Z930M Mower: Steady Red Warning Light Diagnosis

[Ontheback9!]

All of my usual questions have been answered by reading other people's posts, but not this one. I have a John Deere Zero Turn mower, model Z930M (54" cut). Bought it used but not cheap. Now at 1,200 hours and I use it for a three-acre field and 2-acre lawn. Once I learned how to turn without chewing up turf, I love using it because the tweels give a great cut BUT the ride is just short of a mechanical bull. I maintain with annual maintenance. Red light (steady, not blinking) came on on the left side bottom of the instrument panel near the ignition slot. Not the diagnostic light by the picture of the little wrench on the right bottom. This one is next to what looks like an oil drop. Anyway, I: drained and replaced oil (SAE 20-50 per dealer), replaced oil filter, replaced the dual air filter (inside and outside tubes), checked battery voltage (at 12.3 volts), changed both spark plugs, checked for any loose connections or frayed wiring, including the emergency stop sensor under the seat, and cussed a lot. I've been using the mower anyway and it starts and runs perfectly, like before the light showed up. Online research never covered this warning light. Went to the dealer. Said it was the oil pressure sensor/switch but no one there had ever seen the steady red light before. Easy fix--cleaned up wiring and wire clip, pulled old sensor and put in new one. I'm behind on lube jobs but that wouldn't cause this warning. I have very little mechanical skill but try to hang on. Can anyone diagnose the issue and fix or should I just keep using until it dies or explodes?

 

[StarTech]

From service manual


Yes either oil pressure has failed or the engine operating oil pressure has dropped below 14.2 psi. I have seen both to occur.

Remove the oil pressure switch and install an oil pressure gauge. Note many Kawasaki engines uses a 1/8-28 BSPT (British threading) instead of the the US NPT of 1/8-27 so make you use the correct adapter. [Note many cheap oil pressure gauge sets don't even include the British threaded adapter but offer them as optional fittings.] Test after the engine is fully warmed up. If the oil pressure is indeed low it likely the Gerotor gear set in the oil pump of the engine. IF you keep using the engine with low oil pressure it will fail.

As engine heats it thins the oil to a point that the oil pressure drops below the considered safe operating when this Gerotor is heavily worn. Can start at low rpm and as the gears wears gradually happens at higher rpms.

Even the local JD dealer couldn't diagnose this problem that one of my customer had on a 3000+ hrs Z925A. One tech even told the customer that his engine didn't have an oil pump and to ignore the warning light. Apparently he never lookup the engine IPL or read the service manual. So I have no confidence in the JD service shop. They couldn't find a bad spark plug in a Stihl hedger either.