Don't you love intermittent problems?

[Brian Elfert]

Lawnmower didn't crank about a month ago. I left it for about an hour and decided to try again and it cranked just fine and started right up. Fast forward to Monday evening and it was dead again. I tested interlocks and they were good so started pulling fuses to check them. I didn't see any issues with fuses, but when I went to test for voltage at the solenoid it started right up when key was turned. Wiggled all kinds of wires and it still started a number of times. I was prepared to trace through the wiring diagram to figure it out.

Don't you just love intermittent problems like these? I don't know if reseating the fuses fixed it, or just coincidence. (Fuses were nice and clean with no corrosion on fuses or holders.)

[Rick Potter]

Is this where we are supposed to answer......' Of course I have intermittent problems, I'm married'.

Just thought I would be the first ;).

[Dave Anderson NH]

But you won't be the last Rick.:D

[Jim Becker]

Brian, ironically, I've been having a similar issue with my SCAG ZTR...it's back in the shop waiting on a voltage regulator to arrive from Briggs and Stratton "as we speak". New battery about three weeks ago and some other parts and adjustments, but still no joy in maintaining a charge. They dug deeper this time and determined that additional parts needed replaced. Not great timing for me as our other property is for sale and I've been trying to keep things really neat and tidy. I may have to mow it twice this coming week when the machine is fixed to get it back to the normal 4" height! I've learned to keep an emergency battery pack with me in recent months for this!

[Lee Schierer]

It is probably one of the interlock switches with a dirty contact. Next time it won't start try actuating one switch at a time then attempt to start the lawn mower. The last switch you touched will be the problem.

[Kev Williams]

A few years ago I had the exact same intermittent problem with starting our Chaparral. It turned out to be the solenoid :)
-It was a bit obvious what was wrong once the starter was removed-
460936 ;)

BUT I've had several solenoid issues over the years, pretty much to the point where IF a solenoid is any part of an intermittent or general electrical failure, I just change it. :)

[John K Jordan]

...
Don't you just love intermittent problems like these? I don't know if reseating the fuses fixed it, or just coincidence. (Fuses were nice and clean with no corrosion on fuses or holders.)

For electrical problems on things that are exposed to humidity (cars, farm equipment, trailers, light sockets, extension cords, circuit breakers in outdoor or sheds/barn/garage, etc) I clean and put a smear of dielectric on all contacts. This helps to keep the air and moisture away. It really works.

Clean with electrical contact cleaner and fine scotchbrite or 800 grit sandpaper if needed. Dielectric grease is available at auto parts and electrical supply stores, most hardware stores. Rather than the tiny squeeze tubes I buy in dispensers similar to this one: https://smile.amazon.com/CRC-6113-Marine-Dielectric-Grease/dp/B0788Y4SN8

[Brian Elfert]

It is probably one of the interlock switches with a dirty contact. Next time it won't start try actuating one switch at a time then attempt to start the lawn mower. The last switch you touched will be the problem.

I thought an interlock switch might be bad, but the switches were all showing continuity and it still wasn't starting. The problem went away after removing and reinserting three fuses in the back near the starter. The fuses were fine with no corrosion and they fit very tight in the holders. It may have just been coincidence with the fuses.

I talked to the support line at the manufacturer and the tech said the neutral safety switches are usually what go bad in the interlock system. I will probably spend the $25 to replace both switches if the issue comes back. (Support line is supposed to be dealer only, but they still helped me. I actually called initially because I had it to the dealer twice for a different issue.)

[Brian Elfert]

It turns out that this mower was used pretty hard by the previous owner. I had to pull the fenders off to get at the interlock switches. There was all kinds of mud and grass under the fenders. I opened up the dash panel and it was full of mud and grass inside. I washed everything and let it dry for half a day before putting it back together.

The selling dealer cleaned the outside up so it looked real nice, but obviously they were not going to pull parts off to deep clean.

[Jim Koepke]

I thought an interlock switch might be bad, but the switches were all showing continuity and it still wasn't starting.

In my experience switches can show continuity with a meter but not under load. Clip the meter, reading voltage, across the switch and try starting. A good switch will show close to zero volts. A switch with burnt or dirty contacts may read up to full system voltage.

jtk