*), but have tested it to see if/how it works. I can certainly see how it could drag down the starting current.

 

[markey-HT]

<QUOTE author="Norm"><s>

</s>I can't imagine why one would want to activate TS in the start pos. Mine is wired to only activate in Ts pos. Build a fire in intake, then turn to start, (only if needed in cold weather).<LINK_TEXT text="https://www.tracto...wells-vr728-557466-yam240elec-gif</LINK_TEXT><e>

/e></QUOTE>


Norm, as an easy test for your tractor, you could disconnect the small 12v wire at the solenoid and turn key to "start" position, and hold it there for about 30 seconds. Release the key and place your fingers on the intake right above the thermostart connection. You may feel that area "warm" as I did. That is how I first found out about the thermostart engaging when in "start" position.

 

[markey-HT]

<QUOTE author="markey"><s>

</s>Forget about the voltage readings, forget about the voltmeter tests!!!!!

Common sense prevails.

When connecting wire directly from +battery to 12v connection at solenoid, it fires every time. Thus, battery and solenoid are good.
When connecting wire directly from +battery to "C" wire at ignition switch (the wire that connects all of the wiring through safetys and on to the wire at solenoid), intermittent starting occurs. Looks like the wiring is the culprit and the ignition switch is fine.

Makes sense?<e>

/e></QUOTE>

I have quoted my previous post. That easy test sealed the deal in diagnosing the problem. That said, looks like I will be installing the starter assist relay as in Deere AM107421. If Hoye has similar part, let me know. Thank you to everyone that contributed to this thread. <E></E>

 

[Norm-HT]

<QUOTE author="markey"><s>

</s><QUOTE author="Norm"><s>

</s>I can't imagine why one would want to activate TS in the start pos. Mine is wired to only activate in Ts pos. Build a fire in intake, then turn to start, (only if needed in cold weather).<LINK_TEXT text="https://www.tracto...wells-vr728-557466-yam240elec-gif</LINK_TEXT><e>

/e></QUOTE>

No, mine is wired just as my schematic shows. (I replaced the switch years ago.) Key to "start" only shorts "C", common, to "B", start, or key to run, c to BR. Must turn to left to activate TS.

 

[Aaron-HT]

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It looks like your schematic is the same as our wiring diagram. Both R1 and R2 go to the glowplug. R2 should be energized when in start position and R1 when in TS position.

 

[Norm-HT]

<QUOTE author="Aaron"><s>

</s><QUOTE><s>

</e></QUOTE>
It looks like your schematic is the same as our wiring diagram. Both R1 and R2 go to the glowplug. R2 should be energized when in start position and R1 when in TS position.<e>

/e></QUOTE>

That could be. My R1 and R2 are not, and were not originally, wired together.

 

[markey-HT]

<QUOTE author="Norm"><s>

</s><QUOTE author="markey"><s>

</s><QUOTE author="Norm"><s>

</s>I can't imagine why one would want to activate TS in the start pos. Mine is wired to only activate in Ts pos. Build a fire in intake, then turn to start, (only if needed in cold weather).<LINK_TEXT text="https://www.tracto...wells-vr728-557466-yam240elec-gif</LINK_TEXT><e>

/e></QUOTE>

No, mine is wired just as my schematic shows. (I replaced the switch years ago.) Key to "start" only shorts "C", common, to "B", start, or key to run, c to BR. Must turn to left to activate TS.<e>

/e></QUOTE>

Norm: since your glow plug operates in TS key position, therefore, you have a wire connected to your R1 ignition switch terminal. Is there a wire connected to your R2 ignition switch terminal??

 

[Norm-HT]

No. There was no wire on R2, so I left it that way. Did not know what it was until later. Operating TS every time you start the tractor is obviously problematic, with undue wear and tear.

 

[markey-HT]

<QUOTE author="Norm"><s>

</s>No. There was no wire on R2, so I left it that way. Did not know what it was until later. Operating TS every time you start the tractor is obviously problematic, with undue wear and tear.<e>

/e></QUOTE>


Norm, I do not know the logic or reason that Yanmar chose to activate the TS when starting the tractor. Maybe they felt that the slightly "warmed air" would aid in warm-weather starting. Or during cold weather starts when using the TS, when turning to "start" would keep the passing air warm. My YM186D was factory-wired this way. In any event, as I previously mentioned, my problem was the wire going from ignition switch "C" through the safetys and wiring, and terminating at the 12v solenoid terminal. Not worth the effort to rip out and replace all safetys and wiring when the relay will easily do the trick and no more worries.

 

[markey-HT]

Just an update. That solenoid relay is working fine. I should have addressed this issue many tears ago. When turning the key, it never misses a beat. Several years ago, I guess I changed out the solenoid for no reason. All alone, it was a problem with resistance in the 12 V wiring due to age. Definetly not worth tracking-down and changing wires when a simple solenoid will do the job. Thanks for all of the insightful replies!!!