520-8

[dkg520 509]

I have a 520-8 that was running great til last week.  I turn the key and get no power at all.  New battery installed and I have power to the starter but nothing when I turn the key.  I tried a new ignition switch but get the same result.  Anyone have any ideas on where I should start. Thanks for any help.

[gwest_ca-(File Mod) 11,070]

Download this file. Each circuit has it's own diagram making it easy to follow. They illustrate what it takes to make it work.

 

[Handy Don 12,281]

32 minutes ago, dkg520 said:

Anyone have any ideas on where I should start. Thanks for any help.

I always start with obvious connections--are they clean and tight?

Battery positive and negative?

Ground from battery to engine?

Connections to the ignition switch?

Connections to safety switches?

And, specific to the Onan-powered tractors, any visible damage or overheat evidence at the 9-pin connector that links the engine wiring to the tractor?

 

Then look for broken or frayed wires.

 

I’m not directly familiar with that model, but in your situation, “no life when trying the key”, I’d look for problems at the safety switches--disconnected wires or broken switches, for example. Clutch, seat, and PTO safeties can all affect start/run. Use the wiring guide to look for continuity and voltages as you trace the wires. I’m assuming you have a working volt/ohm meter and know how to use it, of course!

 

Take NOTHING for granted -- I even, sometimes, distrust a new battery until I’ve tested it.

[ri702bill 8,387]

Onan engine with the dreaded 9 pin Connector?? If so, there's a good place to look for apparent issues.....

[Ed Kennell 38,329]

52 minutes ago, dkg520 said:

I have power to the starter

If you have 12v to the starter it should be spinning.    If it is spinning and not engaging the flywheel, you need to clean the bendix.

[lynnmor 7,321]

You will have power at the big wire at the starter, check for power at the small blue wire when you turn the key to start. 

[Handy Don 12,281]

Sorry, this may be plug simple and I missed it.

Is the PTO disengaged? If not, no start!

(No need to ask how I know about this.)

[SylvanLakeWH 25,618]

6 minutes ago, Handy Don said:

Sorry, this may be plug simple and I missed it.

Is the PTO disengaged? If not, no start!

(No need to ask how I know about this.)

 

I've heard that some people may have, uhm, done that... 

[Ed Kennell 38,329]

Just now, SylvanLakeWH said:

 

I've heard that some people may have, uhm, done that... 

   Usually when you run out of fuel while mowing.   Carry fuel out and fill the tank and no start.    

[8ntruck 7,034]

3 hours ago, SylvanLakeWH said:

 

I've heard that some people may have, uhm, done that... 

Nope.  Not me.  Never ever.

[953 nut 55,393]

There is a 25 amp fuse in line from the battery (via the solenoid connection) to the ignition switch. It is near the battery and over the years acid fumes from the battery being charged will cause the fuse holder to begin corroding. This is likely to be the problem, replace it with a HEAVY DUTY 30 amp fuse holder.

[dkg520 509]

Spent all morning checking and tightening all connections but still nothing at all when I turn the key.  Can anyone tell me what this is?  And what it does.  Thanks

[Handy Don 12,281]

Yes. It is a relay.

Apply 12v power across terminals 1 & 2 and it closes the circuit across terminals 3 and 5.

 

From the schematic, it looks like the Start Relay.

If it is:

- the red wire should go to a terminal on the starter motor that also has a wire from the battery

- and a light blue wire should go to a different terminal on the starter motor. 

 

As I read the diagram, a test jumper between the these two would circumvent ALL safety switches and most other wiring and crank the engine (BE SURE THE TRACTOR IS IN NEUTRAL WITH THE PARKING BRAKE SET BEFORE ATTEMPTING THIS). If this works the problem is at or before the relay.

 

With the relay in place, can you jumper 12v from the battery + into the socket where the light blue wire from the clutch pedal enters? This tests the relay by circumventing the fuse, the ignition switch, and the PTO and clutch safety switches. to trigger the relay and cause the tractor to crank. If yes, the relay is good and the problem is before the relay.

 

PTO is disengaged?

Clutch pedal is down?

If you disconnect the relay (remove it from the socket), an attempt to start (with the above conditions met) should get you 12volts in the socket where the light blue wire enters on either terminal 1 or 2 (it’ll be coming from the clutch pedal switch). If not, you know the problem is in the fuse, the ignition switch, or the PTO or clutch pedal safety switches. Work backward looking for the 12v.

 

Let us know what you find.

[dkg520 509]

Where exactly will I find the clutch pedal switch?  Thank you for you help

[Ed Kennell 38,329]

13 minutes ago, dkg520 said:

Where exactly will I find the clutch pedal switch?  Thank you for you help

The inner side of the clutch pedal contacts the switch when the pedal is depressed.

[Handy Don 12,281]

37 minutes ago, dkg520 said:

Where exactly will I find the clutch pedal switch?  Thank you for you help

That I don’t know--not a model I’ve worked on.

 

Not being cheeky, I’d trace that light blue wire that DOESN’t go to the starter. It should lead to the clutch switch which must be near the pedal or linkage so that it can detect when the pedal is depressed.

I assume you have the manual with the IPL (illustrated part list). If not, search in the Files section of this site for “Tractor 1990 520-8 IPL” (set the “use all search terms” option). That’ll help you locate the manual which might help--at least it’ll show you what the switch looks like!

[dkg520 509]

Thank you all

[gwest_ca-(File Mod) 11,070]

I believe the clutch switch is item 60 at the bottom right of this page.

https://www.partstree.com/models/41-20o801-520-8-toro-garden-tractor-1990/electrical-system-11/

I think you will find it between the transmission drive belt idler pully and the center consul. It is on the inside and the top/back of it can be seen if you look through the shifter slots in the panel.

This is based on what other 1990 models used although the 520-8 switch 119440 is different for some reason.