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· Registered
430 Posts
My bike has the LCV removed and will make the vary same noise. Some how at shut-down the ECM kicks the start relay. U can see it by connecting a volt meter to the starter terminal . I think a well placed clip diode should take care of it? It bugged the crap out of me when I first got the bike.I allways use the key in neutral.

· Premium Member
'04' Warrior - Super Fine Metallic Black
9,396 Posts
LCV (linear control valve) 101

I think I still needed the battery, with the 'labored' starting, cutting out and resetting befored starting up last night...

here's the video I took...
2012-03-23_14-03-26_929.mp4 video by emrge81 - Photobucket

first and second shut off is just with the key, 3rd is with the killswitch and THEN i turn off key...
SLEEP TIGHT .... that's the LCV (linear control valve) closing & reopening ... do a search with Bruce59 or AlanH and there is press on this subject :) .. HAS NOTHING AT ALL TO DO WITH THE STARTER, ETC........
Here's the link i suggested you read: How long does it take for you to start your warrior?
  • In a normal shut-down with the ignition key the humming noise you hear is the LCV stepping motor closing & reopening to cold start position. If you review the Warrior wiring diagram, the ECU fuse Item 70 is not switched. It is directly connected to the battery positive. This fuse operates the LCV and not the ECU.... and yes, i know, it branches to the ECU to do the above
For all the Naysayers with the LCV you can try to prove me wrong by pulling fuse No. 8 (shown below) that should be Labeled LCV fuse ;)
  • You'll want to warm your bike up 1st before doing this test. After removing the fuse, and restarting the bike, you'll see that the engine will start and stay at a high idle and upon shut-down the humming noise will not be present. Before reinstalling the fuse apply some Dielectric silicone lube to the blades and clean out the fuse holder with some contact cleaner & compressed air.

The LCV (linear control valve-for enrichment cycle) {I believe to be} a 4-pole stepping motor that operates open loop w/o any feedback. ECU Pins 21, 22, 43 & 44 increment the valve via the CPU {and driver}. Negative polarity does the task {open & close depending upon the sequence (21-44 or 44-21)} at the pins and positive polarity is from the aforementioned fuse and referenced thread.

Taken from the YFSM and corrected by this writer: Page 1-29 for the specifics of the operation and corrected 1.5° movements of the LCV..

Because the LCV operates on open loop, Yamaha engineers wrote the logic to always HOME (close & reopen for cold start) the valve during normal shut-downs to assure that it is repositioned for next cold start - Hence the humming noise and also why it isn't switched by the ignition key.

I hope this brings clarity to this subject and for the Naysayers, prove me wrong :D

Mike (WD) if you listened to this video and have the exact same lagging humming noise then you didn't remove the LCV :confused:
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