YM1100D electrical issue

   / YM1100D electrical issue #1  

kwms56

New member
Joined
Oct 11, 2025
Messages
1
Tractor
Yanmar YM1100D
I've owned this tractor for about 30 years, and ever since acquiring it the charging system (really the whole electrical system) has been a complete wreck. Have always just kept the battery charged up with trickle charger. That's now changed; recently I did a lot of work on the tractor and basically redid EVERYTHING electrical. Good news is that everything now works, and I added some accessory items: light bar mounted on ROP frame, digital volt gauge, accessory "cigarette type" plug.

Here's the problem: I'm getting between 16 and 17 volts produced by the generator going through the voltage regulator/limiter. Way too much. This machine has a 3-wire regulator with yellow, red and black. Black goes to ground. Yellow ties into yellow wire coming from the gen. Red connects to ignition switch and gets power when switch is in "on" position. I have notebooks full of manuals that came with the tractor, and I've followed the wiring schematic carefully. The regulator is new, and supposedly it's the correct one for the tractor.

Any ideas would be appreciated.
 
   / YM1100D electrical issue #2  
Pretty sure your dynamo puts out ac voltage and your rectifier/regulator converts it to dc voltage. Are you aware of that? It should put out 15 to 20 something ac volts depending of speed.
 
   / YM1100D electrical issue #3  
@kwms56 Welcome to TBN, and congratulations on getting the rewiring done and improved.

My bet is that @winston1 is right, you are measuring AC, and the system is ok. How is the voltage after the regulator?

All the best,


Peter
 
   / YM1100D electrical issue #4  
Should be a Factory Dyno., With all the added lights and Gauges. I would change to a Alternator. I've seen several times that people used a GM style Alternator with a built in Regulator. Then you can Run it straight to the battery and then leave all the Wiring to the Tractor intact! Your Charge/Alt trouble light won't work correctly or at all or that matter. Just add gauge to it.
1760189406617.png
 
   / YM1100D electrical issue #5  
I agree with Winston. It sounds almost like ou are measuring AC voltage from a decent dynamo right at the dyno outputs - and it sounds like that AC voltage is about right. In fact, AC output from the dyno at working RPM could be a little.higher and still be OK.

What matters most is the DC voltage delivered to the battery.

Try this: Measure the DC voltage across the battery terminals before you start the motor some day and then again across the battery terminals with the motor running.

The first measurement after the tractor has set overnight should be somewhere around 12.1 to 12.8 volts depending on the health of the battery....and the second measurement with the engine running at normal working RPM is generally somewhere in the range of 13 to 15 volts DC - though I've seen them higher than that & the only downside is a shorter life for the lights.

The charging voltage always has to be a little higher than the battery voltage for charging to take place.

rScotty
 

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