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Discussion Starter #1
Hello! New to the forum here and happy to have found this. I have my brother's '10 TRX420FE 4x4 ES with no/intermittent power. It was being ridden and stopped running abruptly (temp and mil lights came on). Bike was restarted but ran only briefly before quitting again. Key was cycled and when turned back on there was no power to the display.... anywhere... no click at the solenoid... no blown fuses... nothing.. nada... zip... zilch. I was able to get the display, Neutral, Temp and MIL to light up after disconnecting the Engine Stop/Fuel Pump Relay (WPC 8P) however start button still dead. Having the relay plugged in and turning on headlight switch resulted in high pitch whine/buzz from relay. Also, with headlights disconnected turning on light switch turns on display backlight, no backlight with headlights plugged in. I have checked every connector for corrosion and solid seating, have checked battery and fuses. I have full power from battery at main 1 but only 3.7v at main 2. I got a new Engine Stop/Fuel Pump relay, installed it today and result was intermittent power to the display, singing/whining relay, pushing start button or crossing starter solenoid posts stops whining and blanks out display. I am at a loss... even having the relay powered directly from the battery to check continuity of the relay will cut power to the display, disconnect from the battery and display lights back up steady on.

Was reading a reply from a technician the other day on one of those "Ask" sites and he mentioned something to do with the light switch on the left handlebar but never completed the thought or information to the inquirer.

Any ideas?? All grounds are solid, contacts clean, battery posts clean, ran the entire loom (in original condition w/o splices or add on wiring) and no rubs or cuts - despite that the symptoms appear to be an intermittent connection. Appreciate any feed back.

BTW a huge thanks to Bryan K. for the FSM link. Was able to get a legible schematic finally. :grin:nerd
 

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Welcome to the forums from East tx!!! Can't really help you out on the fuel injection stuff lol all I know is carburetors but it's definitely electrical

Sent from my XT1609 using Tapatalk
 

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First thoughts are it sounds like a poor battery negative/ground cable issue somewhere. Either on the frame where the wiring harness is grounded, or on the motor where the battery cable is bolted to ground?

Next thoughts relate to troubleshooting your way through sections 21 & 22 of the FSM.

Welcome to the forums!
 

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I have not researched your model ?, but does that model have a bank angle sensor ?, if it does ?, that will kill all power if it was set off so to speak.
 

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^^^ Yes it has the BAS and diodes.^^^ The Section 21 troubleshooting flow chart gets into that right off the bat.
 

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I agree that the battery and/or cable connections is your most likely source of the problem. There is one other thing that I would investigate, though. You said you have 12v at Main 1 fuse and 3.7v at Main 2 fuse. Both of those fuses are fed directly from the battery + terminal and should show 12v. If you are sure about the voltage readings that you reported, then I would investigate the connection quality on the wire that goes from the battery + terminal to the Main 2 fuse. If you have a corroded or weak connection, that could cause a voltage loss.
 

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Hi: If you don't have 12 vdc on the main fuse 2 -- you have a bad 3P connector or red wire wire leading to the connector or fuse is bad. When checking the fuses leave them in place -- you will see a little gray dot on each side of the fuse test for 12 vdc on that dot with the other lead on the negative of the battery.

Like Ktriebol posted never read his post.
 
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Discussion Starter #8
Well after much testing and tracing, along with some head scratching and a few colorful mutterings to myself, I believe I am close to solving this puzzle. I don't have an HDS pocket tester so reading any DTC codes is out of the question. However, I was able to trace it down to what appears to have been a fault/malfunction of the BAS or something in that part of the system. For whatever reason unplugging the BAS appears to have allowed a reset. I noticed the battery was getting down late in the day so I put it on a charger. For giggles I turned the key on and the display lit up perfectly, fuel pump cycled and pushing the start button got massive clicks from the starter relay. Fingers crossed that baby fires right up in the morning. Otherwise I may go back to smoking and take up drinking on a regular basis. j/k thanks for all the replies.
 

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Well after much testing and tracing, along with some head scratching and a few colorful mutterings to myself, I believe I am close to solving this puzzle. I don't have an HDS pocket tester so reading any DTC codes is out of the question. However, I was able to trace it down to what appears to have been a fault/malfunction of the BAS or something in that part of the system. For whatever reason unplugging the BAS appears to have allowed a reset. I noticed the battery was getting down late in the day so I put it on a charger. For giggles I turned the key on and the display lit up perfectly, fuel pump cycled and pushing the start button got massive clicks from the starter relay. Fingers crossed that baby fires right up in the morning. Otherwise I may go back to smoking and take up drinking on a regular basis. j/k thanks for all the replies.
good deal, keep us posted !.
 

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Discussion Starter #10
Battery fully charged @ 13.3V (isolated from the system). Attach cables to battery and cycle the key causes an immediate drop to 12.5V. Cycled key again and dropped to 10.5V. Was able to jump start it from my pickup and runs fine until I disconnect the jumper cables then it dies immediately. All my years says that's a charging system issue, but in this day and age of computerized systems I know it may not be so easy. That's the latest. Have not found any problems in the 33P Gray continuity and voltage checks or the 33P Black voltage check. Obviously something is drawing some serious power when the key is cycled. Going to check the loom again for shorts but it's a pretty pristine loom, especially for a 2010, and I found nothing on previous inspection. A short in the stator?? Can't check the output if it won't run on it's own. (more colorful mutterings)

Ideas??
 

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Discussion Starter #11 (Edited)
Update Found a current leakage of 4.5A. No continuity on alternator yellow wires @ 5P connector, however, resistance between yellow wires is 2.2 ohms (more than twice standard).
Regulator/Rectifier Battery voltage on Red, continuity on Green, no continuity or resistance values on yellow wires.

With Regulator/Rectifier disconnected (Red and Green wire connector only) there is no current leakage.
 

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I would first of all look at the wiring diagram and see if one of the diodes in the system could cause a current drain if one of them shorted. If you suspect any of them unplug and check for continuity both directions (swap leads) through the diode. A good diode allows current to flow one direction only.

Next up eliminate the regulator rectifier as being a possible cause... it has rectifier diodes inside it that can short as well, if any were to fail.

I think I would revisit the Main 2 and test there too... like ktriebel and Melatv mentioned above.

From here its just a matter of running it down I imagine. Keep us updated if ya can?
 

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Discussion Starter #13
Diodes were tested already, and the Main 2 voltage was an error on my part it actually has battery voltage. I was thinking of the voltage from the 15A fuse when I wrote that for some reason.
I've been through every test/check in the mentioned FSM sections as well as others not mentioned (i.e. starter, battery, charging, BAS, PCM/ECM, lights-meters-switches, etc). Covering all the bases. Given that it runs when jumped from an external power source and dies when that source is removed, even in a modern day machine with a computerized system, it still has to point to the charging system. The Regulator/Rectifier is the only thing that removes that current leak. That should be the culprit... no??

Reinspected the loom and it's all good, no rubs, no cuts.
 

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....The Regulator/Rectifier is the only thing that removes that current leak. That should be the culprit... no??
Certainly can be! The regulator/rectifier has several rectifier diodes in it that can short when they fail. It takes only one of them to be shorted...

The troubleshooting flow chart is in section 19:



Before replacing the Regulator/Rectifier I would check the stator windings to verify no problem exists there.



Keep us updated if ya can.
 

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Discussion Starter #15
Thanks Retro... that section is what I followed to get the results I posted previously, first post of this page...

Found a current leakage of 4.5A. No continuity on alternator yellow wires @ 5P connector, however, resistance between yellow wires is 2.2 ohms (more than twice standard).
Regulator/Rectifier Battery voltage on Red, continuity on Green, no continuity or resistance values on yellow wires.

With Regulator/Rectifier disconnected (Red and Green wire connector only) there is no current leakage.
I see no problem with the stator based on the continuity/resistance results despite the resistance being twice the stated standard values. Was looking for a consensus confirmation of my resolution, that the regulator/rectifier is the problem, based on my findings of the troubleshooting tests/checks. Thanks again for the input/feedback, I appreciate it greatly.
 

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What is the voltage on the battery when you rev the bike Half throttle?
 

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Discussion Starter #17 (Edited)
Hi Melatv! The voltage is about 13.2 at idle and maxes about 13.3 at half throttle. My brother, the owner of the bike, and I concede that the battery is 7 yrs old and may well be past its prime so he's going to get a new battery for it. We'll have a better idea I think after that.

Correct me if I'm wrong but shouldn't the voltage hit around 14+ at half throttle??

Also, ran the bike for about 10 mins to let it get good and warm, plus I changed the oil so I wanted it to get circulated, rechecked for the current leak and it was minimal .001 - .003 microA and intermittent. There one moment gone the next... literally.
 

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Also, ran the bike for about 10 mins to let it get good and warm, plus I changed the oil so I wanted it to get circulated, rechecked for the current leak and it was minimal .001 - .003 microA and intermittent. There one moment gone the next... literally.
This sounds like the regulator/rectifier is shorting a diode too. I think you need a new one... but I'm reluctant to tell you on a forum to buy it, then find out later it was some other silly thing we never thought about checking. I'd feel responsible for you wasting $$$. Since it needs a battery anyway, I'd replace that and monitor the voltage again (for quite a while) before buying that regulator. In the meantime I'd still be snooping for other possible reasons for the current draw...
 

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Discussion Starter #19
That's kinda what I'm thinking also Retro. I've learned to be as thorough as possible before spending money... just for that reason. I believe the regulator/rectifier is the culprit here. On my very first inspection of the bike the + and - terminals of the reg/rect had corrosion, on a part that is sealed and shielded from moisture that raises flags to me. The voltage I got at idle and half throttle last night were not always steady readings either.

The bike has not been ridden rough, it's been a utility vehicle, back in the woods to drag out a few deer, et al, but never ridden hard or rough. I was of the belief that it was being ridden lately in short bursts and not enough for the charging system to keep the battery full. My brother told me that wasn't so though. Said just prior to it quitting it had been ridden for well over an hour. When he told me that, combined with the experience of the bike dying after jump starting and pulling a cable off, it really brought the charging system as the target. I haven't totally written off the stator, and I'm really hoping it's not, but I'm leaning more toward the reg/rect. My experience has been that if a stator shorts the engine will still run it just won't charge worth a dam. Shorting diodes in the reg/rect will let a charge through but not what it should be. I know there are exceptions to every rule though, that being said being thorough is the only way to be sure. :smile
 

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Anytime a regulator/rectifier is a suspect you can put your multimeter on AC volts mode and check for the amount of AC getting past the diodes... if one of those diodes are shorted in the regulator/rectifier, a high measurable amount of AC will be present (should only measure a few millivolts of AC) with the motor running.
 
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