mower started to crank, and then everything died

cvorking

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I have a Toro Wheel Horse 520Xi (1998 vintage). I tried to start it last night. It cranked over a couple of revolutions and started to run when everything died - instantaneous shutdown - no lights, nothing. The battery is new and voltage checks good. I checked the fuses, all 4 are good. I pulled the ignition switch, cleaned the terminals and checked operation with an ohm meter... all good. I checked the hot wire from the starter to the ignition switch, and it is OK. I checked the ground to the motor, OK. There are 3 relay's. I pulled them, cleaned the contacts and sprayed contact cleaner into the base. I tried switching them around... still nothing. Other than a satanic exorcism, I'm stumped. I'm out of work and really can't afford to take it in to be checked out. Any enlightenment would be greatly appreciated.
 

Rivets

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You can get a service manual at this site, which may be of help. https://www.toro.com/en/parts/partdetails?id=25537. Has electrical troubleshooting and demystification guides. These problems take a good meter or trouble light, plus patience to solve.
 

cvorking

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I have downloaded the manuals, and they pointed me in the normal directions, but after checking all these out, I'm still not able to find the problem. What is so puzzling is that the fuses are OK, but that is exactly what it acts like... the main fuse blown. If the lights would come on when the key was turned one position... that would confirm power is flowing thru the circuits. When I pulled the ignition switch, I kept one probe of the multimeter on the "B" pole and checked all the other poles while turning the key. They all beeped like they should, and there was no beep when switched off.
 

Rivets

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Page 14-4 of the demystification guide is where I would start. With the key in the start position check for voltage at the starter solenoid. I’m guessing no voltage so you are going to have to follow the wiring diagram back to the key switch to find out where you are loosing voltage. You need to check both sides of the each component. Make sure the brake is on, PTO off and unit in neutral. An assistant will be very helpful and patience is the key. I always tell my students when doing electrical troubleshooting, NEVER ASSUME ANYTHING, CHECK EVERYTHING TWICE.
 

cvorking

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Thanks. I'll give it a shot. I pulled the connecting plug from the back of the ignition switch, took a paper clip and jumped from the power wire to the headlight wire... nothing. There is voltage on the wire going into the switch. Trying to check for everything, I pulled the fuse box loose, pulled the fuses, sprayed contact cleaner, put the fuses back and checked the connectors on the back side to make sure current was passing thru. It was. I've looked at the wiring diagram for any hidden inline fuses, and I only see the 4 in the fuse box.

Is there any way I can check the relay's? There are 3 of them on this model. Another thing I just looked at, there IS an electronics module (P/N 94-7612). I don't know if there is any way to check that... not real sure where it is located.
 

Rivets

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Because I work in a repair shop I have good relays around, so I just swap out all three relays and then put back one relay at a time to find the bad one. I know you can’t do this so you can GOOGLE “how to check lawn tractor relays” and find videos on how to check them. Did you look at the service manual and the demystification guide on the web site I posted?
 

bertsmobile1

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If you look at the wiring manual you have been directed towards you will see an interlock module.
It is situated on the floor of the mower behind the dash.
If you read the circuit diagram you will be able to see it is fairly easy to bypass if you make some jumper wires with the correct terminals on the ends.
Use this to check if the module is working properly.
Also note that some of the manditory safety circuits will also be defeated by doing this so it should be only used to test the module.

If you can not work out how to bypass it then remove it and take it to a Toro dealer for checking.
I will not give instructions on an open forum how to do this .
If you can not unerstand how the circuits work then you should not be bypassing them, for your own safety.
The modules are easy to repair usually one of the diodes goes open circuit and the internal wiring of it is shown in the manual you have been directed to.

Unfortunately Toro's legal team forced them to fit such a device because Creationist Judges believe because we are all created in the image of a deity no person can be too stupid for their own good.
Thus if anything can be modified or simply removed and if the doing of this allowed the idiot moron to manage to injure themselves it is Toro's fault because if we are too stupid for our own good then the deity we are images of must also be too stupid for his ( always a he ) own good.
 

shania50

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this may sound stupid but ad extra ground, run from battery to frame or engine, some times the wiring will get where it does not work so well
 

cvorking

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I think it is time for a long draw on a mason jar. I checked the voltage (again) by grounding out on the motor where the negitive battery cable attaches and touching the positive cable at the starter solenoid, 12.6, at the master fuse (both sides) 12.6, at the ignition switch, 12.6. I turned the ignition switch to the first position (run with lights)… no voltage at the switch... no voltage at the fuse box after the fuse, but I still have 12.6 on the other side (lead from starter solenoid). The fuse is still good.

I looked at some of the video's on testing relays, some used power to some of the terminals, some did not. I guess I'll flip a coin and try one.
 
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