No spark

[hckypck7 1]

I have a '96 520H wheel horse .I just picked it up from a friend that couldn't get it to turn over. I replaced the PTO switch and the neutral switch and now I have it turning over but no spark. I was thinking the coil but wanted to get someone elses opinion cause I am not sure . Any help would be appreciated.

thanks Dave

[boovuc 1,090]

Welcome to Redsquare!

On a 520H, no spark could still be an issue with the safety interlocks though it usually WON'T turn over. I would do this just for s*#ts and giggles.

Directly wire the PTO, Neutral switch and the seat switch to eliminate any open circuit with them. Next, buy some spray can electrical contact cleaner and take apart each and every electrical contact and connector on that machine, spray it with the contact cleaner and put it back together. (Yes....there are a lot of them).

Try to fire it up again. before and while cranking it, look at the gauges to see if they are active. Look for any idiot light when you turn the key on. (Good indicator of an issue).

Let us know what happens.

Good Luck!

[bowtiebutler956 650]

You can just put a test light to the +side of the coil, crank it over, and see if your getting 12v.

Matt :flags-texas:

[hckypck7 1]

Thanks ,I will try tomorrow with test light. I have already cleaned all the electrical connections that I could find. The engine wouldn't turn over until I replaced the switches and the seat switch was already bypassed. I checked for spark at spark plugs and nothing, so if I don't find 12v at coil then that is the problem. Thanks again

[hckypck7 1]

I tested the coil today and it has 12 volts getting to it. So now what should I look for? I took flywhheel off and clean the inside of it but still no spark.

[hckypck7 1]

I was wondering if the regulator is what I should be looking at next?

[lincman 3]

I have the same problem with a '97 520H Onan. No output from the secondary side of the coil. Resistance checked out on primary and secondary sides. Still no spark, got a solid 12.93 volts at the coil. So I then preceded to run a jumper from the + on the battery to the + on the coil. (this was prove the low oil pressure cut out switch) and yes you guessed it no spark. Maybe I have to run a jumper from the neg - side as well? I don't know, but about 2 weeks of this. I miss my horse!!

[Save Old Iron 1,566]

Guys,

getting 12 volts to the (+) side of the coil is only half the equation. To produce a spark, the negative side of the coil must be grounded intermittently by the ignition module. The module is located behind the flywheel. The rubber collar on the crankshaft contains two magnets. Every time a magnet passes by the ignition module, the module lifts the ground from the (-) side of the coil and the coil fires.

So ...

a test light or a voltmeter attached to the (-) side of the coil should show 12 volts alternating with near 0 volt readings as the crank shaft turns. The onan ignition module is just a transistorized version of standard mechanical ignition points. The principle of operation is the same.

[Save Old Iron 1,566]

[2005 0]

i need to get in on this also i am working on a 18 horse twin onan {no spark also) changed coil..ignition control(behind flywheel)..plugs.. plug wires...ignition switch...and yep!! still no spark???? im stumped.....help!! want my horse runnin again:(

[Save Old Iron 1,566]

2005.

follow the instructions in the post i made earlier this morning - tell me what you have (or don't have) as far as voltages on the (+) and (-) coil terminals. You need 12 volts on the (+) coil terminal ALL THE TIME while the ignition switch is in RUN OR START.

The (-) terminal needs to be toggling between 12 volts and near ground while the engine is cranking or running. Again, you can see this with either a meter or a test light. We need to know what is actually happening in the circuit, not just a list of parts replaced. Sometimes if you have the parts already available it is easier to just shotgun in the parts. Sometimes, as you see now, that technique doesn't always work in your favor.

I'll be glad to hang in there with all you guys and work on your individual issues until resolved. Just keep asking questions if you don't understand.

[hckypck7 1]

I tested the coil like it tells u to in the manual and it is within all specs. I tested the + side and got 11.75 The - side did nothing while cranking over so in the manual it states its the ignition module.

If you agree with this please let me know ,cause the ignition module is almost 200.00. they can get it in 3 days .

Thank you for helping me on this.

[rmaynard 15,403]

Price sounds a little high to me. I've seen them on eBay for $139.00 recently.

[2005 0]

Price sounds a little high to me. I've seen them on eBay for $139.00 recently.

i got mine straight from onan $89.00 ..best price found yet!!

[hckypck7 1]

That price from Onan sounds good to me. Do u have the info how to get in touch with them. Or a phone number. Thanks for any info u can give me.

[Save Old Iron 1,566]

I tested the + side and got 11.75 The - side did nothing while cranking over so in the manual it states its the ignition module.

the 11.75 voltage at the coil (+) concerns me a little - too low if the engine is not cranking, a little too high (maybe) if the engine is cranking when you made the measurement. Measure the battery voltage while the engine is not cranking. Write that down. Measure the battery voltage while the engine is cranking (as best you can as it will be jumping around on a digital meter).

Let me know what those two voltages are.

Let's also do a sanity check before you spend $100 - $200 on an ignition sensor. Since the function of the sensor is to ground the ignition coil and then lift the ground to create a spark, we can simulate that action by hand. Insert a spark tester into one of the spark wire leads and connect the tester to a good ground. Disconnect the sensor wiring from the coil ground (-) terminal. Place one end of a jumper onto the (-) ign coil terminal, let the other end hang free. Put the ignition switch in the RUN position. Take the free end of the ground wire on the ignition coil (-) terminal and touch the wire to a known good ground, wait a second, remove the wire from ground and then repeat that process. The spark tester should produce a healthy spark every time you lift the wire from ground. If you get a good spark by manually performing the function of the ignition module, the ignition module (or its wiring) is bad. You can then feel confident you need to spend money on a new ignition module.

[2005 0]

That price from Onan sounds good to me. Do u have the info how to get in touch with them. Or a phone number. Thanks for any info u can give me.

yep...onanparts.com. cheapest ive found.. good luck..

[rmaynard 15,403]

Currently there is a used sensor on eBay now for $49.99 or buy-it-now for $65.00.

[2005 0]

o.k. got a few minutes after work tonite to work on the tracter....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 then when i touch red lead from sensor it goes to .54 volts????? 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????

[Save Old Iron 1,566]

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.

[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.

thanks!! i will try with correct wirring and let you know how it went....and the red wire i was talking of came from the ignition control behind the flywheel...one red and other black

[Save Old Iron 1,566]

the red wire to the ignition module should stay at battery voltage - because it should be connected to the (+) ignition coil which is connected thru the ign switch to the battery.

the red lead for the ign module is actually the power supply to the module. It powers the transistor and magnetic sensor embedded in the epoxy case of the module.

the ground of the module is not the black lead - the black lead is what we will call the module "output".

the electrical ground for the module is the metal bracket that attaches to the engine block.

when the ign module sees the magnets in the flywheel ring, the module lifts the ground off the ign coil and causes a spark.

I have a few pictures of the inner workings of a module along with some magnetic sensor "plots" of the flywheel ring and its two embedded magnets. I'll get those out later today. It won't help you fix your issue but it will promote some understanding of how the system works.

[Save Old Iron 1,566]

I'll explain all this later - but for now - the green film is a sensitive to magnetic fields - iron particles embedded in a gel realign themselves to the fields of a magnet laid on the film. Basically gives you a visual image of a magnet's lines of force.

[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.

thanks!! i will try with correct wirring and let you know how it went....and the red wire i was talking of came from the ignition control behind the flywheel...one red and other black

o.k. im back ...heres how its wired now pos. post on coil has black wire from harness that carries my 12 volts to coil on pos.then condeser and red lead from ignition control(sensor from behind flywheel)and on neg post the black lead from ignition control..now im using volt meter and with meter hooked up i then introduce the red lead from ignition control to pos. term on coil and all voltage drops 12 to 1

then take the red wire from ignition control off pos. post of coil and voltage comes back to 12????? new ignition control from onan i put on last week???? could it just be a bad one????

[2005 0]

the red wire to the ignition module should stay at battery voltage - because it should be connected to the (+) ignition coil which is connected thru the ign switch to the battery.

the red lead for the ign module is actually the power supply to the module. It powers the transistor and magnetic sensor embedded in the epoxy case of the module.

the ground of the module is not the black lead - the black lead is what we will call the module "output".

the electrical ground for the module is the metal bracket that attaches to the engine block.

when the ign module sees the magnets in the flywheel ring, the module lifts the ground off the ign coil and causes a spark.

I have a few pictures of the inner workings of a module along with some magnetic sensor "plots" of the flywheel ring and its two embedded magnets. I'll get those out later today. It won't help you fix your issue but it will promote some understanding of how the system works.

this is good i have it wired just as the pic. shows....