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Mower Problems "Hana Side"


Most all riding mowers in the Hana area experience problems not normally experienced in a flat dry area. The mowers I am including in this problem page are the riding mowers made by John Deere, Craftsman and others mowers that were sold at Lowes or Home Depot and so on as the "homeowner" riding mower and in the priceline of $1,500.00 to $2,500.00.

 

From the littlest item to the largest, in reference to cost and work involved for repairs, or preventative maintenance. The  work performed on a daily basis at home has to do with taking some time to save money and expences later for breakdown repairs. The PM (preventive maintenance) is done prior to the machine breaking out in the field and the check list for each machine is close to the same. A gas engine, a diesel engine, a propane engine are all about the same in the fact that they need oil for reducing friction and part cooling properties. Some use water to cool the engine and some use air and no radiator.

 

 

So the PM would include check the engine oil level and note on a page exactly how much oil you added. This way you can tell how much oil you added and write down the engine hours. The hotter an engine runs the more oil it consumes. So a person putting on 10 hours with the throttle wide open on a flat lawn a couple inches tall consumes less oil than a person mowing 10 hours with the throttle wide open going uphill mowing grass 1 foot tall. So engine hours are not a definitive indication of when to do your PM, that should be done each time you operate the mower. Just simply cleaning the grass from the cylinder cooling fins when air cooled and cleaning the radiator outside that has grass buildup as mowing with a water cooled engine.

 

 

The top of the engine usually always has a plastic or metal on the end that spins as the engine is running. This is the piece that blocks small grass from going into the cooling fins of an air cooled engine. If this piece is not there or has large holes in it you need to replace it or cost yourself further problems and more money by overheating the engine by preventing the air to flow over the cooling fins of the cylinders and cylinder heads of the engine from grass stuck in the fins of the air cooled engine.

 

 

Electrical is the biggest failure due to wet environment in the Hana area. Not only is it wet but the salt air rots metal quicker than if it were a dry hot enviroment. After setting for awhile the solenoid that makes the starter work get's stuck and then no start. Holding the keyswitch on start and tapping on the solenoid with something ligh and made of wood usually makes them work again until the mower sets for a couple weeks.

 

Leaving a PTO switch on in an electric pto circuit will disable the starting system with no clicking noise of the starter solenoid as the switch is turned to start. Most riding mowers need the safety functions for the mainland legal liability requirements as well as the Good Manufacturing Policies as the guideline to a sellable product that has high liabilities attached.

 

The safety circuits usually always begin with a switch to close and supply a potential voltage to the next switch and so on, this is called a seriesed circuit when one switch output connects to the next switch input. So the series starts at the ignition key switch and when closed directs voltage to a wire and on a John Deere it is usually always the purple wire from the ignition (key) switch. It then goes through a system of relays controlling the ability of the relay system to conduct current into the coil electromagnet within the starter solenoid. Actually it's simply and electromagnetic solenoid but in this application it supplies current capabilities for the starter motor. In the field the first thing to do is touch a wire to the battery + and the other end to the purple wire spade terminal of the John Deere starter solenoid coil. This bypasses everything and all the safety circuits so "if" the starter solenoid does not rotate the engine or no click is heard or spark at the wire end you are touching to the solenoid coil then replace the starter solenoid.

 

"If" the solenoid clicks as the wire is touched to the terminal but the starter does not rotate take a battery jumper cable end and clamp it on the two large terminals of the solenoid coil, there will be sparks but not to worry sparks mean the starter is getting power to rotate. If the engine starts to rotate by connecting the jumper cable end to the solenoid large terminals then replace the starter solenoid, they are usually around 20 bucks.

 

 

After you have made the starter work the engine will start even if the key is not on because the mower engine gets it's spark to run as the flywheel is rotated, it is not like your car engine electrical. What shuts the engine electrical off is the grounding circuit, the ignition coil has the spark plug wire attached to the spark plug and there are no other wires needed on the coil for the system to produce spark to run the engine. The magnets inside the rotating flywheel pass by the coil and produce spark. The only way to stop that without pulling the spark plug wire out or stopping the rotation of the flywheel is to put the coil to ground on both wires going into the coil. In the coil there is one wire with two ends, one goes to a ground and the other goes to the spark plug and to ground of the engine. On the outside of the coil there is one terminal and when this terminal is grounded to the metal framework of the engine the spark stops at the plug.

 

 

When the key switch is opened the starter relay system closes the circuit to ground going to this coil wire. The engine will start even with the key off if this ground wire is unhooked from the coil.

 

 

Once you establish that the starting system actually works then you can go onto finding your starting problem that may end up as a loose terminal end on some safety switch. There is a brake switch that closes when the brake is on and the operator does not need to be on the seat for the starting system to work and the first thing to test is by placing the park brake in the lock position and then try to start the engine on the mower. If the engine starts let it run and then take off the brake and make sure it stops running as soon as the brake is released and you are not on the operators seat.

 

Important is the fact that a loose seat cushion or a rotted out seat switch will cause the mower to cut out while mowing like a glitch. The following picture is for identifying the safety and starting circuit.

The diagram to the left is to example a generic layout of electrical switches found in most all riding lawn mowers.


20 is the voltmeter connected to the battery as the switch 24 is closed.


The #24 switch is closed by rotating the key 23 clockwise. This allows voltage to go from the battery to the volt meter and to the ignition switch through the electrical wiring cable 8.

 

Through the cable 8 the electricity travels to the switches. The first switch inline to test is the pto switch #7 and if the pto switch is closed electricity continues to the brake switch 17. When the brake switch is closed or brake locked in park wire 13 can then be energized electrically through the breaker relay 14 from the keyswitch closing in the start position and at starter solenoid 11.

In the schematical diagram below is a more modern circuit with an electric pto circuit. In general most all equipment has to have this electrical safety switch and circuit.

The components on the page above are switches, relays, terminals, and a meter. The switches are to allow electricity through by making (closing), or to break (open) the circuit so no electricity can go through. These switches in the order they allow electricity to pass are; Ignition Switch 8 to power circuits and safety switches. The safety switches simply open the circuits of priority so no voltage can go to start the engine. The voltage is applied to the small wires on the coil terminals, the larger cables are attached to the battery and are live all the time and the other cable powers the starter motor after one of the wires on the coil to the solenoid gets voltage.


The starting of your mower is most likely the reason you are reading this, when there is no clicking noise as the key #9 is rotated clockwise to the start position, most likely the starter solenoid (relay) is not free to slide the switch in to the contacts inside the solenoid switch. Tap lightly on the solenoid as the keyswitch is turned to the start position and hold it there while tapping on the solenoid body. If the center switch plunger piston is a little coroded which happens quite a few times here it will break free and start the engine. If not then go to the next switches inline.

 

The next switch happens to be the testpoint at 36 Left Terminal, if that has voltage it will turn on your mower dash and headlights by rotating the starter switch 8 with key 9 to run position. This is due to the terminal 36L has the battery cable attached and if the battery is good it will light the dash and lights up when the ignition switch is rotated to run (first detented position). If the headlights turn on and seem bright try to rotate the ignition switch to start as the brake locked in the park position.

 

If the starter does not rotate the engine and the lights do not go dim as the ignition switch is closed then there is no voltage going to the starter solenoid + wire. The starter solenoid coil terminal leads in this application are located on the top edge 35 of starter solenoid 11B. These terminals are two male spade terminals and they have the two smaller wires attached to them. One wire simply goes from a coil terminal to ground and the other one is + and usually always purple on the John Deere mowers. Most all mowers with the exception of Honda use black as the ground an on most all Honda motorcycles the green is ground and white is hot + from the battery. I usually just look at the wires and where they go. One small one will go directly back to a bolt on the mower frame ground and the other will go back to the keyswitch, that is the hot + battery lead.

 

Once you establish the battery is good by turning on the headlights or using a volt meter then you can begin your search for the problem of no start. I use the old bright light method where you simply turn on the circuit at the switch turn on the headlights and try start the engine. If the lights stay on and there is no difference in brightness as the starter switch is rotated to start then there is nothing being taken out of the battery meaning we have a mower that will not start and the headlights turn on as the switch is closed. If nothing goes on there is a main fuse to check and if nothing happens and the fuse is good disconnect the battery cables and clean the terminal ends and bend them slightly. If they are hard to bend and make a cracking noise inside the cable as you bend them then replace the cables, they are core eroded and it migrates like a cancer in a wire.

 

Once the battery is established as good and the cables have been removed, cleaned and inspected and the fuse has been removed and cleaned and put back in then you are ready for the safety circuit. The pto switch #31 usually has multiple terminal connections but the important part here is the purple wire from the ignition switch or + supply as the keyswitch is rotated to start. I usually use an old headlight to check voltages on the electrical systems. This is due to a meter is highly sensitive to fractions of a volt, you can measure 12 volts with the meter but if a connection is coroded you still get the reading but when something is connected like the starter solenoid coil it does not have the ability to carry the current so the device does not operate even "if" the voltmeter shows good voltages. My advice if you have no meter is to get an old headlight like the one in the mower and connect two wires to it, a light is a single conductor so it does not matter which is + or - it does not matter it just takes two wires.

 

So put one wire end in the - terminal or on the ground to the machine the other end from the other wire going to your headlight tester and touch wires and find which ones light up the light. You can get close to guessing the voltage by the brightness of the light. The brightness of a single conductor light is in direct porportion to the applied voltage. If the light is bright it is right, light dim things are slim. Go to the switch and rotate it to the start position, find the wire going to the pto switch 31.

If you have a digital volt ohm meter and your mower John Deere mower will not start and you have an electric pto below is a complete step by step instruction on how to test the starting and pto circuit. The below PDF link is for the more advanced mechanic or electrical test person and shows electrical schematics as well as color code of John Deere mower wiring. Since this a safety circuit it is what prevents the mower from starting.