OT mostly - what's wrong with my lawn mower?

[Tony Ennis]

I have a John Deer L120 mower. The wife started it without issue and drove it to the compressor so I could add air to the tires. She shut it off. When I was done inflating the tires, it would not start. Not a grind, not a click, not a whirrr. The headlights don't come on. Wholly inert. I put the battery on the charger and it seems to have a full charge.

Possibilities:

1. Corrosion on the battery terminals
2. A broken wire.
3. The keyswitch is worn out. (it includes the light switch) Even though the key is not reversible, I kinda noticed it goes in and turns either way.
4. Some safety mechanism has failed (though the last time this happened the mower would grind, there was simply no spark)

I found a fuse and examined it. Looks ok.

Ideas on how to troubleshoot?

[CarlByrns]

Basics. Make sure there is a solid connection between the battery and the frame and then, using a test light (clipped to ground), start at the battery positive post and see where the electricity stops by going from point A to B to C to D. I'll bet it's the ignition switch because they tend to take a beating on power equipment, but it could be a bad wire or loose connection.

[EddyCurr]

1. Good battery should have 2.1V per cell, ie: 6.3V or 12.6V.
   6.0V or 12.0V is low
   .
2. Just for the sake of maintenance, clean both the terminals & posts.
   Remove neg first, followed by pos. Use some emery cloth or similar
   abrasive to get through any oxide. Apply grease and reconnect - pos
   first, followed by neg.
   .
3. Switch on and try starter.
   .
4. If no result, check whether lights illuminate. If yes, check circuit
   to starter solenoid. If no, go back to check for power from battery
   cables to switch.

If no luck after the above, post again.

.

[Willy]

What happens when you bypass the starter solenoid by jumping the battery to starter posts?

It probably looks somewhat like the one in the pic below.
Usually one of the small terminals is a ground, the other small one is 12 volts from the key switch. You should have bat. voltage there when trying to start. This closes the switch inside and connects the starter cable to the battery cable side of the solenoid switch. Jumping the two posts at least assures that the battery and starter are operative.
Do the easy and basic stuff first and let us know.

[OwenG]

Hi. Is there an isolation switch attached to the seat that is not functioning correctly? One I used to use was intermittent and could cause problems

[mixdenny]

Safety switch on the seat or the blade engage lever. Both of them failed on my Honda over the years. Same symptoms as your mower, although mine does not have lights. I couldn't even get to the blade switch, had to jumper it. A wiring diagram should be in the manual, it might be online if you don't have it. Dennis

[Danl]

What happens when you bypass the starter solenoid by jumping the battery to starter posts?

It probably looks somewhat like the one in the pic below.
Usually one of the small terminals is a ground, the other small one is 12 volts from the key switch. You should have bat. voltage there when trying to start. This closes the switch inside and connects the starter cable to the battery cable side of the solenoid switch. Jumping the two posts at least assures that the battery and starter are operative.
Do the easy and basic stuff first and let us know.

I have a JD Model 170, and when my solenoid went out, it would just click, but not crank. I was actually able disassemble and rebuild it, but JD would probably recommend replacement, for around $30 +S&H on eBay, but I'm too tight fisted with my $, and the grass was growing fast. Still is. Only things growing faster around here are the weeds.

Dan

[PStechPaul]

It is possible for a battery to fail completely like this. It may show a voltage on the charger, but won't accept any current. A good test is to connect a 12V headlamp across the terminals. Or, you can just use jumper cables from your car to the battery when it's in the mower. I had a car battery fail like this five years ago. All seemed fine on a 60 mile trip. Parked, got out, decided to find a better spot. Started right up, parked elsewhere, went away for a few hours. Came back, totally dead. Got a hot shot, started up, cables off, running OK, thanked the guy and he drove off. Touched the brake, engine died. Probably an internal connection broke or fused open. New battery is still going strong, but after five years, probably time for a new one, at least before winter.

[Mike Burdick]

Check the oil level, if the oil is low, some engines have a switch that prevents it from starting.



From the user manual...

Engine Will Not Start
- Brake pedal not depressed.
- PTO is engaged.
- Spark plug wire is loose or disconnected.
- Improper fuel.
- Plugged fuel filter.
- Defective safety switch.
- Electrical problem - See Electrical Troubleshooting Section

From the Electrical Troubleshooting Section

Starter Does Not Work Or Will Not Turn Engine
- Brake pedal is not depressed.
- PTO is engaged.
- Battery terminals are corroded.
- Battery not charged.
- Blown fuse.
- Fusible Link in starting circuit is blown - See your authorized dealer

[lakeside53]

Probably an "open" in the series safety switches circuit. Find the "service connector" point and bypass to prove.

[WilsonT]

Typically when the lights won't come on, it indicates a bad connection between the battery and the battery cables (although some mowers have the lights run off of the alternator such that they won't come on when the engine is not started to prevent them from draining the battery). A volt meter could still show a full charge charge because the amperage draw is low. I would try using another battery (from another vehicle) to try to give the mower battery a boost. If you get a response, clean the terminals. If not, the problem is probably in the solenoid (as mentioned above).

[firbikrhd1]

I was running my dad's L39 Kubota tractor which he maintains meticulously. Shut it off for lunch, and like you when I came back to it nothing. Checked the battery, terminals looked good voltage OK, checked fuses, wiring, even took the dash apart thinking it was the ignition switch. All checked out good. Finally in desperation I took the ground terminal off the battery and wipes some minute amount of what looked like gray grease off it, reinstalled it and it fired right up. Turns out there is corrosion, or a form of it that looks nothing like the common corrosion usually seen and in fact is near invisible. I cleaned both terminals thoroughly and it hasnt missed a beat in two years since.

[Glug]

Any update?
The lack of headlights suggests it does not relate to the ignition switch, etc. I have observed the same sort of corrosion described by others, in autos. The battery connection can supply enough amperage to light the dome light, the door buzzer, and even the radio. But as soon as you try and engage the starter or headlights, that feeble current path fails and you lose it all. A quick fix is to twist the connectors on the posts, by hand or with pliers, but a proper cleaning is best.

[CarlByrns]

Any update?
The lack of headlights suggests it does not relate to the ignition switch, etc. I have observed the same sort of corrosion described by others, in autos. The battery connection can supply enough amperage to light the dome light, the door buzzer, and even the radio. But as soon as you try and engage the starter or headlights, that feeble current path fails and you lose it all. A quick fix is to twist the connectors on the posts, by hand or with pliers, but a proper cleaning is best.

The headlights on most garden tractors don't run off the battery, but from a separate 'lighting coil' that only works when the engine is running. The headlights are controlled through the ignition switch (Off- On- On with lights- Start), probably because one switch costs less than two.

[Tony Ennis]

Ok, I just got in. Mr. Volt-ohm-meter says that battery is at 12.8v. The positive side of the battery looked wet but it wasn't water or acid. Looked oily. I don't know why. I removed the battery and cleaned the lead contacts, then cleaned the wire contacts. I got nothing when I turned the key. I then put on a pair of gloves (bwaak! BWAAAK!) and using my worst set of pliers, crossed the starter contacts per Willy. There was a spark and the engine bumped. Of course I did not do it the second time for fear of damaging something... like me.

So I would think the ignition switch is kaput.

Is this logical enough to warrant buying a switch, or is there something more?