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Discussion Starter #1
My 2000 F4 750 has been in the workshop for a long while. When I came to fire it up after a long winter, there was little to no sign of life. Battery was full-charged, but nothing on the dash. (There was a momentary blink of warning lights as I turned the key, but nothing more)
All was well when I rattled the 3 relays on the Left-hand side. Dash came to life, Rev counter swept, bike started fine.
Before I get stupid and replace *every* relay, does anyone have a suggestion as to which relay it’s likely to be?
PS, when I first bought it, the charge warning light would flicker once the revs rose. Now it doesn’t. Might this help diagnosis?
Thanks in advance.
 

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The relays to the left of the headlight are the Hi and Lo beam relays.

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My guess here would be that you rattled the dash enough to shake the multi-pin connector on the back of the dash. Were it me, I'd remove the dash, disconnect the multi-pin connection, clean it and then reassemble.
 

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Discussion Starter #4
The relays I “disturbed” are the three to the left of the bike, below the tank, beside the alternator. One is the starter relay with a 40a fuse, which dipple666 suggested I check. I’ve reseated this the centre one, I gather, is the flasher relay (more later) and the last, most forward one is - I dunno.
Should I bother replacing any or all of these? The starter one is cheap enough, but is it vulnerable to failure? Could the front-most one cause the lack of electrical power to the dash etc.?
 

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Discussion Starter #5
I’ve found a can of worms here! Lots of electrical tape around the cables leading to the relays above. On picking this off, I found:
A bodge on the indicator relay, where the previous owner has added a resister or something. That relay will be replaced, as it appears to have been filled/sealed with some white, powdery substance. Once I have both front and rear indicators fitted I can check whether the additional component is needed.

On the front-most relay, someone appears to have attempted to bridge the blue and the white wires with a small electrical component. Tiny, black, possibly a diode? The rigid wires of this are broken, so it’s not serving any purpose.

Is this some superduper enhancement i’m not aware of? If not, i’ll clip it off! The 5-way connector for that relay is in less-than-first class condition. Any readily-available replacements?
 

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I know my Senna has a single diode that has been there from the factory.

I do remember replacing it years ago, Donsy solved the fault from the other side of the world, but I can't remember the root cause.

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Discussion Starter #11

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Found this thread from a few years back.

It seems there should be a diode there. Mine’s inoperative, yet all seems to work. The current diode attachment/soldering seems very amateurish, not OEM at all. I wonder what it does? If it works, perhaps I should leave well alone?

https://www.mvagusta.net/forum/20-maintenance-tech-issues-all-4-cyl-models/83186-reverse-polarity-help.html
That looks like the problem I had.

Maybe the previous owner has reversed the polarity at some point, they wouldn't have been the first to put the battery on wrong.

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The Three Relays....

...in that bracket are the START SOLENOID, THE INTERMITTENCY (Turn Signals) and the GENERAL FEED RELAY.

That GENERAL FEED RELAY provide power to a lot of the bike and, yes, it should have the DIODE, and yes, you should replace the diode.

1.jpg

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Now go to Donsy's website: Team Double 3 Racing | MV Agusta and download your manuals for free. Give Dons a virtual hug and don't guess about your bike.
 

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Ed, that is the GENERAL FEED RELAY....the first one in the bank of three on the left side of the bike...beside the START SOLENOID.
 

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Now, about the FLASHER RELAY: The Intermittency....

The original owner may have done some modifications to turns signals. Many folks add LED signals and that requires the installation of resistance to make up for the loss when incandescent bulbs are replaced by LED bulbs.

See what your turn signals are.

Also, and I know this may be hard to believe, but all of this has been discussed many times before in excruciating detail in this very forum.

Please learn to use the ADVANCED SEARCH FUNCTION....it will save you hours of time.
 

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Discussion Starter #16
Yup. I know about the flasher resistor concept. I fitted power resistors to my NSR to cope, thanks. I *simply* noted that the bodger had done some work on the flasher relay, and that it would be replaced, too!
Thanks anyway for your advice that I should renew the diode on the general relay. I’ll do a better job of soldering too. Interesting that everything works without it. Presumably it’s to prevent electrical flow should the battery polarity be incorrect.
 
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