Onan P-Series Ignition Module Replacement [Photos]

[lynnmor 6,762]

The procedure for checking the ignition parts is in the Engine Manual on pages 8-1 & 8-2.

[corpline 0]

Anyone have a picture or ignition module or know where it's located on 520H?

[corpline 0]

6 hours ago, Duramax7man7 (Mastiffman) said:

You can test the coil itself but on the Primary coil (small wire posts) as well as the secondary coil (main spark coil posts) for continuity and proper resistance.  I believe the secondary coil will be around 16k-19k ohms...

IIRC, You can also test the wires coming from the ignition module for signal as you are turning over the engine? 

 Either way, you can find all that you need to know from the demystification guide for testing the ignition components to find your issue. 

Anyone have a picture or ignition module or know where it's located on 520H?

[corpline 0]

Just to confirm secondary coil test for measurements, do you stick 1 Ohmmeter lead in the spark plug wire on the coil and 1 Ohmmeter lead to negative post? Ohmmeterresult of this measurement NO reading. Or do you stick 1 Ohmmeter lead in the spark plug wire connection on the coil and 1 Ohmmeter lead in the spark plug wire on other coil connection? Ohmmeter result of this measurement also NO reading. I agree you should get a Ohmmeter reading between 16K to 20K ohms. When measuring primary, I got 3.5 ohms so we know this is okay. I did discover shorter spark plug wire to be faulty (no reading) but not the longer spark plug wire (13K Ohms). Of course, neither wires would produce a spark on the plug. My guess this new ignition coil part is bad. I am still curious on the ignition module and where it's located. As mentioned when ignition is turn ON, I am getting 12 volt reading between YELLOW wire and BLACK & ORANGE wire. Looking at the schematic diagram I see ORANGE tied to PTO switch but how can I be getting 12 volts between YELLOW and ORANGE especially when ORANGE and YELLOW are tied together on the coil post?

[WVHillbilly520H 10,369]

2 hours ago, corpline said:

Anyone have a picture or ignition module or know where it's located on 520H?

It is located directly behind the flywheel.

[corpline 0]

Thank you WVHillbilly520H for the ignition ("trigger" labeled on spark circuit diagram) module pictures. I see from one of the pics on this module you have ORANGE (or maybe RED) and BLACK wire together in a insulated conduit which I noticed on 520H after removing the ignition coil I am working on. If that's an ORANGE wire then I just answered my question above (previous post) and but puzzled at spark circuit diagram because ORANGE wire shows on the diagram tied together with YELLOW and to PTO section (pic above). Anyone can maybe shed some light? If ORANGE and BLACK wires are coming from this ignition (trigger) module then this is like a "magneto" and sends pulses to fire spark plug but don't see this color described on spark circuit in the demystify document and wouldn't ORANGE and YELLOW (tied together) short itself?

Edited June 21, 2019 by corpline

[corpline 0]

Just going through a manual "lynnmor" had posted (P8-7) and found another diagram which shows the ignition (trigger) module and ignition coil wanted to share here. Thank you "lynnmor". This picture shows RED (which I called ORANGE) and BLACK wire attached to the + and - posts on the ignition coil. This explains my 12 volt reading between YELLOW and BLACK & RED (called it ORANGE because of the spark circuit diagram) wire. On this diagram I've put a question asking for the color of terminal connector 4. If this unlabeled wire is YELLOW then where's the ORANGE from spark circuit? Maybe ORANGE is in reality RED. 

Edited June 21, 2019 by corpline

[Duramax7man7 505]

Yeah that wire is the yellow one. You have it in your pic just like Cleat does... 

 Did you find the section in the manual to test the Primary and Secondary Ignition Coil winding's? 

 1.For the rest. First test and make sure that you have continuity from the battery Neg terminal to all of the grounding areas on the tractor including switches. 
 2.Test to see if you have power coming OUT of the fuse box from the batter positive terminal on voltage setting. If you do move to next step. If not, Fix fuse box issue. The fuse contacts can loosen up over time and or become corroded.

 3.Next, Turn your key on. Ground your multi meter and then test power coming out of all of the switches. Ignition switch, seat, PTO, etc... If all good, move to next step. 
 4. Test coil for proper resistance and NO Cross continuity between the primary (small terminals) coil winding and the secondary (spark plug wire terminals) coil. 

 If all good then you most likely have a dead ignition model behind the flywheel (black and red wire with white sheathe. Or a bad oil pressure switch. 

 Sounds like a stupid question but: DID YOU CHECK YOUR OIL LEVEL? 

Edited June 21, 2019 by Duramax7man7 (Mastiffman)

[corpline 0]

On 6/21/2019 at 5:31 AM, Duramax7man7 (Mastiffman) said:

Hi guys I had to take a break but wanted to address the questions "Duramax"'s test procedures below:

 

Yeah that wire is the yellow one. You have it in your pic just like Cleat does... 

 Did you find the section in the manual to test the Primary and Secondary Ignition Coil winding's? YES AND TESTED IGNITION COIL FINE

 1.For the rest. First test and make sure that you have continuity from the battery Neg terminal to all of the grounding areas on the tractor including switches. YES AND TESTED FINE
 2.Test to see if you have power coming OUT of the fuse box from the batter positive terminal on voltage setting. If you do move to next step. If not, Fix fuse box issue. The fuse contacts can loosen up over time and or become corroded. YES AND FUSES TESTED FINE

 3.Next, Turn your key on. Ground your multi meter and then test power coming out of all of the switches. Ignition switch, seat, PTO, etc... If all good, move to next step. 
 4. Test coil for proper resistance and NO Cross continuity between the primary (small terminals) coil winding and the secondary (spark plug wire terminals) coil. YES AND TESTED IGNITION COIL FINE

 If all good then you most likely have a dead ignition model behind the flywheel (black and red wire with white sheathe. Or a bad oil pressure switch. Ignition model wires (RED and BLACK) measures to be 705 ohms but with Ohmmeter and when I crank the engine I don't get a "flicker" on the Voltmeter or Ammeter. Since this module is behind the flywheel and I will need to go to Autozone and get their flywheel "puller" I thought I research a bit more about this ignition module behind the flywheel. Found test procedures posted by Garry for ignition module. BTW, Oil pressure switch looks to be open but shorted this switch to see if I get a "spark". NOTHING. All signs point to ignition module. Anyone have experience with these modules going bad?

 Sounds like a stupid question but: DID YOU CHECK YOUR OIL LEVEL? Oil level is fine but Oil pressure switch seems to be stuck on open but bypassed this to continue troubleshooting.

 

Edited July 8, 2019 by corpline

[gwest_ca-(File Mod) 10,488]

I think you will find the oil pressure switch on the 520 has no control over the ignition.

Low pressure puts the oil light on.

Normal pressure closes the other set of contacts to provide a ground for the hour meter. That way the key can not get left on to add hours to the meter when not running.

 

Garry

[corpline 0]

Thank you Garry. Please check this step 3 on Ignition Module testing procedure you had posted which I may add to be VERY useful.

Edited July 8, 2019 by corpline

[Duramax7man7 505]

I thought that was the whole point of the oil pressure "switch". Was to keep the engine from being ran in the event of low oil pressure, either from bad pump, clogged valley or low oil. 

 Maybe you could pull it out and spray some parts cleaner into the hole. Maybe soak just the end in high concentration of hot dawn dish soap water and spray out a few times. Use a multimeter and see if that allows continuity. 

 

[corpline 0]

Andrew I will do that once I get spark issue fixed. I just pulled the flywheel and removed the ignition module. I've applied the test procedure Garry uploaded and took the part off and metered the device and "no es bueno". I got no reading what so ever even running a strong magnet in front of it. Now I got to figure out who has this part and order it. You guys have been a wealth of information on diagnosing the issues. I wonder how the part got fried...

Edited July 8, 2019 by corpline

[lynnmor 6,762]

One source: New

[gwest_ca-(File Mod) 10,488]

13 hours ago, corpline said:

Thank you Garry. Please check this step 3 on Ignition Module testing procedure you had posted which I may add to be VERY useful.

Wheel Horse used 12.5hp, 14hp, 16hp, 18hp, 20hp and 24hp Onan engines. It is possible Wheel Horse used a low oil pressure cutout switch on some models but not aware the 520 was one of them.

A tractor model number and serial number to find the correct wiring diagram would confirm it.

 

Garry

[Duramax7man7 505]

Garry's right about a lot. lol 

 I would contact Lincoln at A-Z tractor parts. He has a TON of parts last time I checked and response quickly and is a nice guy. 

Edited July 9, 2019 by Duramax7man7 (Mastiffman)

[corpline 0]

Just placed an order with Lincoln (717) 821-2542. He is a nice guy! Thank you Andrew.

[corpline 0]

Post-Mortem Analysis of this ignition module I see that any large current or voltage would fry this device. For example, if someone trying to jump start a Wheel Horse with an old-style charger/starter where amperage is greater than (10A) or if someone bypassed in-line fuse and went directly to ignition module looking to test for spark. The specifications of this ignition module device says it's rated for 12 VDC but it doesn't mention how much current. This device requires 12 VDC to activate it and then it switches between battery voltage and 1 VDC which causes ignition coil to fire whenever the magnet passes by. Since this device is expensive (around $271 brand new) there is 20A fuse in-line but believe this is excessive and it should be at lower rating. Just wanted to throw this out and get your opinions. Also, if anyone knows what is the maximum current specified by this ignition module device.

[WVHillbilly520H 10,369]

9 hours ago, corpline said:

Post-Mortem Analysis of this ignition module I see that any large current or voltage would fry this device. For example, if someone trying to jump start a Wheel Horse with an old-style charger/starter where amperage is greater than (10A) or if someone bypassed in-line fuse and went directly to ignition module looking to test for spark. The specifications of this ignition module device says it's rated for 12 VDC but it doesn't mention how much current. This device requires 12 VDC to activate it and then it switches between battery voltage and 1 VDC which causes ignition coil to fire whenever the magnet passes by. Since this device is expensive (around $271 brand new) there is 20A fuse in-line but believe this is excessive and it should be at lower rating. Just wanted to throw this out and get your opinions. Also, if anyone knows what is the maximum current specified by this ignition module device.

Hope this helps...

[lynnmor 6,762]

Adding a John Deere label to the box adds about $170. 

[onanparts.com 178]

On 7/10/2019 at 6:48 AM, lynnmor said:

Adding a John Deere label to the box adds about $170. 

That's a healthy premium for just adding JD to the label! Maybe I should get some of those labels and increase the price by $161.00 ? :) No? Not a good idea? OK, no changes planned! :)

 

 

[corpline 0]

Finally was able to get all parts installed and fired up wheel horse right after I cleaned up the carburetor from seating a few years. I didn't have a mower battery so used car battery to get it jump started. But what was so strange when wheel horse was running, I disconnected battery and wheel horse would stop running. Based on my previous experience with other types of mowers the engine would continue running even when battery is disconnected. Just wanted to ask the forum if this is normal operation for the wheel horse.

 

In summary, ignition coil and ignition controller were bad which could not derive spark. Thank you to everyone for your help. This forum gets 100 thumbs up!!!

[gwest_ca-(File Mod) 10,488]

The electronic voltage regulators must see battery voltage before they will regulate the charge current. Some tractors have a decal on them warning not to run without a battery as some components will get fried.

 

Garry

[Duramax7man7 505]

On 7/31/2017 at 8:50 AM, Duramax7man7 (Mastiffman) said:

Okay, 

INTRODUCTION:

 So if you've problem solved all other aspects including troubleshooting of the ignition module, and coil  (which you can find in previous posts in this thread!) regarding your non-starting Onan engine with electronic spark control and come to the conclusion that you need to replace the Ignition module, keep reading. This is a decent step by step and doesn't require the engine to be removed the from the tractor. Although it might be a little easier to work on while on a workbench.

 The part numbers for the Module and ring if needed are below:

Ignition Module: 166-0785
Spark Ring: 166-0767

Here is a list of the tools that I needed to complete the job from beginning to the end. They are named from left to right in the photo with the tools at the top of the photo last from top to bottom.

TOOLS:

[From left in Photo]
1. T25 (for the stator screws but also may be three 5/16" head screws)

2. Phillips and Flat Head Screw Drivers
3. Needle Nose and standard slip joint pliers

4. Flywheel puller with 2 5/16" x 18 grade 8 bolts and washers (mine is technically a steering wheel puller)

5. 7mm and 5/16" deep well 1/4" sockets

6. 3" 3/8" drive extension, 3/8" socket 3/8" drive, 5/8" socket 1/2" drive and 5" 1/2" drive extension. 

7. 1/4" Socket Driver
8. 5/8" open end box wrench
9. 3/8" and 1/2" drive ratchets

[Top of photo- top to bottom]

10. Flash light (optional but very helpful at times)
11. Pry bar (used to lock flywheel from turning)

12 1/2" Torque wrench

13. Old Tooth Brush (for cleaning of dirt if needed)




PROCESS:

- Obviously the first thing to do for safety sake is to shut of the fuel at the tank and remove the battery cables
- Next, remove the two screws that hold the fuel pump onto the shroud, move the pump off to the side and replace the screws into their holes for safe keeping.
- Carefully pull the fuel pump away from the shroud enough to work the hose clamp out and use the pliers to pinch the hose clamp and remove the vacuum line for pump. 




- Tie the fuel line, wiring harness, choke cable and battery cable all out of the way towards the rear of the tractor allow easy access to remove the shroud.



- Next remove the air cleaner box cap, then air cleaner cap and air cleaner tray by removing the three 5/16" screws from the carb and the two 3/8" screws from the tray and put all aside and out of the way. 

NOTE: Close the Choke all of the way and stuff a clean paper towel into the top of the carb to prevent debris contamination.

- Next, twist the air filter box bracket to the left (right side up and left side down) to clear space and use the 7mm, 5/16" and 1/4" socket driver to remove the black condenser wire, the red and black ignition module wires and the yellow ignition switch wire from the coil and then remove the coil using the 3/8" socket. (optional as it can be kept on the shroud but makes it a little more difficult.)
-  Next loosen the rear cylinders top shroud and engine hoist mount bolt with the 1/2" 3/8" sock and extension. (no need to remove the bolt as the shroud just needs to move freely. 
- Next, locate the wire retaining clip at the top of the shroud by the coil and open it up so the oil pressure sensor, stator and ignition module wires can all be removed when taking out the shroud.
- Last step before removing the shroud is to disconnect the throttle to gov arm spring and the throttle cable using  the 5/16" socket and driver.
-Next locate all of the shroud bolts and remove using the 3/8" socket.

 

 

- To remove the shroud, pull the bottom out first and then shift the entire piece upwards while working it from underneath the rear cylinder shroud, underneath the filter box bracket and over the flywheel on the left side. Work slow so you don't bend or brake anything and it will come off pretty easily. 
- Although everything was fairly clean in comparison to other engines at this step, my shroud was dirty and this can slightly decrease air flow which is important to maximize and keep optimal with an air cooled engine. 
 

 

 

So I took mine outside and pressure washed it to give it time to dry completely before reinstall. 

 

Shroud off... 

 

 

- Next, place the pry bar into the fins of the flywheel and lock the flywheel in place by placing the handle of the pry bar under the foot rest. Then use the 5/8" sock, 1/2" extension and loosen up the flywheel bolt about 3/8" -1/2" out of the hole. This needs to stay mostly in as a pressure point for the puller.

- Next, remove two of the flywheel grill center bolts and then use your two 5/16" grade 8 bolts and attach the puller to the flywheel while keeping the puller parallel to the surface of the flywheel to allow equal pulling pressure on both sides of the puller while cranking on the center pressure bolt on the puller. 



- Now it's time to remove the flywheel.  It may be a good idea to use the 5/8" open ended box wrench to stop the flywheel bolt from turning while cranking on the puller center bolt. 

- It should only take a 3-5 good cranks after finger tightening the center bolt and the flywheel will give a good pop and be ready to be pulled off. Don't forget about the flywheel bolt first!

 

- Next, carefully pull the flywheel off of the crank being very careful not to get caught on the stator itself. 

 

 

My flywheel was pretty dirty on the inside and between the magnets so I felt it necessary to use the toothbrush and air gun to clean it out. 

 

- Now you'll need to remove the stator by using either 5/16" socket or T25 torque bit or driver. 

 

- Next, set the stator off to the side securely on a clean rag or similar. Underneath, you'll see the ignition module on the bottom side of crank. There are two 5/16" head machine screws. Remove those and open the wire retaining clip on the side of the gear cover and the module comes right off. Make sure not to lose the black rectangular insulator that goes between the module and gear cover. That needs to be there. 

 

I'm not 100% sure but I have a theory that these modules may potentially go bad from getting covered with grass and debris over time from not blowing out the air shrouds with a leaf blower or air gun after each use. This debris builds up enough to cause insulation around the module. The module being an IC (Integrated Circuit) is designed to handle only so much heat. Over time the extra heat and expansion with contraction when cooled back down causes a when point in the modules chip circuitry and eventually breaks. Thus causing the engine to shut off during operation for the first time. Once the engine cools, the chip materials contract, allowing the circuit to bridge again only until the engine heats up enough to break that signal and then becomes a cycle until replaced. 

- Moving on.. While everything is out, if needed (or your OCD kicks in), clean the cylinder heat syncs and general area before re-installation of the Module, Stator, Flywheel and Shroud. Mine wasn't to bad so I quickly used the toothbrush and air gun to break free any layered gunk and blew it off with air. 



-Next, once the insulator, module (and spark ring if chosen to) and stator are all reinstalled and screws all snugged up, carefully put the cleaned flywheel back on, install the flywheel bolt with a tiny tad of anti-seize on it and use the pry bar again in the flywheel fins but with the handle on top of the foot rest and use the 5/8" socket, extension and 1/2" torque wrench set to 55lbs and tighten up the bolt. 

 


At this point, go ahead and reinstall the Shroud making sure that the fuel pumps vacuum line is accessible through the front hole in the shroud, along with the shroud bolts, coil, coil wires (spark, condenser, module and switch) and tighten rear shroud bolt. 

NOTE: Yellow Switch wire, red module wire and black condenser wires all go on the Positive coil terminal (7mm nut) which should be on the right side of the coil. Only the black module wire goes on the left terminal. 

 

Connect the throttle to Gov arm spring, throttle cable, install the fuel pump vacuum line again and replace mount screws. 




- Lastly, re-install the filter tray, remove the paper towel from the carb, along with installing the air cleaner, pre-filter and clean cap and shroud to filter tray pipe. Then connect the battery and turn the fuel back on. 



 This should get you going again. 




 I think that I got everything but please feel free to comment on anything that I missed as far as documenting the steps or ask any questions about the process. 

 Hope this helps you see that it's not that bad of process to replace the ignition module (And spark ring if needed as some recommend replacing the module , ring and coil all at the same time).

I had to first remove this module from a P220G that was on my bench and awaiting repairs but the whole process took me a few hours. A good Saturday Morning task to be up and running by the afternoon for some work before the heat hits. I also ran the tractor for well over and hour after install to insure all was well. I went from a warm up process of idling and then a lap around my property. Did that a few times while repairing a cutting deck and then installed the cutting deck and mowed the lawn. No issues. Ran great! 

Take Care and God Bless!

Andrew C.

 

 

[wh315-8 439]

Very good information, needed this a month ago. Done it pretty much as you. Just add need parts tray to keep track of all the hardware. Lol. Would maybe emphasize reason to keep bolt in flywheel is also to keep flywheel from falling to ground and breaking when it pops and it can be a loud pop. Thank You for great detail.