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Thread: Flashing charge light - '03 K1200RS

  1. #1
    Kein Nasebohrer RBEmerson's Avatar
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    Flashing charge light - '03 K1200RS

    Of late, the charge light comes on and stays on after starting the engine. The intensity varies, but in the end, it's on. Until I twist the engine up to about 2100 - 2500. The light goes out and stays out. I checked the battery this afternoon and found 12.9V with the key off; with the engine idling, 12.1V(!). This is Not Good. Checking the wiring diagram, there really isn't very much to get worked up about. There's blue wire from the alternator to the charge light and a red wire to the battery (and also off to I forget which black box) - "Nothing to see here, folks, move along."

    I'm beginning to suspect the alternator is going but maybe it's something else? Before I BMW (Break My Wallet) with the dealer, to troubleshoot and R&R expensive bits and pieces, does anyone have any suggestions about what's going on here?
    Don't let your bike go anywhere your brain hasn't already been five seconds ago...

  2. #2
    Registered User WalterK75's Avatar
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    I don't know if they have it, but check to see if there is a voltage regulator on alternator that uses brushes. If so, it may be the brushes are worn and not making a good contact. Had this happen on a 1991 K75 recently.
    Walter

    All government, of course, is against liberty.
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  3. #3
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    From BMW: 12 31 1 739 365 VOLTAGE REGULATOR $143.57



    From Euromotoelectrics: http://www.euromotoelectrics.com/category-s/851.htm

    Original Equipment NEW BOSCH internal voltage regulator. Easily replaced on all BOSCH alternators on BMW K models. Simply remove screws and replace with new. Save $ hundreds of dollars over new alternator !

    Internal Voltage Regulator - BMW R Oilhead & K; 12 31 1 739 365 / Bosch
    BMW List Price $140.63
    Our Price $39.00
    You save $101.63!

    Part #: BOALT-Reg365


    Internal Voltage Regulator for BOSCH internal fan alternators use on R oilheads and later K Models
    Drops into the top of the rear of the alternator

    Vehicle Manufacturer: BMW

    Application: Fits ALL R850 , R1100 1993-2007 & K w/ internal fan alternator

    Make/Model: BMW : R850, R1100, R1150, R1200, K75, K1100

    Model Years: 1984 to 2007

    Vehicle Mfg. Part #: 12 31 1 739 365

    Power Rating: 14.2 Volts, 50 and 60 amps

    Brand: EnDuraLast Brand

    CONTACT US:
    2505 W 2nd Ave
    Unit # 14
    Denver, CO 80219 USA
    (303) 526-0901 info@euromotoelectrics.com



    It is a module that combines the brushes and voltage regulator. Under Make/Model Euromotoelectrics SHOULD also say K1200. It's just a typo. It's the right part #. It is for BOTH the 50 Amp AND the 60 Amp.


    Last edited by 98lee; 08-12-2013 at 02:46 PM.
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    Lee Fulton Forum Moderator
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  4. #4
    Kein Nasebohrer RBEmerson's Avatar
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    Interesting... looking at Clymer's charging circuit testing procedures, excess voltage, as engine speed climbs, is their "regulator is toast" flag. Which makes sense. Regulators work by varying the voltage to the field: lower voltage, lower output and vice versa. My problem is the reverse - low voltage until something magically kicks things loose at around 2K RPM. But I do wonder about the brush. The bike has 33K on it, which should mean the brush should still have tons of room to accept wear. NTL, I'll look into this. TNX!
    Don't let your bike go anywhere your brain hasn't already been five seconds ago...

  5. #5
    Registered User WalterK75's Avatar
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    Voltage regulater is made by Bosch. If you need one, get it via a parts supplier or Bosch. Why? I got one via an auto parts supplier and it was $100 less than the one from BMW. Same part. You all know this scenario.
    Walter

    All government, of course, is against liberty.
    H. L. Mencken

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    Sorry, I guess I didn't register the "Until I twist the engine up to about 2100 - 2500. The light goes out and stays out." part. What's the voltage after that?

    The light may glow (particularly with the heated grips activated) because some resistance has developed in the connections on the (gn sw) side of the circuit that slightly lowers the circuit voltage, so that a minor voltage difference occurs. If the light goes out after you bring the RPMs up once, and the voltage is good, I wouldn't worry about it, especially at such low mileage. The brushes should last 80k miles +.


    LONG MAY YOUR BRICK FLY!

    Ride Safe, Ride Far, Ride Often

    Lee Fulton Forum Moderator
    3 Marakesh Red K75Ss
    Mine, Hers, Spare

  7. #7
    NC Piedmont Rider ncstephen's Avatar
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    RB

    Mine has done this same behavior for the last 70,000+ miles. I first noticed the failure in this trait on cold mornings when I would start it and let it idle (20-30F) and then find it had died (never having sped the motor up to the point you mentioned) and then the cold weakened battery unable to restart the bike. I discovered the function of this trait after leaving the house one night and started then very easy pulled off. Once speeding up I suddenly saw the lights brighten. Paid attention to this and realize that yes, on my 03 K-RS the charging circuit seems come alive around the first time rpms cross 2300 rpms. I typically watch the dash at start up and notice the neutral and high beam indicator get a few percent brighter when this happens. All is good at idle then. My charging "light" has become intermittent over the years of not illuminating all the time at switch on/start up. Not a lot of time has been spent on the whys of that.

    My alternator did fail about 25,000 miles ago. When riding home from work one evening I noticed the dash lights a bit dim and the GPS began to act flacky. 10 more miles home at that point. Turned everything off that I could. 8 miles later getting off the interstate, the light finally showed a slight dull red glow that varied a little with rpms but didn't go out. The dull glow didn't show up until the battery was just keeping the bike running. 2 more miles home. Last 1/2 mile the tach stopped working. Pulling in the drive it was running rough and stalled while parking it.

    As this was repaired, the intermittent behavior of the "light" really didn't change much nor the aspect of charging after the initial crossing 2300 rpms.

    Some days after start and the bike returning to idle the charging light will faintly glow but once rpms cross that threshold you mentioned, all is golden again.

    The battery stays fully charged, I know of this unique charging behavior at first start, everything works well and so no real time and $ has been spent chasing this little quirk.

    Hope this helps you with your thoughts on whether to chase this little unique behavior. I have had no reliability problems associated with this other than starting the bike on a low battery (due to cold) and then letting it idle without crossing the charging threshold.

    NCS
    03 K 1200RS (Black is Best)
    03 Honda RC51
    74 Honda CB750 K4

  8. #8
    Kein Nasebohrer RBEmerson's Avatar
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    Quote Originally Posted by 98lee View Post
    Sorry, I guess I didn't register the "Until I twist the engine up to about 2100 - 2500. The light goes out and stays out." part. What's the voltage after that?

    The light may glow (particularly with the heated grips activated) because some resistance has developed in the connections on the (gn sw) side of the circuit that slightly lowers the circuit voltage, so that a minor voltage difference occurs. If the light goes out after you bring the RPMs up once, and the voltage is good, I wouldn't worry about it, especially at such low mileage. The brushes should last 80k miles +.[...]
    Well, y'know, on one hand, everything does look good other than this little annoyance. OTOH, everything was just fine until this spring. Something has changed and having an unexected change is rarely a good thing.
    Don't let your bike go anywhere your brain hasn't already been five seconds ago...

  9. #9
    Kein Nasebohrer RBEmerson's Avatar
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    Quote Originally Posted by ncstephen View Post
    RB
    Mine has done this same behavior for the last 70,000+ miles. I first noticed the failure in this trait on cold mornings when I would start it and let it idle (20-30F) and then find it had died (never having sped the motor up to the point you mentioned) and then the cold weakened battery unable to restart the bike. I discovered the function of this trait after leaving the house one night and started then very easy pulled off. Once speeding up I suddenly saw the lights brighten. Paid attention to this and realize that yes, on my 03 K-RS the charging circuit seems come alive around the first time rpms cross 2300 rpms. I typically watch the dash at start up and notice the neutral and high beam indicator get a few percent brighter when this happens. All is good at idle then. My charging "light" has become intermittent over the years of not illuminating all the time at switch on/start up. Not a lot of time has been spent on the whys of that.
    Yesterday I spend some time behind the clocks, after installing LED's a couple of days back. Initially it was to sort out two problems. An LED in the neutral light needs a load resistor across the leads. Without it, the neutral light stays on all the time when the engine's running. It's dimmer when in gear, but bright when either the clutch is pulled in (interlock switch changes state) or in neutral (well, there's a stunner). The other problem was very no-tech: ambler LED behind a red-filtered idiot light. Oops. Anyway... I cleaned up the wiring terminals for the speedo and tach, particularly the brown grounds "just in case". The light still flickers. At least the clocks now have shiny connections.

    My alternator did fail about 25,000 miles ago. When riding home from work one evening I noticed the dash lights a bit dim and the GPS began to act flacky. 10 more miles home at that point. Turned everything off that I could. 8 miles later getting off the interstate, the light finally showed a slight dull red glow that varied a little with rpms but didn't go out. The dull glow didn't show up until the battery was just keeping the bike running. 2 more miles home. Last 1/2 mile the tach stopped working. Pulling in the drive it was running rough and stalled while parking it.

    As this was repaired, the intermittent behavior of the "light" really didn't change much nor the aspect of charging after the initial crossing 2300 rpms.

    Some days after start and the bike returning to idle the charging light will faintly glow but once rpms cross that threshold you mentioned, all is golden again.

    The battery stays fully charged, I know of this unique charging behavior at first start, everything works well and so no real time and $ has been spent chasing this little quirk.

    Hope this helps you with your thoughts on whether to chase this little unique behavior. I have had no reliability problems associated with this other than starting the bike on a low battery (due to cold) and then letting it idle without crossing the charging threshold.

    NCS
    Now that's really odd. It would seem reasonable that changing the alternator would mean most of the usual suspects, that would set the light flashing, would have been worked over in pulling battery and digging into the alternator. How very, very odd.

    There are self-exciting alternators (a little helper coil supplies enough voltage to trigger the main coils into doing their job) and externally excited (gotta have a working battery) alternators. Either way, at low speeds, things are just about breaking even. So with a heavy load (heaters, lights, GPS, etc.), it's not unreasonable to get a hint of low voltage at idle. In my case, though, even turning the grip heaters up doesn't trigger a thing once the magic 2300 RPM threshold is crossed.
    Don't let your bike go anywhere your brain hasn't already been five seconds ago...

  10. #10
    Kein Nasebohrer RBEmerson's Avatar
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    The alternator was, in fact, toast. Zero output at anything close to idle. Getting to the alternator is ugly. The sub-frame has to be swung up to get to it. Not a cheap repair.
    Don't let your bike go anywhere your brain hasn't already been five seconds ago...

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