1641 Fuse Blown, won't run, not ignition switch.
 

So I was installing my mower deck, brake pedal was in the lock position and the tractor was running. I was moving the hydrostatic up and down and then the tractor shut off. I found that I blew the fuse that goes from ignition switch to the starter solenoid. The last time I had an issue with this my headlight was lying on the exhaust shield, the tractor would run but when I would move the key back to lights it would blow the fuse. This is not what is happening now, the tractor will start for a few seconds, the fuse will be blown and the black side of the wire going to the ignition switch will be very hot.
I cannot find any wire that is grounding out anywhere, I tested the ignition switch and thought it was bad but the new switch is doing the same thing.
I left the key and run without a fuse and used my power probe to engage the solenoid which started the tractor but it would die after about 5 seconds.
I'm hoping someone has an idea of what is going on.

Do you have a schematic for your 1641?

It looks like the fuse is bypassed in the "start" position so that explains why it blows soon after you are in the "run" position. Yep, you have a short somewhere.

Obviously you have a short. Time to dig out the DVM and measure between Chassis Ground and the Ignition Switch "R" terminal (Red/White) wire, engine off. There should NO resistance. If there is, you will have to trace down what is on that circuit causing your issue.

Thats great but how exactly would I complete this task, youtube tutorial?

Thanks

Do you own or have access to a digital multi-meter, an analog multi-meter, or a voltage test light??

Check the tail light connectors as one may be loose, worn and grounding on the frame BTDT

I have all of those and a power probe, have the tools, just not much knowledge when it comes to electronics.

So I'm having a really hard time, if I unplug the ignition switch and I run a jumper from the S terminal straight to the battery the tractor will start and run but for only about 5 seconds and then dies. If I run a jumper from R to battery, the starter actually moves a little bit, is that telling me there's a short between s&r somewhere in the mess of wires?

If you look at the bottom of the bowl of your carburetor, you will see a plug with two wires attached to a thing called a fuel solenoid. The fuel solenoid's purpose is to stop fuel from flowing through the main jet of the carb when you shut the key off. The idea being, to prevent backfires caused by raw fuel being sucked thru a non running engine and exploding in a hot muffler.
In normal operation, when you turn your key to the start and/or run position, 12 volts is delivered to the fuel solenoid and it stays open allowing normal fuel flow until you turn the key to off.
When you have the key switch unplugged, there is no 12 volts applied to the fuel solenoid. Therefore when you jump the starter solenoid, the engine fires and dies because the fuel solenoid has remained closed and the engine is not getting enough gas.

Not clear on what you mean by starter "moves a little bit" , but if you are cleanly applying 12 volts only to the "R" terminal of the plug, no the starter should not move.

Yes so if I apply 12 volts to the R terminal, the starter tries to spin and the wire grounds out onto the battery terminal.

I think there is a wire that runs from the starter solenoid to the fuel solenoid that opens the fuel solenoid in the start cycle. I believe there is a diode in that wire to keep power from feeding back through the wire in "Run". If that diode failed would the starter solenoid be activated in 'Run"?
Cannon

That is correct. A diode is a current flow directional device. The diode (circled in red) allows current to flow from the starter's battery cable lug thru the fuel solenoid when the starter solenoid is activated (key in "start" position). Then when the key is released to the "run" position, the diode prevents current from flowing back towards the starter motor.
Usually when diodes fail, it is because they burn out (go open). In this case the diode would appear to be shorted.

To verify this, the diode lead will have to be removed from the starter, then apply 12 volts to the "R" terminal of the key plug. Use a test light, connect the alligator clip to battery ground and probe the lead removed from the starter. If it lights, you have a shorted diode.

Okay so I disconnected the battery, energized the R terminal with a test light on the diode wire removed from the starter and it lights up.

The black barrel hickey a couple inches up from your test light probe is the diode.
So now reverse your polarities. (i.e. apply the 12 volts to the ring terminal and put the test light probe into the key plug "R". If it still lights, your diode is shorted.
You can buy the assembly, Google "959-3689 diode assembly" for about 20 bucks
https://www.google.com/search?q=959-...t=gws-wiz-serp

or

you can buy a diode for a couple bucks and replace it yourself. I understand a 1N5400 diode is a good replacement.
https://www.ebay.com/sch/i.html?_fro...A&_dcat=260820

If you replace it yourself, pay attention to the line at one end of the diode. That determines polarity and you must put it in the same way as the old one.
(i.e. end with line towards the carb.)

Okay, I'm going to have to go back out tomorrow, because I already put my toys away LOL.

So I put the test light on our and lit up the diode and the test light lights up, so it lights up doing it both ways.

There are specialty diodes that could give this indication, but in your case, no specialty, so you have zeroed your problem down to one thing.
Now you can consider how you want to fix it.

Just want to say that your diagnostics and directions are spot on in this thread. Nice work, and great job explaining it.

Thank you.

So I ended up ordering the diode assembly and a new fuse holder, so hopefully this will do it, we will see. Thank you in advance for the time you've taken to help me.

Just FYI, not all Vanguards have the fuel shut off solenoid. You can simply remove it and replace it with the factory plug or do as I do on all my Vanguards, remove the solenoid, cut the plunger off and then re-install it. If it's not on the engine it can't cause problems.:beerchug:

Yes I ordered the diode, and the place sat on it for 3 days, so I called them and they said that it's discontinued and I could not get it. Not sure when they're going to tell me that.

Cut the plunger of the solenoid and be happy

That's why it's hard to beat Amazon.

https://www.amazon.com/HUABAN-1N5391.../dp/B08MDYRLWD

I think the 1.5 amp will work or if you want bigger these are a 5 amp.
https://www.amazon.com/20-Pieces-SR5...NsaWNrPXRydWU=

If anyone is curious,
I did some bench testing on a briggs carb solenoid.
At 12.5 volts it draws 350 milli-amps (a little over 1/3 amp)

So of course I ended up finding one on Amazon LOL. I ran out to the garage, clip the ends off the old diode, j-hooked the diode and remaining ends so I had a good bond with the solder and retention. Threw some sleeving over it, went out to hook it up and of course the fuse immediately blew.
Then I put a larger amp fuse in it this time, 30 amp and the tractor actually ran for about a minute until it blew.

How do I get the solenoid out of the carburetor?

I must still have a short somewhere, this is getting ridiculous LOL. Could the solenoid itself be grounding out?

Today is not the day to be working on this, since it is outside and of course it's raining today.

So since that diode goes directly to the starter, I'm assuming that once the tractor starts if it was just a wire without a diode it would actually ground out correct? Because I noticed that when I check polarity on the main coming off the solenoid to the starter it shows negative and then changes the positive once the solenoid is activated.

Can't tell from your pictures but the lead on the end of the diode with the silver band around it should go towards the carb.
If that is not the case, the fuse will blow.

Solenoid is on the rear bottom right side of the carb. You should be able to get to it from the top by removing the air cleaner assembly including the base plate. Close the choke to prevent dropping a screw down the carb.

Silver end is opposite the starter

I don't think your short is in the carb solenoid because I don't think the tractor would run if it is shorted or failed. You need to use a multi-meter like Ironman posted. Set the meter to Ohms(resistance) and attach one lead to the black wire leaving the fuse holder and the other to ground. Try that and report back.

A question that should have been asked from the get-go, and that is...
What is the part number of the new ignition switch that you installed??
Just asking because many ignition switches look alike on the outside but make different connections inside when you turn the key.
Don't want to chase the wrong tail here.

Second question....
What is the number on the new diode you installed?? (something like 1Nxxx)

So the ignition switch HDK-152 and diode is 1N5400. I can get the tractor to run now but only if the red wire to the voltage regulator is not attached. Once I plug that wire in, the fuse blows.

925-3163 is the correct switch, not sure what a hdk 152, is it a cross to the cub cadet one?.

HD Switch Ignition Key Switch for Cub Cadet MTD White Outdoor 925-3163 725-3163 925-3163A 725-3163A 725-3163P - Dual Dust Protection System - w/ 2 Keys & Free Carabiner https://a.co/d/gH1cFUd

Your problem started with the deck lift, the main wire harness runs along the frame on the left side and runs up through the steering column area where there is a junction connection. Check that area for a wire that has rubbed up against the frame or the steering wheel shaft.

That was the first thing I did, could not find any rubs or pinches.

I'm not entirely familiar with the specific wiring on this CC but to me red means hot and black means ground so when I see a red wire plugged into a black wire it makes me wonder if that's the way it's supposed to be?

That wire goes to the carburetor solenoid, black sleeving maybe..

It's entirely possible that you have a bad voltage regulator. I don't like the B&S regulators, I replace them with Kohler VR's. This is the Kohler part # that I use 41-403-10-S regulator.