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Personally I would like to disable the entire safety interlock circuit but my 17 year old is going to start doing so mowing so I will leave it intact.

For a long, long time every now and then when I turn the key to start the tractor, nothing happens, not starter engaging ...noting. Sometimes if I sit there is push hard on the clutch pedal it will engage; sometimes if I sit and rock the tractor a bit it will engage and then sometimes nothing works. Tonight nothing was working and I gently pushed on the mower PTO and just as I started to push with resistance it cranked.

Recently the seat safety switch stopped working and I could get off the tractor to move a branch without it stopping. Yeah! Tractor seemed to run just fine without the switch working.

I believe it is a safety switch issue but how do I determine which one? My service manual says I have three switched the seat, drive and PTO. It doesn't show their locations ...yea the seat is self explanatory.

There is a switch I know if that operates when the brake is engaged. Is it the drive safety switch.

There is a switch that the PTO lever hits and is located by the battery. I would guess it is the PTO safety switch.

How can I isolate the problem to find which switch? The PTO is high on my list and maybe I could jumper the connector? If I remove the connector does that make it a dead starting situation?

well...first.... you'll need a wiring diagram so you can simplify.....second ..there's start switches and run switches...generally with switches ..you'll want to remove wires ..set your volt meter to continuity.....touch your voltmeter leads ..and flick the switches slow and fast to see any discrepancies .....in the broad picture ..basically you want to put your red [hot] lead of voltmeter on the starter solenoid small wire [activation hot lead] and the black [ground] to the negative batt. terminal.....have a helper on this one!.....then turn your key all the way to start and hold it as you clutch on/off and seat on/off to test switches....switches can close circuits and open them.....so you can test each switch as to what circuit its controlling [start or run]....also if you deactivate the safety switches.... teach your son the proper safety protocol to stay safe ...about 20 times in a row.. so its automatic in his head... hope i helped....if you need clarification..just ask..get back to us with any new info:smile:......thats one neat old tractor you have!

reddragon said:

well...first.... you'll need a wiring diagram so you can simplify.....second ..there's start switches and run switches...generally with switches ..you'll want to remove wires ..set your volt meter to continuity.....touch your voltmeter leads ..and flick the switches slow and fast to see any discrepancies .....in the broad picture ..basically you want to put your red [hot] lead of voltmeter on the starter solenoid small wire [activation hot lead] and the black [ground] to the negative batt. terminal.....have a helper on this one!.....then turn your key all the way to start and hold it as you clutch on/off and seat on/off to test switches....switches can close circuits and open them.....so you can test each switch as to what circuit its controlling [start or run]....also if you deactivate the safety switches.... teach your son the proper safety protocol to stay safe ...about 20 times in a row.. so its automatic in his head... hope i helped....if you need clarification..just ask..get back to us with any new info:smile:......thats one neat old tractor you have!

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Yeah I agree with also. You want to use an ohm meter to check for any resistance on the switches. If any of the switches indicate infinite resistance in the closed position the switch is bad.

Looks like I have my work cut out for me. First I thought it was the PTO safety switch because if I jostled the PTO lever it would start. Then it wouldn't work that way. If I jiggled the key it would start. Hm????? The key is very, very worn and maybe the ignition switch? Heck on a 1986 tractor it may be several of the safety switches.

Now were did I last leave my meter?

reddragon said:

well...first.... you'll need a wiring diagram so you can simplify.....second ..there's start switches and run switches...generally with switches ..you'll want to remove wires ..set your volt meter to continuity.....touch your voltmeter leads ..and flick the switches slow and fast to see any discrepancies .....in the broad picture ..basically you want to put your red [hot] lead of voltmeter on the starter solenoid small wire [activation hot lead] and the black [ground] to the negative batt. terminal.....have a helper on this one!.....then turn your key all the way to start and hold it as you clutch on/off and seat on/off to test switches....switches can close circuits and open them.....so you can test each switch as to what circuit its controlling [start or run]....also if you deactivate the safety switches.... teach your son the proper safety protocol to stay safe ...about 20 times in a row.. so its automatic in his head... hope i helped....if you need clarification..just ask..get back to us with any new info:smile:......thats one neat old tractor you have!

Click to expand...