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I have a 27 HP Kohler Model CV 740 engine retrofitted into a Poulan 48 Inch mower.It originally had a 25 Hp Briggs,and the replacement engine had a modified wiring harness connector to interface with the Poulan.Everything ran fine, till I replaced a mower deck belt.After that, it would not start.Motor turns over, but will not start.Starting fluid does not help. There is no fire at spark plugs. I checked all wiring,and the KILL circuit for the Kohler is good( White Wire) (not grounded) if clutch is depressed, and seat switch is made, and PTO is disengaged,so safety circuits are being satisfied.I suspect the DSAI Ignition units are bad, but I cant imagine why both would go bad at same time,no fire to either spark plug.
Is it normal for both coils to go bad at same time? Is there some circuit that I am missing that would inhibit the ignition modules?
The SPEC# CV740-0040 Coil= 625840-5 (or S ).
I hate to buy the coils if there is something else wrong.
Any help is appreciated on this matter.

Disconnect the coil kill wire and give it a try.

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Carscw said:

Disconnect the coil kill wire and give it a try.

Sent from my iPhone using LMF

Click to expand...

Already tried that, still no firing of plugs.The kill wire is the white wire in the connector from engine.It is not grounded(clear).

Kohler has had problems with voltage spikes frying the modules, If there is not a clampling diode between the leads off the electric clutch it can cause a voltage spike when the clutch is turned off. There has also been cases where jump starting the engine, then disconnecting the leads that where connected to a dead battery has fried the modules.

Kohler says the black wire is the engine kill wire and not the white. the red lead should have 12 v with the key on, when tested at the ignition module. Kohler tested for the DSAI is to remove the blower housing disconnect the leads on the modules, make sure the connections are clean. Check for continuity on the black lead to a good engine ground with the key off. Should have continuity. Then turn the key on at check for 12v on the read wire. If those two test pass, then replace the modules.

And if the electric clutch doesn't have the clamping diode then you need to install one.

True, the wire on the module itself is black, but it changes to white at the connector for the chassis wiring.This is the white wire to which I referred.It is not grounded till the switch is turned off, or a safety interlock is tripped.Refer to KohlerEngines.com,wiring diagram 24 690 07 revision C. If there is a newer revision ,please direct me to it.
I will double check the connections, and continuity of all wiring.
CRAP like this ignition makes me long for the good old days of points and condenser.They gave a lot less trouble,and the new stuff does not improve anything except the profit of the company that sells the spare parts.
Kohler is a disappointment,and proof that corporate greed has overcome the desire to make a durable, robust,long lasting product.
A 1N4002 diode costs less than a nickle to add to the circuit.And look at the trouble it might have saved.Of course, a nickle times many thousands of motors will pay for your greens fees.Of course, this is just my opinion, I could be wrong,however,I will never make the mistake again of buying one of their engines.I bought this one based on their previous reputation from many years ago.
RIP: Grandpa's Kohler.
Thank you for your help.::smile:

Not having the diode in the system is not Kohler's job. Poulan installed the electric clutch, they should have added the diode. Make sure you are blaming the right person or company.

I have been an electronics engineer for over 50 years, before CMOS,during the vacuum tube days.I have designed circuits using all current technologies as they advanced thru the decades.An engineer that would design a static sensitive or spike sensitive circuit without protection is obviously under pressure from the accounting department or he is not really an engineer to begin with.I tend to believe the former. I have been there,but refused to do that.I have had many career changes because I would not compromise good design principles to save a few pennies.Pass the buck is their motto, but in this case, pass the pennies.
As I said, it would only cost pennies to add the diode at the manufacturer stage,and it would not hurt if Poulan and Kohler added it.A little redundancy would be nice, but then again, the executives might have to forgo a round or two of golf if they spent that penny.
I have modified the standard circuit to incorporate surge protection, flyback (CEMF) protection,static protection,and overload protection,all with spare parts I had lying around.New cost of the components, at consumer prices was less than 25 cents.In bulk, about 2.5cents.
Kohler is not the only company that does this, I have repaired automatic transmission control computers that suffered from the same problems,and I always add a free wheeling diode to prevent repeat failure.It is a sad statement on corporate greed when disconnecting a battery can destroy an expensive module.
Perhaps I am just an old dinosaur that has outlived his time,and it is time for the new throw-away society to have it's day in the sunshine.Sooner or later, you will run out of "stuff", and the landfills will runneth over.

Kohler added diodes (2) to the wiring harness awhile back, and the electric clutches were not only frying the diodes but was still getting the modules. Even had one case on an EFI engine, where the tech had his laptop connected to the ECU diagnosing a problem, and when they shut the electric clutch off, acts like a generator when winding down, not only did it fry the ECU, it also fried the guys laptop.

The new DSAI modules are supposed to be designed to withstand more of a power surge situation, and have removed the diodes from the wiring harness. But still require the PTO clamping diode for added protection.

This engine is a 2002, and I do not see any additions to the wiring harness.In view of your feedback, I will change the diode to a higher rating,an SK7091, which is a 1000volt 6 amp diode.I will also install the same diodes across the fuel shut-off solenoid coil and the operator presence relay, and the starter solenoid coil.This takes care of all coils (4) that I see in the circuit.
I will also install an MOV,15 volt,(#2V015)in series with a 5amp fuse,from battery Positive to ground,in the harness,so it will be present when battery is connected or removed.This will arrest any voltage spikes when battery cables are connected or disconnected.The MOV is a one-shot device, and it protects by Crow-Barring the supply very quickly,if it exceeds the rated voltage, thousands of times faster than a fuse, so the fuse is in there to prevent melt down if the MOV fails in a shorted mode..I will install a small indicator lamp or LED across the fuse to indicate when it has failedlight on=failure=replace MOV) Most of the time the MOV's protect and fail, then go open, with no visible indication,so the indicator is necessary.
Maybe with these additional modifications I can get good service life from this engine.
My first riding mower was a tricycle type, tubular frame,semi-pneumatic tires, a belt clutch, and a 36 inch cut.single speed,just forward and reverse.Gearbox, not a transaxle. It had a 5hp Briggs engine, and it would cut tall grass the full width with no problem.
So when I upgraded to an 8hp, I was disappointed,it could barely cut the 40 inch width.Then I went to a 10 Hp, and it would strain trying to cut the 42 inch width.I began to suspect that someone was fudging the HP numbers, and sure enough, my suspicions were true.Now they only state TORQUE,not HP of their engines.
The last good HONESTLY rated small engine I remember was a 1986 horizontal shaft Briggs 16 HP. I still have it, and it runs good.A single cylinder in an MTD frame, that was made before MTD had it's own brand on the market.It was sold by JC Penny,had hydrostatic drive,hydraulic lift,came with a snow plow and road scraper blade.It had a driveshaft to a gear-box on the mower deck that drove the mower belts.I have had very little trouble with this machine,replaced 1 axle seal,rebuilt front axles by replacing them with boat trailer spindles with bearing-buddies, one set of rings, a head gasket, carb kit, and that is it.Almost 30 years service, and still going strong.
It will still outperform the 27 HP Kohler any day.It had a 50 inch cut, and didn't slow down in heavy pasture grass.The Kohler has a 48 inch cut, and stalls if you go too fast.
Wish somebody still made them the way the Briggs was made back then.
(sigh).

How long must we put up with this squirrel ?

I guess you are right,I am a bit of a squirrel.
Even a little crazy, perhaps, for longing for the days when a man's handshake was as good as a written contract and his word was his bond.
When you could go to sleep at night with your doors unlocked.
When, to get a degree in engineering, you had to be a real engineer,not a quota filler?
When companies prided themselves on the quality and durability of their products, and there was honesty in advertising instead of hype.
With all of the modern tools, like CAD/CAM, manufacturing things should be easier and better than ever, but it is impossible to put common sense into a computer program.There are many farm tractors from the 1940's '50, and '60's still doing productive work every day.I wonder why? Could it be that squirrels made better products?
All of the old squirrels at Kohler must have retired,or gone to that great nest in the sky,because the nuts on the ground have taken over.
The prime focus now seems to be "Get it out the door, we will fix defects when the occur in the field!"
And that is not just Kohler, look at microsoft,for instance: how many updates and versions will it take to get it right?
As many as it takes to keep the money rolling in.
I realize a company has to be profitable to exist,but to put profit above all else is wrong,and will eventually lead to it's demise.
Of course, I am still applying yesterday's yardstick to today's measurements, and with the new throw away society, short product lifetimes have become the norm, and they do not know any better.
The small engine manufacturers were recently taken to court to justify their exaggerated HP claims and the result was they would start listing TORQUE only,instead of HP.
Even then, they have found ways to cheat:The motors are tested with no mufflers,no air cleaners, and at RPM's that are far above normal usage.
Even a half rate mechanical engineer knows that the most effective power is where the HP and Torque lines cross.
How about a good HONEST HP RATING AT 3600 RPM? Is that so hard to do?It was done for generations before,why not now?
And how much benefit has been gained with all of the solid state ignition systems?I would put the old B&S,with points and condenser against any of the new engines that are rated at twice the HP.
Anyone up to the challenge?
Put up or shut up is what they used to say when I was growing up,a century ago.
Sure, I am on a rant, but it is just wasteful to have to buy 2 coils at over $100 when a 4$ set of points and condenser would achieve the same thing:FIRE THE SPARK PLUGS!
This old squirrel will get off his soap box and go back into his nest.As soon as I get it fixed, I am selling that piece of crap mower, with it's piece of crap engine,and I will fire up ole Bessy with the single cylinder 16 Honest HP B&S and will seek out a used mower of similar age for my grandson to use to help me mow 10 acres.
I realize my words may be provocative to some, but my grandpa always said:"If you throw a rock into a pack of dogs, the one that gets hit will be the one that hollers!"
I will leave the truth of my words to ring in the ears of those other poor victims of modern "Engineering", and the nuts that are everywhere on the ground.

Goodbye.

"If you throw a rock into a pack of dogs, the one that gets hit will be the one that hollers!"

I don't think you are a squirrel, but I do think you are the dog that got hit by the discharge of to many paper wrapped capacitors, not a rock.

Hurt, did it?
I hope it does not leave a scar.:smile:

Not at all, but seeing you replied, that cap must have shocked you again.

Touche, mon ami.

Today I cut open the wiring harness for the DSAI ignition.Inside a piece of shrink tubing were 2 diodes, in parallel,in series with the power(+) wire feeding the modules.This configuration does not offer any effective protection from the Counter EMF from the clutch coil.It will prevent a polarity reversal if someone connected battery backwards.When the clutch coil magnetic field collapses, it generates a magnetic field of opposite polarity, and any nearby parallel conductors will become an antenna,so the best place for the diode is across the coil itself as close as possible to the coil terminals.The diodes, being in series with the DSAI coils introduce a voltage drop of .7 volts,which is typical of all silicon-junction devices. If the diode is placed across the clutch coil, there is no voltage drop to the DSAI modules, and they will receive full battery voltage.
With the diodes in series with the plus wire, an antenna is created from the wire length going to the coil up to the junction of the diodes,and in effect, is a single turn transformer primary.A lot of current can be injected into the system with this configuration,. Instead of helping, the placement of the diodes made the situation worse.A MOV of appropriate rating across each DSIA module would have been much better.
Anyway, when my new module kit arrives, all potential sources of spikes and transients will have been taken care of by proper selection and placement of protection devices.I will gladly provide a schematic for anyone interested.

tsimm1 said:

Today I cut open the wiring harness for the DSAI ignition.Inside a piece of shrink tubing were 2 diodes, in parallel,in series with the power(+) wire feeding the modules.This configuration does not offer any effective protection from the Counter EMF from the clutch coil.It will prevent a polarity reversal if someone connected battery backwards.When the clutch coil magnetic field collapses, it generates a magnetic field of opposite polarity, and any nearby parallel conductors will become an antenna,so the best place for the diode is across the coil itself as close as possible to the coil terminals.The diodes, being in series with the DSAI coils introduce a voltage drop of .7 volts,which is typical of all silicon-junction devices. If the diode is placed across the clutch coil, there is no voltage drop to the DSAI modules, and they will receive full battery voltage.
With the diodes in series with the plus wire, an antenna is created from the wire length going to the coil up to the junction of the diodes,and in effect, is a single turn transformer primary.A lot of current can be injected into the system with this configuration,. Instead of helping, the placement of the diodes made the situation worse.A MOV of appropriate rating across each DSIA module would have been much better.
Anyway, when my new module kit arrives, all potential sources of spikes and transients will have been taken care of by proper selection and placement of protection devices.I will gladly provide a schematic for anyone interested.

Click to expand...

Just saw this from tsimm1... yes, very interested in schematics! Thanks for your posts...I'm not an engineer but followed your posts. I have the DSAI module on my machine and wound up just disconnecting the kill feed. The circuit is not well documented on the service manual so I appreciate all your advice.