Walk behind unit electrical problem

[Richie F]

Simple solution would be to put a momentary contact switch on the mag. kill line to ground. No big voltage or current in this circuit. Bypass all the stuff. Nice big red button on the dash. Probably not legal in all 50 states though.

I was thinking of putting a switch in line to the Mag but would like to find the reason for the problem first.

 

[Richie F]

I would use an OHM meter and find what is connecting the kill wire to ground to kill the engine when pto switch is pulled to engage the clutch.

I'm using a VOM. That's what I used to check the diode that goes to negative lead of the clutch.

 

[Richie F]

a wiring diagram is can be found on partstree under the model and serial number for that machine

Please read my first post, last sentence.

 

[Richie F]

Put everything back in place all safety switches and see if the problem goes away. Also at 3.3 ohms is high for the clutch so soon as you apply the clutch it draws out all the battery and could be your problem. Replace the safety's then go from there one leads go to the others failure.

My friend owns a lawn service and worked very late Thursday. Didn't get to do what you have suggested.
Wanted to first verify all switches and then hook everything back up.
I thought the ohm range for a clutch was 2 to 4 ohms.
This is a walk behind that doesn't have a battery, only has a rectifier to supply voltage.
I should measure it and see its output though. Then find a spec on it.

 

[Richie F]

In which case my first reply is still valid, the PTO switch will have several safety circuits running through it and they are very difficult for people with no idea about what they are doing or basic DC electronics to bypass properly.
As you might have already guessed I do not have much time for people disabling safety switches


So if you have the wiring diagram just follow the kill wire back from the coil to where ever it grounds, and there will be a lot of places where this can happen.
If necessary print it out a couple of times, pinch a coloured pencil from one of the kids and trace over the kill wires for each situation or use different coloured wires for PTO on & PTO off
IF there is no pin out for the PTO switch then pull it out and measure across the contacts.
It is a simple sliding contact switch that connects left to right and generally all of the middle row will be tied together.

"As you might have already guessed I do not have much time for people disabling safety switches"
I wasn't aware of this.

I have used the wiring diagram to trace out the Mag wire circuit. That's where I found the 600v/6a diode in the ground lead from the clutch. Thought it could have been bad and when I checked its directions it showed good.

My friend has another identical machine with the safeties by passed and it operates with no problems. Start it up and engage the blades and it doesn't shut down.

 

[bertsmobile1]

It will be in the PTO switch.
There should be a kill wire that is active when whatever it uses to work out you are not deceased is in the "no one is here mode"

 

[Richie F]

It will be in the PTO switch.
There should be a kill wire that is active when whatever it uses to work out you are not deceased is in the "no one is here mode"

"It will be in the PTO switch."
If you are talking about the diode, it is in the harness not the switch.

"There should be a kill wire that is active when whatever it uses to work out you are not deceased is in the "no one is here mode"
Could you write this differently ? Really don't understand what your trying to say.

 

[Richie F]

Here is the wiring for this machine.

https://www.partstree.com/models/sw...kawasaki-sn-j6100001-j6199999/wire-harness-9/

Going to contact SCAG at 1-800-937-7279 to ask them what the switch function is in the circuit.
Are they all NO (Normally Open) or are some NC (Normally Closed).
That will help in tracing out the ground circuit.

 

[Richie F]

This getting interesting.
Just talked the SCAG.
They said there is a safety in the CONNECTOR PLUG for the operator presence switch. If that plug is not on the switch itself it can cause a ground to the Mag when the PTO is engaged.
The person also said there is a safety built into the PTO switch, but couldn't tell me how to test it.
The rectifier puts out AC voltage not DC like you think it would.
I said it's a rectifier. Its job is to change AC to DC like the alternator on your car. The person said "That's the way it works"
So why is it if you put 12V to the clutch coil to test it, it works. The answer given "Your fooling the clutch"
I have a bad taste in my mouth about parts of this conversation.
I'll get back when I look at both parts.

 

[bertsmobile1]

I was going to leave this alone because of the belief that if you can not work out how to bypass things that are there for your own safety then you should leave them alone.
If understanding how they work is beyond you mental capacity then operating the machine safely is probably beyond your mental capacity as well.
None of them will stop you using the machine to it's full capacity if they are working and there is no real reason to bypass them.
The pto switch should be shown in the wiring diagram.
They are generally shown turned off so you continuity test them off and then on then go back to the wiring diagram.
It is a switch so some pairs will be open & some will be closed depending upon which position the switch is in and I have already told you it switches left to right and if it is a 3 row switch the middle ones are all connected together.

As for the operator presence switch plug, that is common now days to prevent the red neck, brain dead simply unplugging one then getting injured.
The reason is because some idiot moron bastards pulled them out , got hurt, then got massive damages payments by convincing a judge that it is possible for the plug to "fall out " without the operator knowing it.
So a simple plug that was cheap & easily available became very expensive & very hard to get one
Some companies have gone the other way by making safety switch a normally closed switch.

If you thought that a Scag employee or dealer was going to tell some one over the phone how to bypass the safety features, many of which are a legal requirement, then you must be incapable of reason.
The factory fits safety equipment then I tell you have to defeat it, you get hurt then I have left myself open to a massive law suit.

So naturally they will not tell you how to do it, not unless they are barking mad.
They might have told you how to test the various parts are working but that would be the limit of what a reasonable person would expect from them.

And you are yet to divulge why it is vitally important that your friend gets the safety switches bypassed on his mower.,
And have another thought, does his wife & children love you to the point that if he looses a hand or foot using the mower that you made "legally unsafe to operate", none of them will yield to the ambulance chasing lawers promising them they can get millions from you & Scag in compensation ?

How strong do you think your friendship is ?
lots of folks in the poor house because a close & trusted friend was not quite as close when an oppertunity to make a big amount of money presented itself.