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In my lifetime, I have seen many flywheels with damaged magnets and loose magnets, but I only replaced one flywheel for weak magnets. It was a Yamaha Timberwolf. Just so happens, the engine ran, but the lights didn't work - the owner wanted the lights to work - how hard can it be to get lights to work? When I checked the wiring diagram, I found that the lights worked on AC right off the alternator. The unit had two alternator windings - one was for charging the battery - the other was to power the lights. The voltage was low on both windings, but was over 25 volts AC at 3000 rpm to charge the battery. However the output to the lights was only about 3 volts (just barely made them glow). The stator had been replaced by the Yamaha shop, but they were at a loss as to why the output was so low. I installed a used flywheel and not only did the lights work, the engine started easier and had more power. In almost all cases where I have seen one spark just as the starter button was pushed and sometimes another spark when the starter button was released, the problem turned out to be a faulty stator. The spark was caused by surge, but, one time I did find a weak flywheel. It's rare, but it does happen.
 

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Discussion Starter #22
So finally figured it out at long last. It was some resistance in the big round connector I think it’s got 9 wires. The red wire had corroded in the plug in the past, and someone cut the red wire out of the connector, and used an insulated stab on connector. Made me look at the rest of the connectors inside the plug and there was small traces of corrosion. The green/red wire a piece of the connector inside had corroded off. I used an exacto knife and scraped all the connectors inside the plug. Viola, got spark and fired up. Pretty sure that green/red wire was the issue, have to see what it goes to in the schematic when I get a minute. Might have to redo that wire, like someone else did with the red
 

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I had the exact problem with my 2000 trx300ex I bypassed the reverse rev limiter box and it's sparked
and run fine
Hey guys I have a 2001 300ex that lost spark, or mostly lost spark. When turning over, I get a couple sparks, and then nothing. Come back later, maybe get a few sparks again, then nothing. The plug had only been used for maybe 5-6 rides, was new last year, but tried a new plug and no help. Replaced cdi box with 2 other boxes, one used and one brand new, still no help. Tried 2 other coils, one used and one brand new, still no help. Tried another pulse generator and stator (both used)- no help. All 3 coils measure properly per the service manual. Both pulse generators and both stators measure properly per the service manual. Took measurements right at the cdi plugs to also test wiring. I'm getting 12V on blue/white wire right at the cdi, the 12V supply is lost when either the kill switch or key switch is open, so I believe both switches are working. Green wire is grounding properly when not in reverse, and opens when in reverse. I even disconnected the wire at the reverse switch and grounded it to be sure. I'm about out of things to test or replace at this point. Any further ideas? There is just not much to the ignition circuit, so this is getting frustrating.
 

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i know this is old topic but i have a 2006 300ex no spark. from the beginning the key was left on and killed battery. after recharging battery it would turn over (crank) but not start. checked and no spark. i read and printed this forum topic and have done every test with the acception of output of the yellow/white wire from stator. the fuse is good. so far i have tested the 3 prong yellow wire plug and the yellow/white wire and all have continuity and aren't grounded to engine case. my neutral light works and reverse light works. i am a auto mechanic so i can at least say i can follow the diagnosing procedures that were described by the 2 members on this topic. as i am typing this i am sure i tested the pulse generator, coil, neutral switch, reverse switch, power and ground to icm. i am not a parts changer but i had to start somewhere. so i replaced the pulse generator even though it pass the resistance test. i looked at my stator and tested it again while side case was on the bench. i have 12 volts to regulator. i looked at the flywheel and the pick up tab for the pulse generator was still in place and with the engine at top dead center the timing marks were aligned. i tried a new coil. i tried a new icm. while i was working on it and from cranking it so much i burned up the starter sol. and replaced it. after i replaced the starter sol. i notice that i no longer had ground on the green negative wire to sol. so to crank it i had to ground it. so no spark not even 1 or 2 flickers. now here is the weird part and it might be important. if you unplug the gray reverse wire and the neutral wire and have key on and jump the starter sol. the engine tries to start. it fires a few times and stops. if you put a spark tester on it and observe the spark it fires ok the first 2 revolutions and then has week spark. am i on to something? can the reverse inhibitor cause a no spark condition since it also can control the rpm in reverse by reducing the spark? it is a very expensive part and any input would be very helpful. or don't be shy if i'm doing something wrong.
thank you,
mark
 

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The yel/wht wire from the stator is simply a parallel connection to one leg of the stator to feed the rev limiter - it serves as a tachometer feed. The rev limiter can be disabled by unplugging the gray wire from the reverse switch - the reverse switch simply provides a path to ground for the rev limiter. The stator serves no function in the ignition system except to supply AC to the rev limiter and charging system.

Besides checking continuity and voltages, you first need to clean all ground connections and assure all the ground connections are - this includes the connection of the engine to the neg side of the battery either through the frame or a ground wire. 90% of all ignition problems are connections and 90% of all connection problems are grounds.

Be sure to check the resistance of the spark plug cap - a broken resistor will affect spark. Get past all this and get out the peak voltage tester and prepare to check output voltages.
 

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thanks for the reply. also can a bad reverse inhibiter cause it not to crank(turn engine) and cause it not to have spark. i know some people like to skip over things and that's how you become a parts replacer. after working on this i also look like a parts changer. i have followed your posts and have everything as it should be except for the signal to starter solenoid to the green and orange wire for it to crank. i do get power to the yellow and red wire when i push start button. i have the analog and digital meter plus the the peak voltage adapter. it just seems so strange to me that with the neutral and reverse switch disconnected i then have spark even though it's weak. only way i can get it to crank the starter is to ground the green and orange wire to solenoid.
 

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I'm having a problem finding a gr/or wire - light green goes to the neutral switch, dark green goes to the reverse switch - there is a grn/red wire that goes to the reverse inhibitor - it is a ground wire for the unit - when it's in reverse, the g/r wire is connected to ground through the clutch switch to allow the starter to work when in reverse, but it's only needed when the reverse switch is closed and the reverse light is on.

Have you checked the ground on the ignition coil, frame ground and engine to frame?
 

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i am sorry i should of stated that the starter solenoid harness is green and orange but it plugs into a yellow/green of the wiring harness. the yellow /green goes to the plug of the reverse inhibitor that is a 2 wire plug. i hope that makes more sense.
 

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OK - yes that makes more sense - it makes no difference which wire on the solenoid plugs into the wire of the wiring harness - the yel/red wire is hot when the starter button is pushed - the y/g wire is grounded by the clutch switch through the reverse inhibitor - make this test; unplug the wires at the clutch switch - jump the grn/red wire to the neg side of the battery and see if the starter button closes the solenoid - if not it's probable the inhibitor module may be defective.

Here's the ignition circuit isolated and below that is the starter circuit - the two are not interconnected except for the starter lockout. Fix the starter circuit first and then tackle the ignition.
4261


4262
 

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ok,
i can ground the green/red wire and have neutral switch, reverse switch and every other connector connected and the starter sol. engages and turns the engine. the clutch switch was already previously tested so no fault there and it also makes the click noise when you engage the clutch switch. i do believe the no crank is due to the reverse module. the reverse module is not grounding the negative side of solenoid. i also tried the gray wire by-pass and have tested both neutral and reverse switch and i have stripped the wire harness from battery to the modules. also checked the neutral and reverse switch at modules and the continuity is good as well as 12 volts to black and white wire. the kill switch is also tested and working correctly. i also have checked the harness connector to the handlebar switches. i also think it is possible that the reverse module could also be causing my no spark. is the rev. limiter built into the reverse module? what happens when you reach the rev. limiter? does it limit the spark or maybe change the ignition timing. what module controls the rev. limiter? either way i think i will need the reverse module to at least repair the starter issue. i know i may seem naive. i know your credentials and they are very impressive. i started at the ford dealer as a tech when i was 20. i'm now 57 and even though many people can be certified technicians on paper doesn't mean any hands on experience. many techs. get a repair order and say how much am i going to make on this job. which i may have done earlier in my career but i found out that when you get your repair order was to say what do i need to do to fix it. i know i'll get paid and the next day when i get to work the customer wouldn't be there and i wouldn't have a so called come back. plus you type much better.
thanks,
mark
 

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Gee, that was a lot of info and my brain is so tiny o_O Forget everything I said earlier, I was confused about the model I was looking at - I was pasting pics of the correct ignition and quoting connections from another model.

The reverse inhibitor affects the starter motor function and has nothing to do with ignition - it simply prevents the solenoid from closing when in gear (F or R) until the clutch is pulled in.

The ICM has the rev limiter built into it - the yel/wht wire from the stator provides an AC frequency the ICM interprets and cuts spark as much as necessary to limit speed to a preset RPM - the pulse gen tells the ICM when to send the voltage signal to the coil. If you have 12v on the blk/wht wire at the ICM and a 3 to 5 peak volt signal on the blu/yel wire and a 100v peak pulse from the ICM to the coil and no spark, the coil or a ground is the culprit - if there is not a 100v pulse on the grn/red wire at the coil, the ICM is the culprit.

Hope this clears the fog and helps more than I have been helping up to this point. :unsure:
 

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thanks that was the answer i was looking for. for now i will just leave a jumper to ground on the starter solenoid start from the very beginning on the ignition. there is always a chance you can do a step wrong or miss a step. we are leaving tomorrow for a week and i am going to forget about it for a little while at least.
thanks for all your help,
mark
 

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Works for me - I left IL this morning for WI and will be gone a bit also, but I will check the forums each evening or morning as time allows.
 

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well i decided to get back to this no spark. with peak voltage set up on my meter. blue/ yellow wire at engine connector is 4.5 dc. the yellow and white to engine is 13 ac. i have 0 at black and yellow at coil. all while cranking. i am wanting to know if you know what the voltage should be on stator y/w wire while cranking. if you have signal from the pulse generator and all power and grounds to icm do you even need the signal from the y/w wire to have spark. i am also on my 3rd icm so i thing i can rule that out. i am about to put it outside and hopes someone steals it.
thanks,
mar
 

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You have a bad ICM

If the blk/wht wire has 12v DC at the ICM and the pulse coil has a pulse, the ICM should send a 100v pulse to the coil via the blk/yel wire when the trigger pulse is transmitted to the ICM - the yel/wht wire is for a signal that can be used as a tachometer feed - there is no tach, but the ICM reads the signal to know what speed the engine is running at. If the ICM fails to send a pulse to the coil and everything else is working, the ICM is the problem by elimination.
 

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so the two readings from the pulse generator and from the stator are correct? just to know for the future.
thanks for all your help.
mark
 

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Honda does not publish definite values for the older machines, but based on the values that work for the newer machines, 3 to 5 volts is good from the pulse coil, but............

I just reread what you posted earlier and I see something that is wrong - you should not have voltage on the yel/wht wire to ground - that indicates the stator is shorted to ground. I was under the impression you had checked the stator? In the very first post you state, "Both pulse generators and both stators measure properly per the service manual." If that was the case, you checked continuity from each yellow to another (A to B, B to C, and C to A) - the y/w wire will have continuity to all three, but be near zero to one yellow lead while checking the same as yellow to yellow (the near zero reading is the lead the y/w is connected to - measuring wire to wire and not the coil windings). Now the only way to have AC voltage to ground is if the stator is shorted to ground - check each stator lead to ground - resistance should be infinite or OL - if it has continuity, the stator needs to be replaced - I do not know if a shorted stator will affect spark, but it will affect battery charging.
 

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when i said i had 13 ac voltage at y/w wire that was with peak voltage adapter on my meter with meter red lead to y/w wire and meter negative to ground. that was with engine cranking. i previously tested (and i mean about 5 times) the stator 3 yellow wire continuity to the y/w wire. i had continuity to all 3 wires and none of the 4 wires are shorted to ground. as you state though that would be a charging issue not a loss of spark.
 
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