No spark

[2005 0]

now at + side of coil two wires on this post

the red from sensor and a black that puts 12 volts to coil comes from 6 pin harness

...i have 12 volts on plus post at coil with key on run

so far so good but what about the condenser connection ? It should also be on the (+) terminal of the coil.

then when i touch red lead from sensor it goes to .54 volts?????

this is where you lose me - what do you mean by "when i touch red lead" apparently you are using a voltmeter - are you touching the positive lead of the voltmeter to the positive lead of the coil ? If so, the (+) lead of the coil should always remain at battery voltage. The negative (-) terminal of the coil is the only terminal that transitions from 12 volts to near ground (1volt or so).

also on - side 12 volts but when crankin drops to half to one volt...this is good for -side

now two black wires on neg. post 1st blk wire comes from sensor..

2nd is small diode silver with one blk lead goes to neg .post is my wires correct????

2nd wire on the negative terminal ?? That may be your problem, The "silver diode" as you call it may be the condenser and if so, it should be hooked up to the positive (+) coil terminal

so correct configuration would be

3 wires on the positive (+) coil terminal

and

1 wire on the negative (-) coil terminal.

I will check back later this evening to see how things are progressing with the fix.

o.k. news flash!! i ran a jumper from pos. battery post to pos coil post and whalah!!! tracter fired right up:):)ssooo now what did i bypass and does it need replaced????

[2005 0]

now at + side of coil two wires on this post

the red from sensor and a black that puts 12 volts to coil comes from 6 pin harness

...i have 12 volts on plus post at coil with key on run

so far so good but what about the condenser connection ? It should also be on the (+) terminal of the coil.

then when i touch red lead from sensor it goes to .54 volts?????

this is where you lose me - what do you mean by "when i touch red lead" apparently you are using a voltmeter - are you touching the positive lead of the voltmeter to the positive lead of the coil ? If so, the (+) lead of the coil should always remain at battery voltage. The negative (-) terminal of the coil is the only terminal that transitions from 12 volts to near ground (1volt or so).

also on - side 12 volts but when crankin drops to half to one volt...this is good for -side

now two black wires on neg. post 1st blk wire comes from sensor..

2nd is small diode silver with one blk lead goes to neg .post is my wires correct????

2nd wire on the negative terminal ?? That may be your problem, The "silver diode" as you call it may be the condenser and if so, it should be hooked up to the positive (+) coil terminal

so correct configuration would be

3 wires on the positive (+) coil terminal

and

1 wire on the negative (-) coil terminal.

I will check back later this evening to see how things are progressing with the fix.

o.k. news flash!! i ran a jumper from pos. battery post to pos coil post and whalah!!! tracter fired right up:):)ssooo now what did i bypass and does it need replaced????

could it be the voltage regulator?????

[hckypck7 1]

I think if it starts when u have a jumper from + post to + post on coil its the low oil pressure sensor. That's what I read in manual.

[2005 0]

I think if it starts when u have a jumper from + post to + post on coil its the low oil pressure sensor. That's what I read in manual.

oh cool!! i have no manual...so thats what wheelhorse is sayin???? so that would mean flywheel comes off again!! how is your project commin along?????

[hckypck7 1]

I have traced it down to ignition control module.

I am glad I found the forum cause they helped me a lot. I found a place to get the sensor but it cost 200.00, someone posted on here to go to onanparts.com and they have it for 80.00. Saved me a lot of money.

Now I am waiting impatiently for part to get here.

[hckypck7 1]

U can download the manual for Onan off this site. That is where I got it. Helped me out a lot also.

[2005 0]

I have traced it down to ignition control module.

I am glad I found the forum cause they helped me a lot. I found a place to get the sensor but it cost 200.00, someone posted on here to go to onanparts.com and they have it for 80.00. Saved me a lot of money.

Now I am waiting impatiently for part to get here.

yep...that was my post...glad it saved you $$$$$... i was just at their site to find low oil pressure switch...$24.00..not bad

U can download the manual for Onan off this site. That is where I got it. Helped me out a lot also.

thanks !!! download successful..now i have it....

[Save Old Iron 1,564]

I'll have to check again, but an oil LEVEL switch prevents CRANKING if the oil level is low. An oil PRESSURE switch will usually just trigger an indicator light on the 520 dash and keep the hour meter from clocking off run time.

What year 520 are we working with here?

Wiring the (+) battery to the (+) ignition coil bypasses connectors, fuse holders and safety switches. Not sure the oil switch is the next best step to take.

Great job so far with rewiring the ignition coil - glad that worked out without damaging any parts you already replaced. One warning to be aware of is

NEVER - EVER jump the (+) battery to the negative (-) lead of the ignition control module.

This will short circuit current thru the ignition control module and overheat and destroy the module instantly.

As an FYI. I pulled out several ignition modules I have laying around and came up with a way to check them out before inserting them into the tractor. More to come,

[Save Old Iron 1,564]

Lincman

how you doing ?

[lincman 3]

I got mine running, just an issue with the igintion switch. Some dirty contacts and a that haunting carb issue I dealt with back in Febuary. Such a tempermental ol' tractor. Thanks for all of the info everybody.

[2005 0]

I'll have to check again, but an oil LEVEL switch prevents CRANKING if the oil level is low. An oil PRESSURE switch will usually just trigger an indicator light on the 520 dash and keep the hour meter from clocking off run time.

What year 520 are we working with here?

Wiring the (+) battery to the (+) ignition coil bypasses connectors, fuse holders and safety switches. Not sure the oil switch is the next best step to take.

Great job so far with rewiring the ignition coil - glad that worked out without damaging any parts you already replaced. One warning to be aware of is

NEVER - EVER jump the (+) battery to the negative (-) lead of the ignition control module.

This will short circuit current thru the ignition control module and overheat and destroy the module instantly.

As an FYI. I pulled out several ignition modules I have laying around and came up with a way to check them out before inserting them into the tractor. More to come,

thanks for coil wireing diagram!! helped alot...but mine is a p218...so maybe stir away from oil pressure switch....maybe voltage regulator???? what do you think???

[Save Old Iron 1,564]

lincman - great news - thanks for the update.

[Save Old Iron 1,564]

2005,

the voltage regulator is part of the charge circuit and will only affect the ignition circuit if the battery is not charged enough to provide sufficient power to the ignition circuit. A quick check of the regulator is to run the tractor at 3/4 or higher throttle. If the battery voltage is at 13.8 or higher, the regulator is OK.

the pressure switch will not prevent ignition - think about it - as the tractor is in its first few seconds of cranking, the oil pressure is non existent - the ignition circuit still has to be enabled even if the oil pressure is at 0 psi. A quick check is to note if the oil pressure light is flashing on the dash when the engine is not running but the ignition switch is in run. If the oil light turns off when the engine is running, the oil pressure switch is OK.

the area you might benefit from investigating is the wiring supplying power to the ignition coil. If you have the demystification guide, locate the PTO switches and the neutral safety switch. A test light would be useful to trace where the power to the ignition coil is interrupted. I'll be around to help with any questions.

[2005 0]

2005,

the voltage regulator is part of the charge circuit and will only affect the ignition circuit if the battery is not charged enough to provide sufficient power to the ignition circuit. A quick check of the regulator is to run the tractor at 3/4 or higher throttle. If the battery voltage is at 13.8 or higher, the regulator is OK.

the pressure switch will not prevent ignition - think about it - as the tractor is in its first few seconds of cranking, the oil pressure is non existent - the ignition circuit still has to be enabled even if the oil pressure is at 0 psi. A quick check is to note if the oil pressure light is flashing on the dash when the engine is not running but the ignition switch is in run. If the oil light turns off when the engine is running, the oil pressure switch is OK.

the area you might benefit from investigating is the wiring supplying power to the ignition coil. If you have the demystification guide, locate the PTO switches and the neutral safety switch. A test light would be useful to trace where the power to the ignition coil is interrupted. I'll be around to help with any questions.

i think im with you on the wiring prob. that will be next area that i explore..also like you were sayin..maybe a saftey switch may be coroded???? i will let you know how i make out...you've been a great help so far...thanks!!!!

[hckypck7 1]

Ok update. I purchased a ignition control module and put it in and it started right up. ran it for a half hour on and off a couple of times just checking to make sure everything was ok. Shut it down to clean grass off with air compressor and now it won't start. The dash lights come on but it doesn't turn over. I replaced the neutral safety switch already . So now I am guessing one of the other switches is bad. The question I have is can u bypass these switches and if u can how do u do it? Or if anyone has any other ideas where I can look to get it started again, I would greatly appreciate the help.

[2005 0]

Ok update. I purchased a ignition control module and put it in and it started right up. ran it for a half hour on and off a couple of times just checking to make sure everything was ok. Shut it down to clean grass off with air compressor and now it won't start. The dash lights come on but it doesn't turn over. I replaced the neutral safety switch already . So now I am guessing one of the other switches is bad. The question I have is can u bypass these switches and if u can how do u do it? Or if anyone has any other ideas where I can look to get it started again, I would greatly appreciate the help.

my 18 horse has a 20 amp fuse down beside the starter ....maybe???

[hckypck7 1]

I checked fuses and they r all good. The 520 has the fuses on top by battery. There are three of them. I checked manual to see if there are any by starter. I didn't see any other then the three by battery. Thank you for the help.

[Save Old Iron 1,564]

hckypck7,

the issue with 520's and fuse holders has always been degredation and corrosion INSIDE the fuse holder. Posts have all centered around corrosion of the holder, and heat developing inside the holder. Remove the fuses and check for clean contacts in the holder.

[2005 0]

2005,

the voltage regulator is part of the charge circuit and will only affect the ignition circuit if the battery is not charged enough to provide sufficient power to the ignition circuit. A quick check of the regulator is to run the tractor at 3/4 or higher throttle. If the battery voltage is at 13.8 or higher, the regulator is OK.

the pressure switch will not prevent ignition - think about it - as the tractor is in its first few seconds of cranking, the oil pressure is non existent - the ignition circuit still has to be enabled even if the oil pressure is at 0 psi. A quick check is to note if the oil pressure light is flashing on the dash when the engine is not running but the ignition switch is in run. If the oil light turns off when the engine is running, the oil pressure switch is OK.

the area you might benefit from investigating is the wiring supplying power to the ignition coil. If you have the demystification guide, locate the PTO switches and the neutral safety switch. A test light would be useful to trace where the power to the ignition coil is interrupted. I'll be around to help with any questions.

i think im with you on the wiring prob. that will be next area that i explore..also like you were sayin..maybe a saftey switch may be coroded???? i will let you know how i make out...you've been a great help so far...thanks!!!!

o.k. update to "save old iron" got home tonite after work and hit the wheelhorse great news it is runnin!!!!!! thank you sooo much for all your input and you were absolutly correct with it being the wiring had to change 3 spade connections and cleaned 2 fuse holders and cleaned the saftey neutral switch and bam it started right up......now wonderin if all the new parts were really what she needed????? old coil and ignition control..conensor and key switch may be good after all?????? but hey thanks again bud!!!!!!! couldnt have done it with-out ya!!!

[Save Old Iron 1,564]

......now wonderin if all the new parts were really what she needed????? old coil and ignition control..conensor and key switch may be good after all?????? but hey thanks again bud!!!!!!! couldnt have done it with-out ya!!!

That's always great news to hear - Hurray - another happy Onan - Music to the ears.

And now the question of "were all - or any - of these parts necessary". Precisely why I always try to promote TROUBLESHOOTING to solve a problem instead of GUESSING at a fix. Guessing a "form" of troubleshooting but I really dislike spending other people's money guessing a problem away.

Hang on to the parts you have. I have been investigating how to check the ignition modules without actually placing them in an engine. I should have something bread-boarded soon enough. I have a few modules laying around and would like to be able to tell if they are functional without mounting them in a test engine.

[Save Old Iron 1,564]

Ok update. I purchased a ignition control module and put it in and it started right up. ran it for a half hour on and off a couple of times just checking to make sure everything was ok. Shut it down to clean grass off with air compressor and now it won't start. The dash lights come on but it doesn't turn over. I replaced the neutral safety switch already . So now I am guessing one of the other switches is bad. The question I have is can u bypass these switches and if u can how do u do it? Or if anyone has any other ideas where I can look to get it started again, I would greatly appreciate the help.

I have not forgotten about you sir, let me put together a few places to check for a no crank issue on the 520.

Before we get too involved in dis-assembly to check wiring, it is possible the dash lights might be pointing us to the culprit?

Do you have any dash lights on that would indicate a problem with the seat. PTO or motion lever neutral switches?

Going back to your earlier posts, it seems when you replaced the safety switches, you had success in cranking the engine. We may have to consider the switches to be functional but maybe the push on terminals to the switches are corroded. This condition would cause intermittent contact with the safety switches.

[hckypck7 1]

Got it running again. I guess it was a bad ground. Now running like a top. Now to get Hood and steering wheel.

Thanks for everyone's help. If I need any info again I will post again. You guys have help out a lot.