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mlwheat

520 xi shutting down

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This morning I tried to use my 520 xi to clear my driveway.  It has a two-stage snow thrower attachment.  The engine started just fine, but when I released the key, the engine kept shutting down.  I discovered that if I held the key in the Start position, it continued to run.  However, if I then lifted my foot off the brake pedal (must be depressed to start engine), it would shut down.  I'm guessing that perhaps the ignition switch has a problem or one of the safety shutoffs is engaging.  The ignition switch was replaced a couple of years ago, so it shouldn't be defective, but I've tried every available easy fix, with no luck.  Any suggestions?

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Welcome to the forum.

Be careful checking this out because the ignition is self-powered and it any voltage gets to the ignition system it will release the magic smoke. The ignition wire from the engine is simply grounded to the chassis to shut the engine off so suspect one of the safety switches is causing this problem.

The kill relay needs to be powered to open the relay contacts so the ignition will work.

The interlock relay, seat switch, pto switch and brake switch control the kill relay.

Check out the "Run Circuit" in this detailed wiring diagram for the 1999-2001 models.

It your model year is different let us know.

Compare the "Start" diagram to the "Run" diagram to see why it runs in Start position but not in the Run position.

Garry

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I would start with the seat switch as I have had to replace two of them on my three 5xi. It is simple to bypass with a jumper wire. If not that one, start checking the other safeties like Garry suggested.

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:WRS:

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I had the exact same problem and symptoms with mine. Bad ignition switch

SWITCH-IGNITION 92-6785 $51 on Amazon

Edited by WNYPCRepair
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In addition to what Brian and John said, there are three relays that control a lot of the safety circuits.  They are on the firewall and they are all identical.  One could be bad.  Find which one is in the starting circuit and switch it around to see if the problem goes away.  If it goes away, switch it back to the original position and see if the problem back.  If it doesn't go away, then it is either the ignition switch or the wire at the back of the switch connector in the "run" position.  I do not think it is a safety switch as the engine will not even crank with one of them not working.

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4 hours ago, doc724 said:

In addition to what Brian and John said, there are three relays that control a lot of the safety circuits.  They are on the firewall and they are all identical.  One could be bad.  Find which one is in the starting circuit and switch it around to see if the problem goes away.  If it goes away, switch it back to the original position and see if the problem back.  If it doesn't go away, then it is either the ignition switch or the wire at the back of the switch connector in the "run" position.  I do not think it is a safety switch as the engine will not even crank with one of them not working.



In my case, the contacts inside the switch were all rusted. The symptoms were exactly as listed. It was right after my broken axle, and I was teaching my wife how to start and use it. I got frustrated thinking she was doing something wrong. I finally hopped over and figured out it was the switch

Edited by WNYPCRepair

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Thanks for all the feedback thus far.  To summarize, it seems that there are 5 possible culprits:

1. Seat Switch

2. Brake Pedal Switch

3. PTO Switch

4. 3 Relays (Start-Kill-Interlock)

5. Ignition Switch

My (amateurish) analysis thus far:

1. I neglected to inform you that I had bypassed the seat switch years ago by inserting a jumper wire.  Yesterday, I removed the wire to see whether that had any effect.  It did, the tractor would not start at all without it.  I replaced the wire, and now the tractor will start again, although it continues to shut down.  Thus, I don't think this switch is my problem.

2. The brake pedal switch seems to be working properly.  The tractor cannot be started without depressing the pedal.  Even if I keep it depressed, when I turn the key to start, and then release the key, the tractor stops running.  Again, I don't think the brake switch is my problem.

3. As for the PTO switch, the tractor will not start unless it the PTO button is depressed.  If I start the tractor and keep the key in the start position, then pull the PTO button, the snow thrower starts to run for a split second, but then the tractor shuts down again.  This switch seems to be working properly, although I guess I can't be certain.

4. I haven't yet tried switching the relays to try to determine if one is bad, but I will do so momentarily.

5. The ignition switch was replaced a few years ago, but it could have gone bad in the interim.

I realize that problems like this sometimes need a "trial and error" approach.  However, if I find that the relays seem to be ok, then I will replace the ignition switch.  If then I still have the same problem, I will report back.

Thanks again,

Mike

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2 hours ago, mlwheat said:

Thanks for all the feedback thus far.  To summarize, it seems that there are 5 possible culprits:

1. Seat Switch

2. Brake Pedal Switch

3. PTO Switch

4. 3 Relays (Start-Kill-Interlock)

5. Ignition Switch

My (amateurish) analysis thus far:

1. I neglected to inform you that I had bypassed the seat switch years ago by inserting a jumper wire.  Yesterday, I removed the wire to see whether that had any effect.  It did, the tractor would not start at all without it.  I replaced the wire, and now the tractor will start again, although it continues to shut down.  Thus, I don't think this switch is my problem.

2. The brake pedal switch seems to be working properly.  The tractor cannot be started without depressing the pedal.  Even if I keep it depressed, when I turn the key to start, and then release the key, the tractor stops running.  Again, I don't think the brake switch is my problem.

3. As for the PTO switch, the tractor will not start unless it the PTO button is depressed.  If I start the tractor and keep the key in the start position, then pull the PTO button, the snow thrower starts to run for a split second, but then the tractor shuts down again.  This switch seems to be working properly, although I guess I can't be certain.

4. I haven't yet tried switching the relays to try to determine if one is bad, but I will do so momentarily.

5. The ignition switch was replaced a few years ago, but it could have gone bad in the interim.

I realize that problems like this sometimes need a "trial and error" approach.  However, if I find that the relays seem to be ok, then I will replace the ignition switch.  If then I still have the same problem, I will report back.

Thanks again,

Mike

Down the demystification guide from here (RedSquare) and using a multi-meter, as you have been doing, 1 by 1 start checking for shorted/open circuits, it took me a little bit with a 520H I picked up a couple years back that had been wiring hacked but I succeeded in finding the root cause and repairing to factory functioning, I know the xi series is a bit more complex but as I had a couple of those too, and a bad/loose ground or chaffed/shorted wire could cause the ignition switch to burn out once again, Jeff.

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This afternoon, I switched the relays, to no avail.

 

Next I will try replacing the ignition switch.

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If this is the correct ignition switch for your model of tractor the procedure for testing the switch is posted here. Click on the picture first.

Garry

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I am pleased to report that I have replaced the ignition switch, and all is working properly again.  Thanks to everyone for your help.

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