JD 322 ignition module testing

[angelugs]

I have a JD 322 that is only running on 2 cylinders. I have a technical manual and have been trying to run down the problem. Basically I've been checking for continuity on the parts in the ignition system. Everything seems to be okay till I get to the ignition module. When I test the contacts one way I have continuity everywhere I'm supposed to. But when I switch the leads from my meter I have no continuity on the same contacts I just previously checked. The chart says I should have continuity on certain contacts regardless which way the meter leads are connected. It looks to me like I have a bad ignition module but at over $300.00 to replace it I don't want to THINK that's the problem. Has anyone else ever checked continuity on the ignition module's contacts and can verify they had flow no matter which meter lead was on the contacts?

Thanks in advance for your response.

 

[Amvcane]

If you know which cylinder is not firing could you just switch that cylinders coil pack with a working cylinder and see if your problem moves?

 

[angelugs]

Thanks for your input. I've tried switching spark plugs AND the coil leads on the cylinder that's not firing. The cylinder still didn't fire with a plug that was firing on another cylinder. Switching the leads with a coil that was firing on a good cylinder still didn't cause the bad cylinder to fire.

 

[radios1]

I think you probably don't have sufficient compression on that cylinder, you should do a compression test on it.. compression testers are not expensive, or you could just rent one.. I'll bet if you pulled the plug on that cylinder, and connected the wire to it, and grounded the threaded end, you'd see the spark jump the gap on the plug..

 

[angelugs]

Thanks for the input. I have pulled the plug, grounded it and looked for spark but saw nothing. Also connected a timing light to the non-firing cylinder plug and got nothing that way either. Haven't done a compression test but at this point I see no reason to do so.

 

[Amvcane]

Do you have a copy of TM1591? Section 240-20-38 to 240-20-44 covers everything you need to diagnose your symptions. I’m not sure how to post pages from a pdf.

 

[Amvcane]

I’ll try


They are not in order.

 

[radios1]

this reminds me of the 3 cylinder ignition module for an outboard boat engine they wanted $300 for.. nuts.. there's only $20 in parts in it!!. I took it apart, reverse engineered it, made a new circuit board, and it worked fine. it used a cheap fiber board, which arced over, and made a carbon trail, I used a fiberglass board, and gave it extra spacing. they used coils under the flywheel to make 400Volts, which went to the ignition module, water and high voltage don't mix.. anyway, you might be able to find a used module somewhere cheaply.. although it's possible to replace this junk with an aftermarket CD ignition system at a cheaper price, for someone that knows how to wire it..

 

[angelugs]

After talking with a few John Deere repair people who agreed that it SOUNDED like a bad ignition module, I broke down and bought one. Anyone want to buy a new ignition module? Yep, that isn't my problem. So I'm going back to page one and going through the troubleshooting steps looking for the problem. Don't really know anything I can ask to help me out. Just thought I'd post an update.

 

[radios1]

After talking with a few John Deere repair people who agreed that it SOUNDED like a bad ignition module, I broke down and bought one. Anyone want to buy a new ignition module? Yep, that isn't my problem. So I'm going back to page one and going through the troubleshooting steps looking for the problem. Don't really know anything I can ask to help me out. Just thought I'd post an update.

is the ignition module getting full voltage? is it getting a proper signal from the crank sensor? how about a kill wire, is that causing the problem?. and does the ignition module fire a spark coil? is so, is THAT good?.. I don't have wiring diagrams for this..

 

[angelugs]

I'll start troubleshooting from square one tomorrow. Had to get my mowing done and take a break from the 322. As far as answers to your questions radios1, everything seemed to check out up to testing the ignition module. I THOUGHT I was reading the chart shown in the service manual correctly but evidently not. If your curious about a wiring diagram there's one available online. Just Google "jd322 ignition wiring diagram" and you'll see it. I'm just focusing on the pulsars, ignition module, plugs/wires and coils for now.

Thanks for your interest in my problem.

 

[radios1]

I'm getting a strong feeling there's a corroded or loose connection between the ignition module and the coil..(check that) but I'll check for the wiring diagram.. I found the wiring diagram, and found you have 3 "pulsars" one for each coil. in this case, it may be one of those causing the problem, as everything you did so far narrows it down greatly. the ignition module you said you tried a new one, so that's not it, and you said you swapped the coils, that's not it either.

 

[angelugs]

This evening I started the troubleshooting process again. Everything electrical checked out. Took a minute and thought about everything I'd done to this point and the results I got. Starting to think it could be low compression in the cylinder I've never seen fire since starting the process. Dug out my OLD compression tester and found the rubber end split/brittle and the valve core wouldn't hold pressure anymore. I tried checking pressures anyway and it looks like the suspicious cylinder is only getting around 70 - 80lbs. compression. Checked another and it looked closer to 100lbs. Specs. call for 113lbs. minimum and 14lbs. variance. I'll have to run down another tester somewhere so I can feel confident in the readings. I'll check for continuity on the positive wire for the dead cylinder from it's coil back to the ignition module too.

If it needs valves or rings that will be outside of my DIY capabilities. Got any idea what a engine rebuild would cost?

 

[radios1]

This evening I started the troubleshooting process again. Everything electrical checked out. Took a minute and thought about everything I'd done to this point and the results I got. Starting to think it could be low compression in the cylinder I've never seen fire since starting the process. Dug out my OLD compression tester and found the rubber end split/brittle and the valve core wouldn't hold pressure anymore. I tried checking pressures anyway and it looks like the suspicious cylinder is only getting around 70 - 80lbs. compression. Checked another and it looked closer to 100lbs. Specs. call for 113lbs. minimum and 14lbs. variance. I'll have to run down another tester somewhere so I can feel confident in the readings. I'll check for continuity on the positive wire for the dead cylinder from it's coil back to the ignition module too.

If it needs valves or rings that will be outside of my DIY capabilities. Got any idea what a engine rebuild would cost?

a rebuild kit here ENGINE COMPLETE REBUILD KIT - READ DESCRIPTION!: Yanmar Tractor Parts is $656.65 that's do it yourself, parts only, they don't mention if the pistons and rings are oversize, which may be needed, maybe you ask what you want, so, if someone has this done at a shop, labor has to be figured in.. maybe someone else has a better estimate on having it rebuilt. there is also the possibility of a repower,(different type of engine) this make(yanmar) seems pricey for parts.. OH, check your valve lash first!..

 

[angelugs]

Compression on all cylinders checked out good. With that being said, I don't see how my problem can be mechanical unless the pulsar for one cylinder has come loose from the block and is dangling inside the flywheel housing. I'm not ready to "dig that hole" yet.

Haven't check the valve clearances but can't see that causing the misfire with the compression reading I got from the "dead" cylinder.

Now what?

 

[radios1]

Compression on all cylinders checked out good. With that being said, I don't see how my problem can be mechanical unless the pulsar for one cylinder has come loose from the block and is dangling inside the flywheel housing. I'm not ready to "dig that hole" yet.

Haven't check the valve clearances but can't see that causing the misfire with the compression reading I got from the "dead" cylinder.

Now what?

with your updated info, you don't have a mechanical problem, the problem must be the ignition module is not getting the pulse from the "pulsar" to fire that one cylinder.. bad "pulsar".. you have checked everything else.. that cylinder will NOT fire without a spark..

 

[angelugs]

Checked pulsar on bad cylinder again today per tech manual procedure even though I've done it a half dozen times before. According to the test the pulsar is working as it should. Compared the brightness of the blinking test light on the bad cylinder to what it looked like on a firing cylinder and it looked the same. That's the only test the manual gives for the pulsar. As I understand it the only thing the pulsar does is break the low voltage circuit which in turn causes the high voltage to be created for the spark plug. Checked the coil again and, per manual, it tests fine. Other than resistance values there's no other indicators for a bad coil. I'd have A LOT of tearing down to do to get to the pulsars and since they're checking out okay I don't think that's where the problem lies. Having said that, with this type of ignition system there's not that many places to look for a problem and I think I've looked at them all. Hate to think I'm at the point of trial and error till I purchase and replace the right part.

 

[radios1]

Checked pulsar on bad cylinder again today per tech manual procedure even though I've done it a half dozen times before. According to the test the pulsar is working as it should. Compared the brightness of the blinking test light on the bad cylinder to what it looked like on a firing cylinder and it looked the same. That's the only test the manual gives for the pulsar. As I understand it the only thing the pulsar does is break the low voltage circuit which in turn causes the high voltage to be created for the spark plug. Checked the coil again and, per manual, it tests fine. Other than resistance values there's no other indicators for a bad coil. I'd have A LOT of tearing down to do to get to the pulsars and since they're checking out okay I don't think that's where the problem lies. Having said that, with this type of ignition system there's not that many places to look for a problem and I think I've looked at them all. Hate to think I'm at the point of trial and error till I purchase and replace the right part.

FIRST, check for a corroded or loose connection between the ignition module and the coil!.. what you should do, is put a voltmeter across the primary coil wires, and crank the engine, if the meter don't jump when cranking, then a "pulsar" is bad, despite the other tests. the "pulsar" needs to send a strong enough signal, and at the proper voltage levels to trigger the ignition module, which sends a pulsed signal to the coil, which creates the spark.. one of these tests are fooling you!.. something has to be bad.. if you had a means of switching the "pulsar" signal from on cylinder to another, and checked for spark, and you got a spark on the plug, then you know it's a bad pulsar!..

 

[angelugs]

After fighting this problem for the better part of a month I finally figured it out. Turned out I had a bad ignition coil. What took me so long to fix it was the bad coil still checked out with the tech manual specs. every time I put a meter on it. After going through the entire troubleshooting procedures listed in the manual NUMEROUS times I finally decided I had to start replacing parts until I found the problem. Since I'd already purchased an ignition module and it wasn't the problem I decided to go with a new ignition coil next. I know a coil is more expensive than a pulsar but I wasn't looking forward to removing all the parts necessary to get to the pulsar so I went with the coil.

So in summary I'd say I learned one thing and was reminded of another: Don't believe EVERYTHING you read in a tech manual .... and when having to purchase parts to find the problem, don't start with the most expensive part.

I want to thank everyone who tried to help me get my 322 running smooth again.

By the way, I still have the BRAND NEW unused JD ignition module (AM876024) I'll sell for less than you'll get one from a dealer.

 

[radios1]

After fighting this problem for the better part of a month I finally figured it out. Turned out I had a bad ignition coil. What took me so long to fix it was the bad coil still checked out with the tech manual specs. every time I put a meter on it. After going through the entire troubleshooting procedures listed in the manual NUMEROUS times I finally decided I had to start replacing parts until I found the problem. Since I'd already purchased an ignition module and it wasn't the problem I decided to go with a new ignition coil next. I know a coil is more expensive than a pulsar but I wasn't looking forward to removing all the parts necessary to get to the pulsar so I went with the coil.

So in summary I'd say I learned one thing and was reminded of another: Don't believe EVERYTHING you read in a tech manual .... and when having to purchase parts to find the problem, don't start with the most expensive part.

I want to thank everyone who tried to help me get my 322 running smooth again.

By the way, I still have the BRAND NEW unused JD ignition module (AM876024) I'll sell for less than you'll get one from a dealer.

how is that possible though, you said you swapped coils, and still didn't get a spark to that cylinder.:confused2: