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Discussion Starter #1
Hey guys it's been a while but I'm back, just picked up a 2010 Honda Rancher 420 AT for $1250 with only 750 miles! It's in great shape, but has an issue. The owner told me "it needs an ecm", I didn't ask him much about why he thought so. What it is doing is this, turn on the key, fuel pump kicks on everything seems normal except for the fact that the gear indicator blinks -- (pretty sure it's giving me a code) and the start button and shift buttons are unresponsive. So far the only thing I've done to it is cross over the solenoid to ensure it wasn't locked up, and it actually hit a time or two. What is the first thing to check? I'll get the number of blinks of the gear display tomorrow.
 

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It sounds like you got a good deal assuming the trans is in good shape! You're starting in the right place for diagnosis too... you can get a copy of the '09-'11 420AT service manual and read section 14 to familiarize yourself with what is in store for you before beginning. First step is to read all of the DLC codes then follow the troubleshooting flow charts. It is a time-consuming process... but keep us posted on your progress if you can.
 

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You got a great deal on that. The IRS rear end is worth what you paid for the whole bike (people swap them into footshift 420's)

These things have a ton of electrical crap on them, so they aren't fun to troubleshoot, but if you have the patience it will be worth the effort.
 

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Discussion Starter #4
Thanks for the link to the Manual and yalls input.
Alright got the codes off of it, the first one is -- -- - which according to the manual means either low or high voltage to the shift angle sensor. Then I am getting -- -- -- -- - - - - which means either low or high voltage circuit to the EOT sensor (one of the symptoms is the cooling fan comes on which mine does) And finally I am getting - - - - - - - - which means either low or high voltage to the TP sensor. Am I right to conclude that I need to start cleaning?
 

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Also make sure the battery is good and fully charged. These newer bikes can act funny with an iffy battery on them.
 

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Discussion Starter #7
Alright I've been messing with it some, took the battery out to charge it. Took the angle sensor off cleaned it and the connection, found the EOT sensor unplugged, cleaned the connection and hooked it back up, which it didn't quite click in so I'm going to have to mess with it some more. Put the battery back in, turned on the key........ nothing changed, still the same thing. So I started trying to figure out why it wouldn't start, pulled out the plug, good strong spark, checked the compression...... 60 at wide open throttle, course that's with a cheap HB compression tester but, it doesn't crank much harder with the plug out as with it in. Shot it with a little ether, besides one "scare the crap out me" back fire it didn't change much. Here's a picture of the sensor in that goes in the air box, he had it siliconed in and the black and blue wire are cut. Anything wired about that? And yes, I do believe this bike has seeen allot of "mud".
 

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Discussion Starter #8
I just swapped the entire throttle body and air box from a running 08 Rancher. Still the same, cranks good, doesn't hit a lick. Kinda lost now. Also, I've been crossing over the solenoid because the starter button does nothing, the previous owner said that it was broke. I pulled it apart to ensure it wasn't caked with mud and it's clean. Hmmm
 

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Discussion Starter #10
Just did that, got it fired up! Although I don't know if that helped, I hooked it up like you said and heared the same noises as I do when I just turn the key on. Still had to cross it over the solenoid, what I did was just sit there a crank on it longer than I like to, until finally it started trying to start, at that point I unhooked the jumper wire and kept cranking until it eventually started. Now, it started and idles great! Nice to hear it run, no smoke either, but as soon as I touch the throttle it dies i even tried hooking the wire back up but it does the same, so I'm just letting it sit out there and idle at the moment. I'm thinking I need to isolate my problem by swapping the sensors from the throttle body until I find the one it doesn't run with. Which I am guessing to be my tps being that's what one of the codes I was getting.
 

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Discussion Starter #11
Going to see if I can get the EOT sensor hooked up better tomorrow, I have a new angle sensor on its way, any other suggestions?
 

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The temp sensor that goes in the airbox has to be hooked up and functional for the motor to run. Check the IACV on the throttle body right away....and those scotchlock splices are junk... they begin to corrode right away, so you'll need to take them off from the harness and fix whatever the PO was trying to cobble up there... If there are any more cobbles like that on the bike, those will need corrected too. You can use the wiring diagram in the back of the service manual to help you sort out any wiring messes you might find. The connectors to each and every sensor on the bike need to be clean and snapped together like they belong... look for any damaged plugs with bent or pushed in pins and either correct the pin alignments or replace the affected sensor/device. Remember to turn the key off before you disconnect or reconnect any harness plugs... the two electronic control modules can be ruined instantly if you don't... Hopefully the PO hasn't smoked them both already!
 

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Discussion Starter #13
Here's what I've down so far,
installed a new angle sensor,
hooked up the EOT sensor correctly,
cut out the scotch lock connectors and used heat shrink connectors and the cleaned the connection,
found a connection (that I can't remember what's it for but I knew it was for the electric start) that the pins were bent over and full of mud.
and removed the pcm and cleaned the connections on it. Now remember, I pulled the entire throttle body and air box off a great running bike, sensors and all and plugged them up. Turned on the key and once again nothing changed, still giving me the same codes, do I need to delete them? Shift buttons unresponsive, but hey! The start button works now, also, I fired it up and it is having trouble idling now, just dies. You said I need to clean every sensor on the bike, I've done a thorough inspection of everything and I think I eliminated all the "cobbles" on the bike. Just keep cleaning?
 

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Discussion Starter #14
Here's an video of the codes it's giving me, does the flashing engine light mean anything? I really appreciate the help

 

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Discussion Starter #15
Just put it manually in gear, won't start, cranks but won't hit, put it back in neutral, fired right up. With it running I put it in gear, then I tried to give it throttle, died, tried to start it while in gear, won't hit, put it back in neutral fired right up. Somehow this is all related, was the PO right when he said the needed a PCM?
 

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Discussion Starter #16
What's getting me is that the 3 codes it gives me I have resolved, angle sensor (cleaned the connection and a new sensor installed) EOT sensor (was unplugged so I cleaned and reconnected) TP sensor (swapped the entire throttle body over). YET, it's giveing me the same codes, the same symptoms, do I just need to delete the codes? Do I need the special tool to short the connector or can I just use wire?
 

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Hi: you can just use a jumper wire to reset the codes.
 

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Discussion Starter #20
Jumped the two on the left side, pretty sure it clear them. Turned the key off then on again and once again everything is the same. So I about to go to pull all the plastics off and pull it back to the pressure washer and wash it down real good, let it dry and clean and check every connection on the bike. I've been just using parts cleaner in a can, that work?
 
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