Snapper Pro S200XT Wiring Schematic Explanation

[rajthepilot]

In a forum 2 days, I requested some help regarding my mower's wiring. 'StarTech' was kind to help me with the diagram. I then spent hours looking at it and following my mower's wiring to make sense of it all and then I wrote down what I learn, to help diagnose it now and also in the future. I'm posting what I learned here, so hopefully it helps some one else as well. I'm posting in multiple messages as it's very long. I do have one question about the wiring diagram that I couldn't figure out. When the ignition is off, G & M & A at the ignition switch are connected. But what purpose does it serve to connect the A?



Now I will describe my understanding of the Wiring Schematic Diagram of Snapper Pro S200XT Zero Turn Mower with a Briggs & Stratton Engine

The 'Time Delay Module Schematic' shown in the upper section of the diagram. Top left is 2, Bottom Left is 1, Bottom Right is 3, Middle Right is 4, Top Right is 5. Ports 2 and 5 always have continuity, unless 12 volts DC are given to Ports 1 and 3, then Ports 2 and 4 are immediately connected. If current stops, there is about a 1 to 2 second lag before connection shifts from Ports 2 to 4 TO Ports 2 to 5.

Time delay module - seat delay - ignition delay - I think are all the same thing (please correct me if I’m wrong)

The time delay module is below the seat switch and towards the right side of the mower on the Snapper Pro S200XT

The 'Starter Relay' is below the seat switch on the Snapper Pro S200XT and towards the left side of the mower. - If current passes between Blue 86 and Green 85, then it makes a connection between Yellow 30 and Yellow 87, otherwise the yellow wires have an open circuit

Both Starter Relay and Time Delay Module are hard to reach in the Snapper Pro S200XT, but then again so is most of the wiring, including the solenoid, the oil filter. Everything is in tight spaces.

Ignition Switch has 7 wires coming out of it, but 6 connections, M, L, S, B, A & G (2 of L are connected to same prong / port). As the diagram shows on top left. If key is in 'Off' Position, G & M & A are connected. If key in 'Run' position, then B & L & A are connected and if key in 'Start' position, then B & L &S are connected.

M is for Magneto (White Wire). If Magneto is connected to Ground, it causes a short circuit and stops it from working, it won't send electricity to spark plug to produce sparks. S is Starting, B is from Battery, G is Ground, L ports have 2 wires coming out, one of them powers the Fuel Solenoid (also known as anti back fire valve, located at the base of the carburetor – I got this form a youtube video -

). When 12VDC (volts direct current) is applied, that allows the flow of fuel to the main jet of the carburetor). The other wire from L goes through a series of safety switches to power the Starting Relay, and A powers the PTO

Based on the wiring diagram, if you're in the "Run" key position, you should hear a click if engaging the PTO (the engine doesn't need to be running)

If PTO button is engaged / pulled up, "S" wire won't get power to the starting solenoid to start the engine.

When key is off, M & G & A are connected. (I’m not sure why A is connected)

Magneto (aka ignition coil). If connected to negative battery terminal, it'll stop it from working.

The Top of the Diagram shows 'LH Neutral Switch' and 'RH Neutral Switch". These switches are on the left and right side of the Ground Speed Levers. When you push them outwards, the levers push those switches and close the circuit. When you pull them in to drive, the circuits become open.

PTO switch has 8 prongs. One side has 3, middle has 3, one side has 2. When PTO is disengaged, "pushed in", then the outer sides (3 prongs and 2 prongs) are connected. When it is engaged (pulled up), the 3 outer prongs are connected with 3 inner prongs.

When testing, you're testing "flat" to "flat" meaning the prongs that are parallel to each other, not side by side. So if you see prongs like this "=" these are parallel, and if you see this "- -" these are not. You would test "=" (top and bottom) and not "- -" (side by side) with each other for continuity using multimeter. Some switches just have "=" and some have "= =". When you have 4 prongs, it means two will have continuity when not pressed and two will have it when pressed. If you have "=" (I'm trying to mimic the shape of the prongs), then they'll have continuity when the button is pressed. Press it slowly, so you can check if it has any dead spots. If you have 4 parallel, then you test outer and inner.

Parking Switch - The position in the diagram shows when the parking switch is disengaged, lever down. You also have to rotate it 180 degrees, and that's how I see it when I pick up the seat on the Snapper Pro S200XT. The orange/green wires are on the top.

So if the parking switch is engaged (lever up), Orange from the PTO connects to Orange/Green and Blue disconnects from Orange / Green. When parking is disengaged (lever down), Blue connects to Orange / Green and Orange disconnects from Orange / Green

Seat Switch: The diagram shows Normally Closed, NC, and it is closed if you're sitting on the seat and the button is depressed. Then the two orange / green wires on the left are connected to the two violet wires on the right in the diagram. The violet wires are connected with each other, so current can go freely through them. The orange / green are also connected with each other and currently can move freely through them, but when the seat switch is depressed (when you're sitting it), now both sides are connected as well. In the mower, below the seat. The purple wires are facing front and orange / green wires are facing the rear of the mower.

Seat Switch only has 2 prongs, one has two violets connected and the other has two orange / green connected. If you sit on the seat, all four of these are connected.

The Seat Switch in diagram shows "NC", normal closed (NO is normally open). This is closed if you're sitting on it.

Solenoid: In the diagram, it is at the bottom right, just above starting motor and left of the battery (it's not labeled there). If the small yellow and black wire have 12 volts DC, then the big red wires are connected, letting current go from the battery's red terminal to the starting motor's red terminal. The negative of the starter is connected to the engine frame itself and the frame is connected to the battery's negative ground.

You can have a 3 post solenoid or 4 post. Snapper Pro S200XT has a 4 post. In 3 post, the small wire 12v ground in a 4 post is now the frame itself in the 3 post.

On a solenoid, it doesn't matter which way the big red ones are hooked up as they're just joined by solenoid and doesn't matter which way the small ones are hooked up (that bring 12VDC to join the big ones)

So let's run through multiple scenario and show the direction of current (positive to negative - current flow, not electron flow). It's very interesting how this all works, and please correct me if I’m wrong in any of the scenarios. I will correct my notes that I keep at home

Scenario 1: Key is "Off"

Ignition Switch G & M & A are connected. M is connected to Ground. M is a white wire connected to ground at the ignition switch now. It then goes to port 5 of Time Delay module, but it also continues onwards to the magnetos. It is directly connected at Port 5, both white wires are connected at Port 5 (meaning they're connected with each other) This causes a short circuit in the magneto and it will not work, there will be no sparks in the spark plug, if the engine turns.

I don't understand why the A is also connected to Ground when the key is in "Off" position, what purpose does that serve?

 

[rajthepilot]

Scenario 2: Key is in "Start" position

Ignition Switch B & L & S are connected. B is a red wire that receives power from the battery via the 20amp main fuse. A big red wire goes from the battery to the solenoid, but then a small red wire from there goes via 20 amp fuse to the ignition switch's B terminal.

The current then leaves via L & A. L is orange / green, it goes to the PTO switch. If PTO switch is disengaged, it then moves to the Parking switch, if parking switch is engaged, it then moves to the seat switch (regardless of the position of the seat switch), current then moves to 'Right Hand Neutral Switch', if it is depressed with the lever resting on it, then current moves to the 'Left Hand Neutral Switch', and the wire now turns Green, if that switch is also depressed with the lever resting on it, then it moves via Blue wire to "Number 2 on the diagram". From there, the current flows to the parking switch (it doesn't connect to anything there, because parking brake is engaged and blue and orange/green circuit is open), the starter relay and port 1 of time delay module, the latter two are important now. Current flows via blue through the starter relay and out via green (in the process connecting the yellows), and over to Port 4 of Time Delay module. Because Port 1 and 3 are now powered as well via the Blue and Black wire, it means Port 2 and 4 are now connected and then current goes to the Ground from there. It also means Port 5 of time delay module is not connected to the Ground. White is also not connected to Ground in the ignition switch and thus magnetos are allowed to work and send electricity to spark plugs to produce sparks. The S wire from the ignition, goes via PTO switch, and if PTO switch is disengaged (pushed down, depressed), then the current goes through the Starter Relay and on to the Solenoid and it connects the big red wires above it, which send electricity to the Starter to turn over the engine.

Regarding Time Delay Module, if ports 1 and 3 are not powered, then 2 and 5 are connected, if 1 and 3 are powered, then 2 and 4 are connected and when 1 and 3 lose power, it takes a second or two for ports 2 and 5 to be connected. This is needed in case you jump from your seat while mowing, due to bumps in the lawn, the blue wire will lose power, which would connect ports 2 and 5, and that means white wire from the magneto is connected to the ground and it'll stop it from working. So that's why this time delay module exists. If you get up from the seat while the blades are turning, it'll turn off the mower in a second or two. There are other scenarios as well in which it'll turn off and I'll cover those shortly.
Scenario 3: Key is in "Run" Position

Ignition Switch B & L & A are connected. So B receives 12 volts via red wire and it sends it via A, violet wire to the seat switch and regardless of the position of the seat switch, because another violet is connected direcly to it, it then flows via 20 amp fuse, and then right away 15 amp fuse, it then becomes a gray wire and goes to the PTO switch. If PTO switch is engaged, then 2 gray wires have current and they leave it, one goes to the hour meter that shows how long the PTO has run, and the second gray wire goes to the PTO switch and a black wire from there goes to the ground.

If the PTO switch is not engaged, then the gray wire that comes from the 15 amp fuse at the PTO switch isn't connected to anything. The L wires goes to Fuel solenoid, so engine receives fuel because it is running and it also goes to the parking switch if PTO is disengaged and if parking is also disengaged, then it doesn't go anywhere else from there.

Now let's cover scenarios where it won't start or automatically shuts off

Scenario 4: Trying to Start with the PTO switch in engaged position (pulled up)

The yellow wire on 'COM' port at PTO switch will not be connected to the yellow wire and NC port, and it will not send power to solenoid via the starter relay, and engine will not start

Scenario 5: Trying to Start with either Parking Brake Disengaged, Left or Right Hand Neutral Switches not depressed, meaning both levers are not outward

If parking brake is engaged, the orange wire coming from PTO will not connect to the orange / green and if you follow the circuit, the blue wire will never get power and starter relay will never activate. Same for Left and Right Hand Neutral Switch.

Notice that you don't have to be sitting on the mower to start it. You just need PTO disengaged, so current can flow via yellow wire to the starter relay. And you need parking brake engaged, and Left and Right Hand Neutral Switches engaged (meaning the levers are sitting outward)

Scenario 6: Engine is running, PTO is disengaged, parking brake is disengaged and you get up from the seat and engine stops running

If engine is running and you're sitting, it means seat switch is closed and both orange / green on left and both violets on right are connected, and these are both 'hot wires', but same voltage, so we're okay here.

If PTO & Parking brakes are both disengaged, and you get up. Current is already not going from the Parking Brake Orange to Orange / green, but there is current in the Violet wires (both of them) at the seat switch and if you're sitting, that 12 volts is now going over to the orange / green on the left side of the seat switch, and now current flows this route (other times, during starting, it was the other way) to the parking brake and then via blue to Number 2 on the diagram, and then onto the time delay module. Since 1 and 3 are powered there, 2 and 4 are connected. So if you get up, the violet wires at the seat switch will not power the orange / green at the seat switch, thus the Blue at the parking brake will not be powered, and there will be no current at Number 2 in the diagram, time delay module won't be powered at ports 1 and 3 and so after a second or two, there will be a connection at time delay module's Port 2 and 5, meaning the white wire there gets connected to ground and it grounds the magneto, shutting the engine down

Scenario 7: Engine is running, PTO is disengaged, Parking Brake is engaged, Left or Right Hand Neutral Switch are disengaged and you get up from the seat and engine stop running

The orange at the Parking Switch sends power to orange / green, but because one of the neutral switches have an open circuit, 'Number 2' on the diagram won't get power and it'll cause Time Module Delay's Port 2 and 5 to be connected in a second or two, grounding the magnetos

Scenario 8: If PTO is engaged, parking brake disengaged, and you get up and engine stops running

With parking brake disengaged, orange / green won't receive power from the orange at parking switch, violets will be powered, but if you get up, the orange / green at seat switch won't be powered and thus the Blue at parking switch won't be powered and so there will be no power at Number 2 which will ground out the magnetos

Scenario 9: If PTO is engaged, parking brake engaged and you get up and engine stops running

If PTO is engaged, the yellow and orange / white wires coming to 'COM' port stop there and provide no current to Orange and yellow on the other side. The Violet wires do have power at seat switch. If you get up, the violets will not send power to the orange / green on the left side, which will not power the blue at the parking switch and then at number 2 in the diagram and that'll cause time delay module to connect 5 to 2 and grounds the magnetos

One thing to note here is the seat switch, current can flow in any direction depending on the situation. If you're not sitting on it, left side wires will stay connected and right side wires will stay connected, if you sit, then all 4 are connected. But if parking brake is disengaged and engine is running, the orange / green wires will get current from the violets, unlike the orange wire at parking switch providing it to orange / green when starting

Another point to keep in mind, you need current at Number 2 in the diagram for engine to start and continue running. If there is no current at 'Number 2' point, the time delay module in a second or two will connect 2 and 5 and ground the magnetos

So to figure out what will cause the engine to stop, figure out what will cause number 2 to not receive current, because that's how the engine stops while running (without you manually turning it off), so the safeties provide current to number 2 while the engine is running. If unsafe, they stop current to number 2 and engine stops because magnetos have been grounded.

So either you ground the magnetos by putting the key In "off" position, or the No Current at Number 2 position will cause the Time Delay to connect ports 2 and 5 and ground the magnetos and stop the engine from running

If parking switch is disengaged, but engine is running, then you need to sit on the seat to depress the seat switch, so that violets can send current to orange / green and then to blue wire out of parking brake switch to the power the 'Number 2' and I already explained why number 2 needs power for the engine to run

With key on, if you pull PTO switch, it will engage, even if you're sitting or not and engine running or not, and you'll hear the click (if engine isn't running, if engine running, then it's too loud to hear the click)

 

[rajthepilot]

So the only question remains for now is that when the ignition is off, G & M & A at the ignition switch are connected. But what purpose does it serve to connect the A?

 

[rajthepilot]

The diagram attached up in the message itself isn't showing anymore, so I'm adding it as an attachment