425 will not shut off

[oldnslo]

Good friend has a 425 that will not shut off unless we disconnect the battery cables. We have tried disconnecting the ignition switch with no change. When you touch the battery terminal their is a spark and an audible click almost like the starter solenoid but it isn't.

Any suggestions on where to start looking or where to get an electrical diagram for this machine.

TIA

Roy

 

[beenthere]

Does it start up normal when reconnecting the battery cables?

I'd suspect a faulty ignition module. or maybe the ignition module.

A tech manual is available on CD or booklet that will give the wiring diagram.

A portion of the system operation dialogue. See the 4th line down.

 

[oldnslo]

Thanks beenthere,
I suspected their was a relay being powered up when we connected the battery but wasn't sure what it was for. Will have to see if the local dealer will give us a peak at the wiring diagram or not.

Yes it starts and runs fine, it just won't shut down even with the PTO engaged and you get off the seat. I am 99.99% sure it is an electrical issue but where to start looking is the $64 question.

Roy

 

[beenthere]

Which part of the diagram do you want to peek at? Here is the ignition schematic up to s/n 070,000

 

[oldnslo]

Thanks been there, looks like that schematic shows the start circuit with all of the safety switches. Just have to start chasing wires and see if we can determine what component is faulty.

Roy

 

[beenthere]

Is the s/n above or below that 70,000? That is mfg before '99

Maybe you will find a loose wire or connection. Seems starting at the ignition switch as turning it off should start a chain reaction that shuts down the engine. There are a number of troubleshooting items, none of which specifically addressed the engine not shutting down. Only start-up and running problems.

 

[beenthere]

If below 70,000 then this shot of the component locations may help. A1 is the Ignition Delay Module and A2 is the Ignition module located on the engine. I'd start with wiggling the components and wire connectors leading to them while key off and engine still running.

 

[oldnslo]

thanks beenthere,
s/n is in the 40,000 so this info is greatly appreciated. Friend is out of town on family business but thought he would be back tomorrow. If not I will probably take my BX over and mow his hayfield/ lawn.

Roy

 

[Greenblood2011]

Look for the diode by the ignition relay, it's probaly bad. That diode stops power from backfeeding the relay causing it to stay on. It's shown in the wire diagram. Good luck

 

[beenthere]

Greenblood2011

Sounds like you are onto the possible problem.
Would the ignition LED (lit or unlit) on the control board be a clue to a bad diode?

Is the location of that diode shown in the tech manual? Or just trace it along the 706 pink/black wire shown in the schematic.

This is what the tech manual says about tracing the signal through the ignition relay (doesn't point out the diode tho).

With the operator off the seat and the key switch in the
run position, current flows from key switch terminal B to
terminal A, power fuse (F4), ignition relay terminal 87,
brake switch (S3) (brake pedal depressed), PTO switch
(S4) (PTO disengaged), ignition relay coil terminal 85, <<--( diode here)
and ignition LED(E1). The ignition LED indicates that
power is available to the ignition relay coil. With the
ignition relay energized, current (C) flows to the PTO
switch, and ignition delay module. The ignition delay
module allows........

 

[Greenblood2011]

It's probly easier to just trace the wire... Deere puts there diodes any where they fit. It'll most likely be small about an inch square with two wires that plug in. Could be black or yellow. Check and make sure he didn't bypass the seat switch, that could also cause this issue. Let me know what you find.

 

[beenthere]

Update
Just heard that

....... it was the starter relay and diode. Not sure which failed first but they both had to be replaced.

Wanted to see this to some kind of closure.

 

[Gittyup]

so was the starter runing all the time?

 

[regalgsguy]

Hello all. I am restarting this thread cause my 425 is not shutting down too. I can completely disconnect the key switch and board from the tractors harness, turn on the pto switch without sitting on the seat and the engine continues to run. That diode "rectifier kit" that goes in the tractors harness, where exactly does it go? Is that diode for engine shutdown? The tractor is a early serial 425.

 

[beenthere]

:welcome: to TBN

You say "early", is s/n older than 033626 ? If so, then maybe need to check out the "carburetor vent solenoid". If newer than that s/n, then check out the "fuel shut-off solenoid".

 

[regalgsguy]

The serial is in the 12000 range so it has a vent solenoid. The solenoid tubes have been disconnected and the carb revented directly to the airbox with a new tube bypassing the solenoid due to it having heat up failure. The only way I can stop the engine is by disconnecting the little red power wire from the battery positive lug on the starter to the time delay module. Turning off the key switch does shut off everything but the engine ignition circuit.

 

[Richard001]

Looks like it's time to replace the delay module and the diode that is closest to the seat switch.

Richard

 

[regalgsguy]

For twenty bucks it is worth a try replacing the time delay. Should I assume the diode near the seat switch is buried in the harness somewhere? Is this problem common in JD's? I work on 100's of craftsmans and other cheap tractors every year and know the electrics like the back of my hand, but these JD circuits I have yet to study and fully understand.

 

[regalgsguy]

Its been awhile since I replaced the module and can confidently say that was the problem. All is well now.

 

[Richard001]

Good to have success and closure.

Good job.