[Michaelt71991]

So about a year ago my 12 honda TRX420FPM [rancher 420 4x4,manual shift,power steering] would occasionally miss once good and warmed up. The issue got worse but the bike would still run. So I thought it was the igniton coil going bad, I ordered a non-oem coil [caltric] and replaced it. The day I replaced it I rode for about 20 minutes and it died. It blew the 10amp igniton fuse. The only spare I had on hand was a 15amp, so I replaced it to get me back home. On the way home approximately 5 minutes going about 30 mph the bike flat died. Didn't spit or sputter just completely dead like you hit the kill switch. I pulled the seat to check the fuses and noticed the igniton coil was really really hot and no fuses were blown. So I hauled the bike home, ordered a new ignition coil, replaced it and still no spark, replaced the spark plug, plug wire still no spark. I'm getting 12v on both sides of the igniton coil when the key is turned on. I pulled all the wiring harness apart to check for broken wires etc. All looks good. I took it to honda bc I dont have a peak voltage tester, they kept it for a week and said the stator was not testing and offered to change it for like $900, I picked the bike up from them ordered a brand new stator and pulsing/p/u coil and replaced them both myself. Still nothing. When You turn the key on everything looks normal, fuel pump kicks on etc. But if you pull the plug and hold it to the block or something grounded it's not sparking at all. I have checked the kill switch and it's good. I am dumbfounded. Honda said they "checked" the voltage regulator/rectifier and it was supposedly good. Any advice or repair manual/ wiring schematic link would be greatly appreciated, thank you!

 

[LBZ_Duramax]

Try holding the rear brake handle and starting it. This will override the gear position sensor safety.

 

[retro]

I think the china ignition coil you put on it smoked the ICM. Those china coils measure way under the Honda primary winding resistance spec, which overheats the ICM (CDI) severely and soon fries it. I have been warning folks for a long time now about this particular issue. It looks like you learned it the hard way... let us know what you find and what it takes to fix it so we can help others. Welcome to the forums!

 

[Michaelt71991]

I tried the rear brake and it didn't help. I will order a cdi box and let yall know how that goes. Thank you!

 

[retro]

You can get a copy of the service manual from the manuals forum:
https://www.hondaatvforums.net/foru...nual-help/50817-service-manual-downloads.html

Check out the ignition system section and follow the diagnostic steps for no spark before you buy an OEM CDI, in case you have a shorted harness somewhere or other issue we have not thought of yet. There are wiring diagrams in the back of the manual if you need them.

 

[Michaelt71991]

Okay got service manual, I ordered peak voltage adapter and performed all checks. My initial voltage on coil [yellow/green wire] is 12.8v which drops to 6-9v while cranking. Troubleshooting in manual says to check pcm connector blue/yellow and green/white wires to make sure they have at least 0.7v. I have 17v going to them. I also have 17v coming from my stator. The manual doesn't say what to do if voltage is high only it needs to be at least 0.7v. Any recommendations?

 

[shadetree]

Okay got service manual, I ordered peak voltage adapter and performed all checks. My initial voltage on coil [yellow/green wire] is 12.8v which drops to 6-9v while cranking. Troubleshooting in manual says to check pcm connector blue/yellow and green/white wires to make sure they have at least 0.7v. I have 17v going to them. I also have 17v coming from my stator. The manual doesn't say what to do if voltage is high only it needs to be at least 0.7v. Any recommendations?

are you getting a neutral light when checking for spark ?, new plug ?, new c.d.i. ?, new spark plug coil ?, all oem from honda ?, or more china junk parts ?.

 

[retro]

Okay got service manual, I ordered peak voltage adapter and performed all checks. My initial voltage on coil [yellow/green wire] is 12.8v which drops to 6-9v while cranking. Troubleshooting in manual says to check pcm connector blue/yellow and green/white wires to make sure they have at least 0.7v. I have 17v going to them. I also have 17v coming from my stator. The manual doesn't say what to do if voltage is high only it needs to be at least 0.7v. Any recommendations?

I don't have a copy of the service manual... PCM connector Blue/yellow and Green/white wires... what component do those test? .7 volts peak spec sounds like the pulse generator... is it?

I don't get how you measured 17 volts on the stator... where are you probing and how are you reading 17 volts? Is that AC volts? At cranking speed?

The stator windings are for battery recharging and have nothing to do with the ignition, BTW.

Did you replace that china coil with OEM Honda yet?

 

[Michaelt71991]

No the 2 wires are from the ckp sensor which supposedly tells the pcm when to fire, the 3 wires from the stator are yellow and they all checked out. Brand new stator and ckp sensor [they come together] OEM. Only other thing I have not replaced is PCM, just curious why I am getting 17volts DC from [brand new]ckp sensor when manual says check to make sure you have 0.7v minimum, before I order a new pcm

 

[Michaelt71991]

And yes I replaced China coil with OEM honda also

 

[retro]

Ok, I figured you were talking about the crank trigger when you mentioned .7 volts. So 17 volts DC should not be there.... its impossible for that sensor to produce much more than 1 volt at cranking RPM and battery voltage is below 13 volts DC.

So those wire colors must be the wrong ones to connect your peak voltage adapter onto? Or else a stator wire might be shorted to the CKP wire somewhere inside the main harness?

If I were you I would test that crank position sensor at its own plug. Then check the wires from its connector going to the ECM in case the stator wiring is shorted to the CKP sensor wires inside the main harness.

I wish I had the correct service manual so I could follow along with confidence. Are the wire colors in these images a close match to your manual?

 

[Melatv]

Hi: Did you have your meter on the AC scale when doing the test.
Bike on and try starting when doing tests

Y/Gr wire on coil should read 100 VAC leave wire on the coil when testing. .


Bu/Y -- Gr/W should read 0.4 - 0.7 VAC

 

[retro]

Hi Melatv, I think Michaelt71991 mentioned that he is using a peak voltage adapter to measure the CKP, so meter should be set on DC volts mode (or millivolts DC scale, depending on the meter) shouldn't it? Thanks for joining this thread!

 

[Michaelt71991]

Yes that is while cranking, 0v initial on ckp 17v while cranking. And yes using peak voltage adapter.That schematic looks identical. Here is mine

 

[Melatv]

Hi Melatv, I think Michaelt71991 mentioned that he is using a peak voltage adapter to measure the CKP, so meter should be set on DC volts mode (or millivolts DC scale, depending on the meter) shouldn't it? Thanks for joining this thread!

Yes when using the PV adapter the meter should be placed on DCV and the meter should read the DC

 

[Michaelt71991]

Retro I will test the ckp wires with the stator wires tonight for continuity and see if its shorted in the harness somewhere

 

[Melatv]

Hi: I checked the resistance on a good CKP sensor which I have here and it reads 143.3 ohms.

 

[Michaelt71991]

So after all was said and done, it was the ECM. Got it fixed, thank you everyone for yalls help!

 

[shadetree]

So after all was said and done, it was the ECM. Got it fixed, thank you everyone for yalls help!

thank you for the update !.