1998 Toro 520xi with 20HP Kohler will not start

[eibbed 62]

Gentlemen,

Well, my neighbor came over again this evening and we have a few more questions that we could use your help with, and some findings that we would like to share with you.

1. Per your instructions, my neighbor checked the diodes and they are working properly.

2. In run; should we have 12VDC at the fuel solenoid, or does that come from the alternator?

3. With the fuel solenoid jumped to the battery the engine runs. This is with the fuel solenoid disconnected from the wiring harness.

4. The fuel solenoid wiring harness has 20VDC when the engine is running and disconnected from the fuel solenoid.

5. One more thing I wanted to share with you is; last summer, while mowing the lawn, after cutting for awhile if I would stop, the PTO would not engage again until after I would let the mower sit for awhile.

We appreciate the help and look forward to hearing from you.

Dave

[doc724 924]

The fact that the solenoid works when you apply 12V directly tells me there is a wiring problem somewhere.  The solenoid is energized in both the start and run conditions (that is why there are two diodes, one lets current flow in the start mode and the other lets current flow in the run mode).  Pull the connector from the ignition switch and pull the start relay.  With your DMM on resistance mode, check the values from the connector to the start relay and then from the relays to the solenoid (make sure you trace to the correct terminal on the relay).  To the relay coil terminal, there should be zero resistance (full continuity).  From the relay contacts to the solenoid there should be 120 ohms (the diode forward bias resistance).  Check the resistance in both the "start" and "run" mode terminals from the connector.  While you have the conncector off, might as well check the resistance thru the start switch.  Check the coil resistance in the start relay (I don't know what is should be).  Now warm up the relay (with a heat gun or hair dryer).  Get it nice and hot and check resistance again.  Remember, for the start circuit to work, there must be a complete circuit thru the relay coil and the relay contacts.  High resistance will look like an open circuit

The fact that you had a PTO problem last summer may indicate and intermittent open circuit with the coil of one of the relays that does not show up when it is cold.  There are three relays (all are identical).  My problem was similar, no start when it was hot.  I moved all the relays around and the problem (so far) seems to have gone away for me.  I don't think it really has gone away, I may have also had a bad relay and by dumb luck, it is now not in the start or PTO circuit (I have not looked at where all three relays are connected)

Take heart, I think you are almost there!

[Rick_in_CT 156]

Dave,

To answer your question #2 above, in the run mode, even with the engine off, but key switch in the run mode, you should have 12V at the fuel solenoid.  If you don't, let us know.  If we can find a missing voltage it will be easier to troubleshoot.  With the wire connected to the solenoid, measure with the red probe on the wire where it connects to the fuel solenoid, and the black prove to a good ground.  Do you have +12VDC??  Next perform the same test, but read the voltage at the fuel solenoid while cranking the engine.  Do you have +12VDC?

Your #3 above pretty much proves that we have a voltage problem at the solenoid.  When you provide a new source of 12V the engine runs.

Your #4 does not make sense to me at this point.  The tractor is 12V, so we shouldn't see anything like 20V.  Possibly this was an anomaly of the meter or a poor ground.

Just in case your neighbor has not seen it, attached is the operator manual for the tractor, with a wiring diagram on page 40/41.  The fuel solenoid is shown in the bottom right corner of page 41.

I know you said that you replaced the battery and cleaned the connections.  I would also check the ground connection at the other end of the battery cable that goes to the negative terminal on the battery.  This should be a connection to the tractor frame and or the engine, I don't recall which.  Also look for a ground coming from the engine to the frame.  If you find one, make sure the connections are clean and tight at both ends.

As Don said, it looks like you are very close.

522xi operator manual.pdf

[eibbed 62]

Hi Rick,

Tuesday night my neighbor read your reply and asked me to respond to your first paragraph with the following;

With the key switch in the run mode even with the engine off, no I do not have 12V at the fuel solenoid.

Performing the same test, while cranking the engine, yes I do have 12VDC.

My neighbor was hinting about me getting a new switch, so I ordered a new OEM which should be here this Friday. I hope it solves the problem.

My #4 reading of 20V was a surprise to us too. We even checked it twice and still got the 20V reading. It is a mystery to us.

I downloaded the manual you provided. It is the same as the one we have been working from, but much easier to look at on the computer. Thanks.

This week I will check the ground connections you suggested.

Thanks again to you and Don and everyone else.

Dave

Wheelhorse TORO start issues.wps

[Rick_in_CT 156]

Looking at the wiring diagram, you can check for 12V at fuse F2 (25 amp fuse) with the key in the run position.  12V should come and go at F2 when you turn the key switch from off to run and back.  If you have 12V there, and not at the fuel solenoid, there is either a break in the violet wire, or the pesky diode is open, and not letting any current reach the solenoid.  If you do have power at F2, then I would skin back a little of the insulation on the wire in front of the diode (opposite side of the diode from the solenoid), and take a DC reading from the wire to ground with the key in the run position.  You should have 12V here in the run position.  If you do have 12V in front of the diode, you should also have it on the other side of the diode.  If the 12V does not get through the diode, then it is bad and needs to be replaced.  Keep checking, you bound to find it soon.

Rick

[Save Old Iron 1,563]

if you have an incandescent test light (not LED), substitute the test lamp for the solenoid and check the lamp lights with the engine and ignition switch in the RUN position.

diodes can sometimes check reasonably well in the ohms position on the multimeter but fail under actual use.

a test light subb'd for the solenoid will check for this condition.

I will be interested in where 20 volts came from in a 12 volt system.
 

Edited May 22, 2015 by Save Old Iron

[eibbed 62]

Praise the Lord!
My new switch arrived today, and it started the engine right up.  I have learned a lot, and can't thank you all enough for your help.
 
I spent about an hour mowing the lawn this afternoon and shut off the engine and PTO.  I immediately started the engine back up and tried to engage the PTO; it would not engage.  Then after it had cooled down, I started the engine up and the PTO engaged.

doc 724 said my PTO problem may indicate an intermittent open circuit with one of the relays that does not show up when it is cold.
  I think I will purchase and install three new relays and see what happens.

I have to go take a shower now; I have grass clippings all over me.  Yes!!!

Dave

[Rick_in_CT 156]

Dave,

Great news. 

Concerning the PTO, looking at the schematic, I don't see the relays as a source of the problem, even if they are heat soaked.  Maybe Save Old Iron can review and comment.   When you restarted the engine "hot", all three relays come into play to make this happen, and by starting it tells me that they are working.  The PTO is controlled by the switch on the dash.  The switch has two power outputs, one goes to the light on the dash that says the PTO is "on", and the other goes to the PTO clutch.  When the engine is hot and the PTO will not work, does the light for the PTO on the dash come on? 

High resistance on the ground wire at the clutch when hot could cause this problem.  Disconnect the connector from the clutch and take a good look at the contacts in each of the plugs.  If heavily corroded they will need to be cleaned.  Many times plugging and unplugging the connector five or six times will scrape the crud off the contacts and improve the connection.  Take a look at the black wire on the tractor side of the harness that goes to the PTO.  Does this wire go to a ground nearby on the engine or frame?  If it does, disconnect the wire and clean the connection up real good, and reinstall.

I would disconnect the wires from the PTO switch one at a time, check the connections for corrosion, clean as needed, and plug and unplug the connection five or six times.

The above steps are the most basic for this type of problem.  Below are the steps to test the PTO coil from the service manual.  You could test it cold, and test it hot, and see if there is any significant change.  The clutch is costly, so hopefully it is just a dirty connection. 

ELECTRIC CLUTCH TROUBLESHOOTING

General Information

Equipment Needed: Volt/Ohm and Ampmeter

The following troubleshooting steps will help

you determine if the clutch has failed or is the

cause of the electrical problem.

Coil Resistance Measurement

Equipment: Volt/Ohmmeter

1. Disengage the PTO, set the parking brake,

turn the ignition key to OFF, and remove the

key.

2. Disconnect the clutch wire connector.

3. Set the volt/ohmmeter to check resistance

(ohms).

4. Connect the meter lead wires to the wires in

the clutch connector.

The meter should read between 2.40 and

3.40 ohms. If the readings are not within

specifications, the coil has failed and the

clutch must be replaced.

If the resistance is within specifications, the

electric clutch is not the source of the

problem.

SAFETY INTERLOCK SYSTEM

Purpose

The safety interlock system is designed to

prevent the engine from starting unless:

1. You are sitting on the seat.

2. The brake pedal is depressed.

3. The power take off (PTO) is OFF.

The system will also kill the engine if you

attempt to operate the clutch or drive system

when you are not in the seat.

Testing

1. Set the parking brake. Move the PTO to ON.

Now turn the ignition key to START; the

engine should not crank.

2. Push the PTO to OFF and release the

parking brake. Now turn the ignition to

START; the engine should not crank.

3. Set the parking brake and move the PTO to

OFF. Start the engine. While the engine is

running, release the parking brake and rise

from the seat; the engine should stop.

[eibbed 62]

Hi Guys,

I wanted to drop a line to let you know what has or should I say has not been happening.

My neighbor has been pretty busy and unable to take time to bring his OHM Meter over and check the PTO wiring.  I am sure he will be over when he can.  Fortunately I can still mow the lawn with it like it is. 
 
Rick to answer your first paragraph in your last reply; after the last time I finished mowing the lawn, the PTO would not engage, but the PTO light on the dash did come on.

So far I have been unsuccessful in unplugging the clutch wiring connector from the PTO  switch.  There is not enough room for my hand.  I will try to come up with a plan B.  Maybe I can use a screw driver to carefully separate the two.

I'll  get back to you all as soon as I know something.

Take care,
Dave 

       

Edited June 11, 2015 by eibbed

[shallowwatersailor 3,213]

Try removing the left intake screen. That should possibly give you some additional room.

Edited June 11, 2015 by shallowwatersailor

[eibbed 62]

shallowwatersailor,
Thanks for the suggestion, but removal of the intake screen won't give me any additional room to work. 
How can I check out the 5xi Club?
Dave

 

Edited June 14, 2015 by eibbed

[eibbed 62]

My son-in-law was able to remove the PTO switch today and none of the connections look corroded. 
I ordered a NOS PTO switch anyway,  as a process of elimination.  
Dave