No power at dash/ignition

[Jdcolby]

Hello. New to tractors and this thread. I have a yanmar ym1700. Starter went bad in December 2021. The wire from the solenoid to the starter burnt up one day and the tractor ended up shutting down.
Had the starter rebuilt. Installed it and hooked the connectors to the starter backwards. Connected the battery and the engine started turning over, trying to start. The negative cable wouldn’t come off so it tried to start for maybe 20-30 seconds before I could get it off the terminal.
Swapped the wires at the started, reconnected the battery and tried to start the tractor. Nothing. No power at the dash, at all. No headlights. Nothing. 12.8v at battery and at starter. Nothing at the ignition switch. I’m lost. Any ideas? Thank you,
Jon

 

[Roadworthy]

Welcome to TBN. I suspect your tractor is old enough there are minimal (if any) electronics to fry. Start with the easy stuff and check your fuses. If you can score a schematic you might try to determine if you have any fusible links as well. It is possible you have fried your voltage regulator or a diode in the alternator but I'd start with the cheap stuff - fuses.

 

[richriddle]

Here is a wiring diagram for a generic old Yanmar. Assuming the wiring is original, the wire you are looking for is a WHITE wire with a RED stripe (thick ten gauge). The WHITE wire with a RED stripe begins at the starter solenoid and shares the same post as the POSITIVE battery cable.

1. First ensure the WHITE wire with RED stripe is attached to the same lug as the POSITIVE cable from the BATTERY and your starer solenoid. The POSITIVE cable is always HOT; be careful.

2. From the lug on the starter solenoid, the WHITE wire with RED stripe should go to the generator/alternator, so measure the voltage there.

3. After the WHITE wire with RED stripe leaves the generator/alternator, it goes to the VOLTAGE REGULATOR. The voltage regulator on the YM276D is on the left side of the tractor on the metal "firewall" above the starter. It has a plug on it. Measure the voltage there. A voltage regulator cost about $25 many places including here: Yanmar Voltage Regulator

4. From the VOLTAGE REGULATOR, the WHITE WIRE with RED STRIPE feeds your ignition switch and should be HOT at ALL TIMES. Check for voltage there on the "B" connection.

5. The IGNITION SWITCH feeds the Yanmar fuse panel off of the "BR" connection using a WHITE WIRE with BLACK STRIPE. With the IGNITION SWITCH in the "on" position you can meter the WHITE WIRE with the BLACK STRIPE where the wire feeds into the fuse box.

6. Check your FUSES.

 

[rScotty]

Some things don't make sense to me here. In the first place, the owner says that the wire from the solenoid to the starter burned up. That's weird. Some solenoids did have a short stubby wire a few inches long connecting between the solenoid and the starter, so I'm guessing that's the one he means, but it is one very heavy wire. But usually instead of a wire, the connection from solenoid to starter is a bus bar a few inches long. If it is a wire, it had to be the same diameter as a battery cable. That must have been some serious heat. For that wire to burn up, the short circuit had to happen within the starter case itself. I'm surprised there was anything left to rebuild.

BTW, did we find out if his tractor has a generator or alternator? The wiring is is a little different & so are the wire colors. Or someone may have changed it and used different wiring.

Just hooking up the battery backwards for an instant can often be fixed pretty easily with some polarization in old style systems. In those old style generators and voltage regulators needed to be polarized in the running direction. That went for some starters as well.

However, If it is an old style (with generator instead of alternator) and hooked up backwards for more than a fraction of a second then the voltage regulator is probably ruined. Maybe other parts. It's hard to know.

Frankly I would concentrate on getting it running and leave the charging system until later. Polarize the starter field coils properly, including the solenoid. Check the solenoid operation, check the fuses, Label and disconnect the charging system.

Instead of going through every system now, if he simplifies to just an on/off switch to the solenoid plus the starter then he can start and run the tractor. That will make it much easier to troubleshoot the rest and will get it going. A diesel tractor without lights doesn't really need a charging system like a gas engine does. A battery alone will start most tractors dozens of times and can be recharged overnight.
rScotty

 

[rScotty]

Rich, your schematic shows an old style generator wiring system - the kind of generator with a rotor having commutator slots and brushes. But the photo of the voltage regulator is of the style used a generation later. I believe it is the type used with some alternators, not the type originally used with the generator. Note the blue wires.

Yanmar electrics are difficult because they used a wide variety of charging systems including some hybrids of their own. I've seen three different voltage regulators used with their alternators and I'll bet there are others.
rScotty

 

[California]

FWIW here's the back side of the dashboard of a YM240, YM1700's near twin.

(Ignore the rats nest of glass fuses I installed in place of then-unobtainable tiny original fuses).

There's really not much going on, under there.

YM240 (US) and I assume YM1700 (Japan) used the same generator and regulator as 1973 Datsun (non a/c) so replacements are cheap and easy to find.

And for future reference if someone needs it, here's the underside of YM186D dashboard.

https://www.tractorbynet.com/forums/attachments/p1640417ym186drundersidedashboard-jpg.280630/

 

[bmaverick]

Hello. New to tractors and this thread. I have a yanmar ym1700. Starter went bad in December 2021. The wire from the solenoid to the starter burnt up one day and the tractor ended up shutting down.
Had the starter rebuilt. Installed it and hooked the connectors to the starter backwards. Connected the battery and the engine started turning over, trying to start. The negative cable wouldn’t come off so it tried to start for maybe 20-30 seconds before I could get it off the terminal.
Swapped the wires at the started, reconnected the battery and tried to start the tractor. Nothing. No power at the dash, at all. No headlights. Nothing. 12.8v at battery and at starter. Nothing at the ignition switch. I’m lost. Any ideas? Thank you,
Jon

The Parts Manual and electrical schematic can be found here:

Yanmar - Model Cover Pages

YM1700 Originally a Tree Frog. 🤑 A real cheesy production logo. In a rare instance, a YM1700 Tree Frog restored to showroom new condition. This is a beauty. The machine was on a market place, the only image left in the cache to pull from. It would have been great to have more...

www.tractorbynet.com

Just scroll thru the YM1700 2 postings. There are more than 1 manual because it came in Tree Frog and in Red Apple types.

 

[Jdcolby]

Some things don't make sense to me here. In the first place, the owner says that the wire from the solenoid to the starter burned up. That's weird. Some solenoids did have a short stubby wire a few inches long connecting between the solenoid and the starter, so I'm guessing that's the one he means, but it is one very heavy wire. But usually instead of a wire, the connection from solenoid to starter is a bus bar a few inches long. If it is a wire, it had to be the same diameter as a battery cable. That must have been some serious heat. For that wire to burn up, the short circuit had to happen within the starter case itself. I'm surprised there was anything left to rebuild.

BTW, did we find out if his tractor has a generator or alternator? The wiring is is a little different & so are the wire colors. Or someone may have changed it and used different wiring.

Just hooking up the battery backwards for an instant can often be fixed pretty easily with some polarization in old style systems. In those old style generators and voltage regulators needed to be polarized in the running direction. That went for some starters as well.

However, If it is an old style (with generator instead of alternator) and hooked up backwards for more than a fraction of a second then the voltage regulator is probably ruined. Maybe other parts. It's hard to know.

Frankly I would concentrate on getting it running and leave the charging system until later. Polarize the starter field coils properly, including the solenoid. Check the solenoid operation, check the fuses, Label and disconnect the charging system.

Instead of going through every system now, if he simplifies to just an on/off switch to the solenoid plus the starter then he can start and run the tractor. That will make it much easier to troubleshoot the rest and will get it going. A diesel tractor without lights doesn't really need a charging system like a gas engine does. A battery alone will start most tractors dozens of times and can be recharged overnight.
rScotty

this is the rebuilt starter. There is a guy in a town nearby that is amazing at rebuilding auto/tractor electronics.

 

[Jdcolby]

Here is a wiring diagram for a generic old Yanmar. Assuming the wiring is original, the wire you are looking for is a WHITE wire with a RED stripe (thick ten gauge). The WHITE wire with a RED stripe begins at the starter solenoid and shares the same post as the POSITIVE battery cable.

1. First ensure the WHITE wire with RED stripe is attached to the same lug as the POSITIVE cable from the BATTERY and your starer solenoid. The POSITIVE cable is always HOT; be careful.

2. From the lug on the starter solenoid, the WHITE wire with RED stripe should go to the generator/alternator, so measure the voltage there.

3. After the WHITE wire with RED stripe leaves the generator/alternator, it goes to the VOLTAGE REGULATOR. The voltage regulator on the YM276D is on the left side of the tractor on the metal "firewall" above the starter. It has a plug on it. Measure the voltage there. A voltage regulator cost about $25 many places including here: Yanmar Voltage Regulator

4. From the VOLTAGE REGULATOR, the WHITE WIRE with RED STRIPE feeds your ignition switch and should be HOT at ALL TIMES. Check for voltage there on the "B" connection.

5. The IGNITION SWITCH feeds the Yanmar fuse panel off of the "BR" connection using a WHITE WIRE with BLACK STRIPE. With the IGNITION SWITCH in the "on" position you can meter the WHITE WIRE with the BLACK STRIPE where the wire feeds into the fuse box.

6. Check your FUSES.

I believe this is the voltage meter? Not positive, however, the location matched your discription. Looks original to me. I bought the tractor and it had been gone through and fixed up.

 

[Jdcolby]

Again, new to all of this. I assumed this motor has an alternator. Maybe it’s a generator?

 

[California]

I believe this is the voltage meter? Not positive, however, the location matched your discription. Looks original to me. I bought the tractor and it had been gone through and fixed up.

Voltage regulator. Notorious as a trouble point after 40 years. The modern replacement is electronic and potted in plastic (tar?), so waterproof. I think (?) that's the same regulator used on YM240 and 70's Datsun.

 

[rScotty]

this is the rebuilt starter. There is a guy in a town nearby that is amazing at rebuilding auto/tractor electronics.

Is that starter wired correctly? It looks to me as though the hot from the battery is connected to the solenoid terminal that goes to the starter. If so, it would start cranking - but in the correct direction - the moment the battery is connected.
If that fat wire that is connected to the nearest solenoid post is the hot from the battery then the solenoid is being bypassed. What is connected to the other solenoid post?
rScotty

 

[rScotty]

Again, new to all of this. I assumed this motor has an alternator. Maybe it’s a generator?

That's a universal fanbelt driven alternator. In fact it looks like the general type of Datsun alternator that has been already been mentioned. If so, you can just use an automotive alternator and the MATCHING voltage regulator as several have done.

But lets get the starter fixed first.

 

[bmaverick]

I believe this is the voltage meter? Not positive, however, the location matched your discription. Looks original to me. I bought the tractor and it had been gone through and fixed up.

ugh. That is the old school VR for sure. Hoye, Fredricks, ASAP, and the Kumar Bros all sell the solid state replacements.

Even though my machine was a UTDA restore, the VR looked great back then. BUT, a few rodents made a nest for the winter one year and another year a miniature bird made a nest there too. Well, those wires on the VR got a few bites and pecks from the hungry critters. So, I replaced it this year with the solid state.

 

[Jdcolby]

Is that starter wired correctly? It looks to me as though the hot from the battery is connected to the solenoid terminal that goes to the starter. If so, it would start cranking - but in the correct direction - the moment the battery is connected.
If that fat wire that is connected to the nearest solenoid post is the hot from the battery then the solenoid is being bypassed. What is connected to the other solenoid post?
rScotty

View attachment 738007

Yeah, that was hooked up wrong. I left the wires in the position I took them off, when the starter fried.
However that was almost 4 months ago. And just trusted they hadn’t moved. That’s when it got exciting when I hooked the battery up. The wires are switched now.
As for the wire on the other post, I’m not positive. Tracing that today.
Through this process I’m learning to take pictures before I remove anything, so I can put it back correctly.

 

[rScotty]

Yeah, that was hooked up wrong. I left the wires in the position I took them off, when the starter fried.
However that was almost 4 months ago. And just trusted they hadn’t moved. That’s when it got exciting when I hooked the battery up. The wires are switched now.
As for the wire on the other post, I’m not positive. Tracing that today.
Through this process I’m learning to take pictures before I remove anything, so I can put it back correctly.

Excellent pictures and enable us to make wiring comments from the photos alone.

YES, that's a pretty common wiring mistake. I'll bet it was real exciting when you hooked the battery up. My guess looking at the wiring is that it started cranking immediately and didn't even need a key!

Both the large black battery wire and your two white or yellow with a red stripe wires are hooked to the other large terminal. Of the two white with a red stripe...generally one will go to the voltage regulator and then on to the fuse box. The other may go to the fuse box on its way to the ignition switch. The only thing hooked to the nearer large terminal is the two inch heavy wire that goes into the starter itself.

If you had it hooked up like that you did no damage as long as you got the battery unhooked before the starter got too hot. It would be turning the correct direction, but the motor would almost start but may not be able to do so since the pinion gear of the starter could not disengage from the flywheel.

The other wire to the solenoid - the black with the white or yellow stripe - should be the one that is powered by the ignition switch to cause the starter to turn.
rScotty

 

[Williy]

the ignition electronics are usually covered in epoxy
you have no way of finding out what parts being used

willy

 

[Jdcolby]

Excellent pictures and enable us to make wiring comments from the photos alone.

YES, that's a pretty common wiring mistake. I'll bet it was real exciting when you hooked the battery up. My guess looking at the wiring is that it started cranking immediately and didn't even need a key!

Both the large black battery wire and your two white or yellow with a red stripe wires are hooked to the other large terminal. Of the two white with a red stripe...generally one will go to the voltage regulator and then on to the fuse box. The other may go to the fuse box on its way to the ignition switch. The only thing hooked to the nearer large terminal is the two inch heavy wire that goes into the starter itself.

If you had it hooked up like that you did no damage as long as you got the battery unhooked before the starter got too hot. It would be turning the correct direction, but the motor would almost start but may not be able to do so since the pinion gear of the starter could not disengage from the flywheel.

The other wire to the solenoid - the black with the white or yellow stripe - should be the one that is powered by the ignition switch to cause the starter to turn.
rScotty

Getting both wires correctly hooked to the correct post was the trick. Thank you for taking the time to respond to this thread. Very much appreciated.
Side note, it still wouldn’t start after I got it hooked up correctly, but I had power everywhere I should.
I cleaned the fuel filter and in the process I had let air into the fuel system. Once I bled the air out the tractor fired right up.
Thank you again.

 

[rScotty]

Getting both wires correctly hooked to the correct post was the trick. Thank you for taking the time to respond to this thread. Very much appreciated.
Side note, it still wouldn’t start after I got it hooked up correctly, but I had power everywhere I should.
I cleaned the fuel filter and in the process I had let air into the fuel system. Once I bled the air out the tractor fired right up.
Thank you again.

I'm glad to hear it started right up. You are very welcome to the help & thanks for the update.
rScotty

 

[Williy]

Great! another tractor back on its feet
Its always good to hear someone got
their tractor back in operation

willy