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.

 

[Auto Doc's]

Many modern dealer techs are just there for a paycheck and waiting until and easier job comes along that does not require them to think. LOL

This thing needs an oil pressure test with a gauge before the engine decides to possibly come apart. These have an oil pump system that pumps oil to the bearings inside the engine.

If it reads good oil pressure above 14.2 PSIG at idle, then the problem is in the wiring or possibly the ignition switch.

 

[StarTech]

The ignition switch has nothing to do with the oil pressure other powering the instrument cluster. Turning off engine and starting it.

 

[Auto Doc's]

The ignition switch has nothing to do with the oil pressure other powering the instrument cluster. Turning off engine and starting it.
View attachment 71645

I notice the oil light has a diode, maybe it is open? Does the light stay on with the sensor connected or disconnected both while running?

 

[StarTech]

That is a LED (light emitting diode) hence the light emitting arrows. If it was open or shorted there would be no light up. Now there could be a short in the 620 Tan wire rubbing or mice damage. And I have seen the wire to be bare at the pressure switch that could touch ground.

But we need the OP chime on what he or she has checked.

Also as info LCD is a Liquid Crystal Display.

 

[Auto Doc's]

Thanks for the refresher on the symbol. That leaves the 620 Tan wire or there is a loss of oil pressure. Maybe we will hear something back from the OP.