# How bypass safety switches?



## gman51 (Mar 22, 2016)

I bought a Husqvarna yth20k46 riding mower. The mower would start and run just fine but the deck mounting bracket was broken out of the deck. I had the mower deck bracket welded back on. So I reinstalled the deck and was going to try mowing with it.
I started the engine and drove it to where I was going to mow. I engaged the mower deck belt and I noticed the belt pulley was barely moving if at all. About that time the engine quit. I thought what heck is the reason for the engine quitting let alone why the blades were barely moving if at all. Mind you all the other times I ran the engine and drove it I never had the belt lever in the engaged position.
I started checking and I had no power to the engine or anything electrical except I had power at the starter solenoid. That figures because the battery cables run directly to the solenoid. Turn the key and no lights or even a click at starter. I found the main fuse and it checked okay not blown.
Further checking when I pushed in the clutch pedal the engine would start but it would quit when I left off of the pedal. I later figured the blade lever safety switch had failed and was probably causing the engine to quit.
I have decided to bypass the clutch and blade safety switches. They are 4 prong plug so I don't know which of the five wires going into the plug need to be cut or tied together. I read somewhere that just cutting all the wires into the plug will bypass the plug. Another said the two inside terminals are connected and can remove the connecting metal or put a toothpick in those two plug terminals. I don't see a metal piece connecting the two inside terminals.
BTW......I trashed the clutch safety switch trying to remove it from the frame. So now I have to bypass that switch. I still have the blade and seat switch to bypass. I wish I had known it was probably the blade safety switch that was bad because then I wouldn't have ruined the clutch switch. Oh well shoulda, coulda, woulda don't mean squat now. It is bypass time now.
I read that factory started using 4 prong plug to keep people from just unplugging to bypass the two wire switches. Supposedly tying the two inner contacts on the 4 prong plug together stopped the bypass by just unplugging it because the two would cause a dead short if unplugged. Supposedly cutting all the wires will bypass the switch.
Anyone care to add their two cents? No need to tell my I shouldn't bypass the safety switches because I am going to do it. I just want to know if cutting all the wires at plug will bypass the killing of electrical power to engine. Every mower I have owned had the safety switches bypassed because they failed.


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## thepumpguysc (Jan 25, 2015)

U could un-plug the connector to get what u need bypassed & "paper-clip" the others..
Just straighten out a paperclip & wiggle it in the connector to join what u need to join.


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## gman51 (Mar 22, 2016)

I believe I have it figured out and will try it tomorrow.
The four prong switch the two prongs on right side top and bottom are one circuit for when whatever is not in use. Those two make a closed circuit when not in use but when the plunger goes in when the item is being used those two contacts circuit is opened and the other two terminals that were open circuit are now closed circuit. The plunger changes which two terminals are now open circuit and which two are closed. Using an ohm meter you can see which side of terminals are open and which two are closed.
If I am right then the wires going to the two terminals that are closed circuit when plunger is out{not in use} need to be taped together. The other open circuit terminals just leave those wires going into the plug. Just leave the plug disconnected from the switch with the other wires taped together to make circuit.

Am I correct thinking this will bypass the safety switch?


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## gman51 (Mar 22, 2016)

Well that didn't work for nothing.
I have a strong battery that does have a good ground to tractor frame. I have power at the starter solenoid battery post but no power at wire from ignition switch to solenoid when switch is in the start position. The main fuse has power and the fuse is good. I am not getting any power to the ignition switch for some reason. 
I checked all ground connections seem good. I am totally at a loss what the heck is causing no power to the switch. I even checked the switch and it is functioning as it should in all positions. Without power to switch I have nothing getting power.
I have a really large boat anchor here on wheels.


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## FredM (Nov 18, 2015)

have you checked the positive feeder wire from the battery pole on the solenoid to the switch, if this is open circuit, you wont get power to the switch.
have you thought of trying to google a wiring schematic for this rider, it might help you a lot, those multi wire safety switches do two things, when the clutch/brake pedal is locked on and same with the deck being isolated this then makes a circuit for the start circuit to the solenoid from the start switch, the seat sensor switches straight to earth to kill the coil if you are not sitting in the seat, if the seat switch is multi wire then it will have the same function as the brake and deck control, the engine should crank but not fire up if not sitting in the seat, when you release the clutch/brake pedal and the deck control, this then shifts the internal switches to the kill position should you lift your bum off of the seat.

Seeing you are hell bent of removing the safety switches, you would need to rewire the start and run system in simple mode, the kill wire that comes from the coil (black most times) could go straight to a push button or toggle switch straight to earth and the rest is quite easy, but that is as far as I will go, as much as I dislike the sensors, they were put on for a reason, mainly the inexperienced and kids.


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## gman51 (Mar 22, 2016)

well it's running. hoo ray!
I was doing more checking with the multi meter and now I found the fuse was blown. Evidently when I was crossing the safety plug terminals it blew the fuse.
So I removed all jumps and did just crossing the clutch pedal safety plug left side contacts. I had the blade safety switch out and connected the plug to it. I cut the seat safety plug wires off the plug per reports that will end the seat safety.
For some unknown reason I pushed in the blade safety plunger and turned the key. Well the engine started and ran. In order to start the switch plunger needed to be pushed in and once it is running then can let go of the switch plunger. I started mowing with it and I had to back up but that would make the engine quit. Evidently the back up safety switch kills the engine if blades are engaged. I thought well try pushing in the plunger again and sure enough with plunger in the mower can go in reverse without killing th engine. I guess I will reinstall the switch to be operated by the blade engagement lever.
I am suspecting the first failure cause could have been the seat or the clutch safety switch. Both of those are taken out of the circuit now.
So this mower cost me total of $175. Let's not add in the mental frustration to get it running. It looks like new and it does a good job mowing. I am guessing a new one from Lowe's probably cost around $900-$1200 so I am a happy camper with it.
......
The JD that I got for free is now running. Total cost to get it running was less than $20. The battery that was supposedly bad is good after an over night 2 amp. charge. It doesn't have a mower deck and I am not sure if I will get one for it. I might sell it for someone to use on a deer lease or just a run about over a lot of property.
So that's two out of the three are now running.


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