YM186D starting/voltage problem

[old grayfellow]

My 186D has for some years had this thing where when I turn the key sometimes I'll just hear the solenoid click but the starter doesn't engage, but if I try the key again 1-3 times it would always eventually engage the starter and the engine would start. Kind of an annoyance but it would always start after a few tries so I didn't track down the problem. A couple years ago I had the feeling it might've been dirty contacts or something in the ignition switch so I took that off and cleaned it all up, no change.

But since yesterday, it has gone to a new level of problem; basically the solenoid doesn't even click, just nothing. I cleaned the battery terminals thoroughly and greased them, and tightened well, but no improvement. Battery voltage is 12.7.

So first I tested voltage at the "trigger wire" on the solenoid. I expected ~12V when key is turned to "start", but it only showed around 3.6V. If I held the key in the start position, voltage would climb gradually over 10 seconds or so, but would only reach about 5.1 volts. So if i'm assuming correctly that the solenoid wire should be supplying 12V looks like this might be the issue (insufficient voltage to trigger the solenoid).

But from this point I'm not clear on why there would be this low voltage. I have some info from a service manual on testing the solenoid, but looks to me like the problem might be upstream of the solenoid.

Found an electrical diagram here: yanmar ym186D \\ circuit diagram
and from what I can see it looks like there should be nothing between (12V) power from the ignition switch and the solenoid except the "safety switch" (which has long been defeated/bridged on my tractor).

So I'm left thinking that it must be a dirty connection somewhere between the ignition switch and the solenoid, though it seems odd that there would be a much reduced voltage (3.6-5V) but consistent.

Am I missing something? Any suggestions?

 

[careyo63]

The connections are clean and good. Take the Alternator and Reg to a Auto parts that can check it.
Causes of Inconsistent Voltage:

• Faulty Voltage Regulator: If the voltage regulator malfunctions, it may fail to maintain a consistent output voltage. This inconsistency can result in issues like dimming lights or other performance problems2.
• Environmental Factors: Changes in supply source or environmental conditions can affect the input voltage, leading to fluctuations in the regulated output voltage

 

[ponytug]

Many key switches have internal contacts that gum up and / or corrode with time. The low voltage that climbs slow suggests a poor contact some where between the solenoid and the battery. I would trace it with a voltmeter, but my personal bet would be a switch that needs cleaning or replacing.

To clean the switch, I would disconnect the battery, and then shoot compressed air in the key slot, followed by contact cleaner, and then while it is wet with contact cleaner work the switch ten or twenty times, then add more contact cleaner and repeat, then get it wet with contact cleaner and blow it out, but watch out for the spray (eye protection!). I usually finish with a good spray/soaking of DeOx-It, and moving the switch twenty or thirty times. Then connect the battery, and try it.

(If you haven't tried it, I think that DeOx-It is a really impressive product for cleaning contacts. I prefer the spray.)

None of the tractor switches that I know of are really totally sealed, so dust and gunk does get in.

All the best,

Peter

 

[careyo63]

My Org. Ym2000 use to stick in the Start position. I used Wd. 40 and sprayed the key itself and inserted it. It moves much better but to the day I move the key back to the Run position. If I don't move it back it's super slow in doing so. Does it to the day! Knowing this I turn it back from the start to run from the habit of doing so. I have noticed the Voltage trouble light will flash if I don't. No cover on the Ing. switch and water getting into it was my guess. The Org. key has damage to it and is actually bent a little. If I use a new key undamaged I doubt I would have trouble with it.

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[old grayfellow]

Many key switches have internal contacts that gum up and / or corrode with time. The low voltage that climbs slow suggests a poor contact some where between the solenoid and the battery. I would trace it with a voltmeter, but my personal bet would be a switch that needs cleaning or replacing.

To clean the switch, I would disconnect the battery, and then shoot compressed air in the key slot, followed by contact cleaner, and then while it is wet with contact cleaner work the switch ten or twenty times, then add more contact cleaner and repeat, then get it wet with contact cleaner and blow it out, but watch out for the spray (eye protection!). I usually finish with a good spray/soaking of DeOx-It, and moving the switch twenty or thirty times. Then connect the battery, and try it.

(If you haven't tried it, I think that DeOx-It is a really impressive product for cleaning contacts. I prefer the spray.)

None of the tractor switches that I know of are really totally sealed, so dust and gunk does get in.

All the best,

Peter

Dirty internal contacts seems very plausible.
I just cleaned all the external terminals and each wire ring connector with steel wool till they're bright metal. Put wires back on, and here's what I got (photo--

voltages shown in red)
3-4V makes no sense, unless something inside is not making good contact or something to that effect..
I'll hunt up some contact cleaner/deox-it and give it a try.
Thanks

 

[old grayfellow]

Dirty internal contacts seems very plausible.
I just cleaned all the external terminals and each wire ring connector with steel wool till they're bright metal. Put wires back on, and here's what I got (photo--View attachment 864477voltages shown in red)
3-4V makes no sense, unless something inside is not making good contact or something to that effect..
I'll hunt up some contact cleaner/deox-it and give it a try.
Thanks

Actually I was also thinking to take apart the ignition switch body and clean it out, but I can't see any screws or other fasteners. Maybe the metal part of the body (with the lock tumblers etc) is threaded onto the plastic part (with the electrical connections)?
Anybody know how to disassemble one of these switches? (If it can be done at all)

 

[ponytug]

Actually I was also thinking to take apart the ignition switch body and clean it out, but I can't see any screws or other fasteners. Maybe the metal part of the body (with the lock tumblers etc) is threaded onto the plastic part (with the electrical connections)?
Anybody know how to disassemble one of these switches? (If it can be done at all)

These switches aren't really designed for disassembly, at least in the ones that I have handled.

3V is very suggestive, to me of a corroded wire or a worn or gummed switch.

I would also double check both the battery terminals, and both ends of both the positive and the negative cables. All are great places for a little corrosion, or loose fittings to have a lot of resistance. I would check the 12V+ wire to the switch before you do too much more. Does it get 12V at the switch? Does it get 10-12v if you put a load on it (like a headlight)? Sometimes wires fray and corrode at the wire to connector junction, (that is under the crimp plastic), and the damage can be hard to see. I had a flakey starter issue that turned out to be fraying, and then arcing, inside the crimp on eye for the wire to solenoid. It was only after more than a little time chasing other possibilities that it registered that the little connector was "too floppy", and when I cut it open it only had a couple of intact copper strands left.

 

[bmaverick]

Many key switches have internal contacts that gum up and / or corrode with time. The low voltage that climbs slow suggests a poor contact some where between the solenoid and the battery. I would trace it with a voltmeter, but my personal bet would be a switch that needs cleaning or replacing.

To clean the switch, I would disconnect the battery, and then shoot compressed air in the key slot, followed by contact cleaner, and then while it is wet with contact cleaner work the switch ten or twenty times, then add more contact cleaner and repeat, then get it wet with contact cleaner and blow it out, but watch out for the spray (eye protection!). I usually finish with a good spray/soaking of DeOx-It, and moving the switch twenty or thirty times. Then connect the battery, and try it.

(If you haven't tried it, I think that DeOx-It is a really impressive product for cleaning contacts. I prefer the spray.)

None of the tractor switches that I know of are really totally sealed, so dust and gunk does get in.

All the best,

Peter

Peter, I've had good success with CRC's QD Electronics spray cleaner too.

This is the headlamp switch I repaired.

 

[careyo63]

Mine works great noticed that This Eve, WD-40 on the Key works!

 

[ponytug]

Peter, I've had good success with CRC's QD Electronics spray cleaner too.



View attachment 864557


This is the headlamp switch I repaired.

It is a great cleaner, and one of my favorite contact cleaners, too! I think where DeOx-It really shines is restoring the electrical conductivity of corroded and oxidized / weathered contacts. I think it both cleans and improves conductivity.

Now that I think about it, of the fluids / spot lubricants that have around the shop, many of my favorites are the CRC products. I use their non-chlorinated brake cleaner (basically high pressure acetone) for getting all sorts of used items cleaned up for service again.

All the best,

Peter