Scag Wildcat 2007 no juice to starter

KlinkSanford

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I have a 2007 Scag Wildcat STWC52V-25KA, 52" with a Kawi 25hp which I bought from my neighbor about two months ago. The motor and the deck are newer like from 2014 and it sat like 2 years unused, so I bought it from him. I changed the engine and hydraulic oils & filters, changed the center spindle and tapered hub, the idler bearings, springs, and put in a new negative wire to the battery and cleaned the connections on both ends, and I did a few other minor things, and had my 15 year old son mow the front 1/3 of my 5 acres. The machine ran great. It started to rain towards the end, so he put the machine away in the barn. The next day I went to take it out of the barn and it cranked for one split second, then it clicked like the battery was dead. Then it did nothing, no sound no nothing.

I took out the multimeter and checked the battery and it was fully charged 12.77v. I got my multimeter out and tested all of the safety interlock switches, the seat switch is bypassed it is jumped, I checked it and it has continuity, I checked the brake switch, and the two arms switches (they are the same part number according to the part manual) and they all had continuity, HOWEVER, curiously, although they are the same part number the two arm switches have continuity when not pushed in, and the brake switch has continuity when pushed in. My neighbor says they were the arm switches were the opposite before. Anyhow, I thought that that should not affect anything since it just means the arms have to be in one position or the other to start and it does not start in any position. I tested the relay switch thoroughly according to this video and it passed on every test.





I then tested the starter switch and it passed. I hooked up the multimeter black lead to the battery negative and the red positive lead to the loose green wire at the starter solenoid and only got .560 volts when I turn the key, and it makes no difference how the interlock switches are set. I reconnected the green wire to the solenoid and moved the red multimeter lead to the red battery wire connected on the starter, and got 12.67v w. Then I turned the key switch to start and the voltage dropped to 1+ volts. I also borrowed a new PTO switch from my neighbor and tried with it and no change.


Any suggestions would be greatly appreciated.
 

TheVirginian

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the one (two rather) thing i didn't see you say you checked and maybe yours DOESN'T have them like my Turf Tiger does, but the main fuse and the 2nd fuse at the control box.
 

Rivets

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If your battery voltage dropped from 12V to 1V when you turned the key switch, most likely your battery is junk. Yes, it can happen that fast.
 

KlinkSanford

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the one (two rather) thing i didn't see you say you checked and maybe yours DOESN'T have them like my Turf Tiger does, but the main fuse and the 2nd fuse at the control box.


It has two fuses and I checked them and they are intact.
 

KlinkSanford

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If your battery voltage dropped from 12V to 1V when you turned the key switch, most likely your battery is junk. Yes, it can happen that fast.


It drops to 1 volt at the end of the run of the battery red cable at the starter when you turn the key to start. The battery itself remains at 12.7 volts. I also jumped it with a Group 29 battery and it does the same thing.
 

Rivets

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You didn’t say that, so I assumed you meant at the battery. In your case you now have to check voltage at the solenoid. If your solenoid is starter mounted, it is probably bad. If your solenoid is remote mounted check voltage on both sides of the large terminals.
 

bertsmobile1

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First thing can you turn the engine over by hand ?
If not remove the spark plugs & try again
Do not crank.
If the engine has hydro locked, the starter is not strong enough to compress the petrol in the cylinder till it smashed the head or blows the head gasket out.
If the engine is hydro locked then it will be full of fuel which can catch fire if expelled by cranking & on a hot day catch fire.

Thus the electrics could be fine.

You have 2 set of safety switches.
the cranking set passes 12V from the key switch through the PTO & Parking brake switch then to either the starting solenoid or the starting relay.
ALL other safety circuits are GROUND circuits .
On some ZTR's the lap bar switches will make a ground circuit to a starting relay which in turn sends 12V to the starter solenoid.
Thus the starting relay can be switched by either or both the power trigger & the ground trigger .
All of the actual switches are simple sliding contact switches which can be either NO or NC.
If a switch has 4 terminals then it will have a pair of each if only 2 terminals it is usually a NO type.

If you have a circuit diagram, replace the relay with a jumper wire.
Usually I pull the key switch plug off then jump the B & S together.
This will then give you 2 hands free to probe the wiring.
In my case I pull the switch plugs one at a time, jump the plug and continue along this path till the engine cranks.
The jump that cranks the engine is usually the duff switch.

Big warning
If you are not sure which wires are the magneto kill wires then pull the blower housing off & remove the magneto kill wire because the briefest amount of battery voltage sent down the kill wire will destroy the chip in the magneto coil $$$$$$
 

KlinkSanford

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To clarify what I wrote in the OP:

I hooked up the multimeter black lead to the battery negative and the red positive lead to the loose green wire at the starter solenoid and only got .560 volts when I turn the key, (in other words, the green wire supplies the power to the solenoid to start the engine and it should read 12v when you turn the key, and it only reads .560 volts.) and it makes no difference how the interlock switches are set. I then reconnected the green wire to the solenoid and moved the red multimeter lead to the red battery wire connected on the starter, and got 12.67v w. (In other words there are 12volts at the battery stud connection at the starter), but when Then I turned the key switch to start and the voltage dropped (at the same battery wire connected on the starter battery stud connection) to only 1+ volts.


Secondly, the starter is new. Nevertheless, yesterday I removed it and bench tested it off the engine it works perfectly.
 

KlinkSanford

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I can't get the reply with quote to work, nor the highlighting to change colors or to bold, so I respond to you with ------( my response in quote marks)

1) First thing can you turn the engine over by hand ? -------(Yes it turns by hand)
If not remove the spark plugs & try again
Do not crank.
If the engine has hydro locked, the starter is not strong enough to compress the petrol in the cylinder till it smashed the head or blows the head gasket out.
If the engine is hydro locked then it will be full of fuel which can catch fire if expelled by cranking & on a hot day catch fire.Thus the electrics could be fine.

2) You have 2 set of safety switches. the cranking set passes 12V from the key switch through the PTO & Parking brake switch then to either the starting solenoid or the starting relay.
ALL other safety circuits are GROUND circuits . ------ (If I am reading the electrical diagram correctly all the switches (4) the PTO, Parking brake, LH & RH steering neutral switches are all positive, they have red wires, though there is an orange wire on the RH neutral switch that goes into the module.) On some ZTR's the lap bar switches will make a ground circuit to a starting relay which in turn sends 12V to the starter solenoid.Thus the starting relay can be switched by either or both the power trigger & the ground trigger . All of the actual switches are simple sliding contact switches which can be either NO or NC. If a switch has 4 terminals then it will have a pair of each if only 2 terminals it is usually a NO type.

3) If you have a circuit diagram -----(yes I do have the diagram) , replace the relay with a jumper wire. Usually I pull the key switch plug off then jump the B & S together. ------( Do you mean that instead of replacing the relay with a jumper wire, you just pull the key switch plug? Then you use a hand held remote starter switch hooked up direct from the battery positive post to the starter solenoid? ) This will then give you 2 hands free to probe the wiring.
In my case I pull the switch plugs one at a time, jump the plug and continue along this path till the engine cranks. The jump that cranks the engine is usually the duff switch.

Big warning
If you are not sure which wires are the magneto kill wires then pull the blower housing off & remove the magneto kill wire because the briefest amount of battery voltage sent down the kill wire will destroy the chip in the magneto coil $$$$$$ -----( by magneto you mean the charge coil? The only wire that I see that kills the charge coil is in the key switch, so if the key switch connector is disconnected, I do not see how I could electrify the charge coil, right?)
 

bertsmobile1

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I can't get the reply with quote to work, nor the highlighting to change colors or to bold, so I respond to you with ------( my response in quote marks)

1) First thing can you turn the engine over by hand ? -------(Yes it turns by hand)
If not remove the spark plugs & try again
Do not crank.
If the engine has hydro locked, the starter is not strong enough to compress the petrol in the cylinder till it smashed the head or blows the head gasket out.
If the engine is hydro locked then it will be full of fuel which can catch fire if expelled by cranking & on a hot day catch fire.Thus the electrics could be fine.

2) You have 2 set of safety switches. the cranking set passes 12V from the key switch through the PTO & Parking brake switch then to either the starting solenoid or the starting relay.
ALL other safety circuits are GROUND circuits . ------ (If I am reading the electrical diagram correctly all the switches (4) the PTO, Parking brake, LH & RH steering neutral switches are all positive, they have red wires, though there is an orange wire on the RH neutral switch that goes into the module.) On some ZTR's the lap bar switches will make a ground circuit to a starting relay which in turn sends 12V to the starter solenoid.Thus the starting relay can be switched by either or both the power trigger & the ground trigger . All of the actual switches are simple sliding contact switches which can be either NO or NC. If a switch has 4 terminals then it will have a pair of each if only 2 terminals it is usually a NO type.

3) If you have a circuit diagram -----(yes I do have the diagram) , replace the relay with a jumper wire. Usually I pull the key switch plug off then jump the B & S together. ------( Do you mean that instead of replacing the relay with a jumper wire, you just pull the key switch plug? Then you use a hand held remote starter switch hooked up direct from the battery positive post to the starter solenoid? ) This will then give you 2 hands free to probe the wiring.
In my case I pull the switch plugs one at a time, jump the plug and continue along this path till the engine cranks. The jump that cranks the engine is usually the duff switch.

Big warning
If you are not sure which wires are the magneto kill wires then pull the blower housing off & remove the magneto kill wire because the briefest amount of battery voltage sent down the kill wire will destroy the chip in the magneto coil $$$$$$ -----( by magneto you mean the charge coil? The only wire that I see that kills the charge coil is in the key switch, so if the key switch connector is disconnected, I do not see how I could electrify the charge coil, right?)

Sorry,
I got lost in my own post.
For diagnosis only I jump the key switch plug.

Now you have expanded things a bit I see what is happening.
When you test the key switch > PTO > lap bar > lap bar > module circuit , do you get 12 V (ish) at the wire going into the module ?
If so the cranking circuit is good.
Then check the seat switch wire into the module
If they both test good then the module or the cranking relay is duff
This is when I jump the cranking relay.
If the engine cranks, then the module is duff and that automatically makes me double check because the modules are not cheap.

As for the ignition, it consists of a coil for each plug mounted externally to the flywheel & a magnet.
Inside the coil is a micro chip that times the spark
It is on the ground side because it grounds the coil.
I do not have a wiring diagram for your exact mower .
On the 4 pin safety switches there are 2 sets of contacts .
One is 12V which is for cranking and the other is ground which is for shutdown.
If the 12V gets connected to the ground then the chip in the coil gets fried.
 
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