dim lights on yamaha

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Patrick Boehm - 20 Sep 2004 02:13 GMT

My lights dim somewhat when idling or signaling and then brighten up when I
increase rpm's. Would this be a bad regulator or a bad alternator? Thanks.

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Patrick Boehm - 20 Sep 2004 02:40 GMT

sorry about the double post

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Audrey Zoritch - 20 Sep 2004 21:46 GMT

If the dimming is slight, it only happens at idle (low RPM) and is
consistent (the light doesn't flash on and off) it may not be a problem at
all. I've had bikes that have had those symptoms and have had no problems.
The only real way to tell is, as "someone" responded, by the use of a VTVM
and a tech manual.

If the bike doesn't have a high output generator/alternator, the lights will
dim, at idle, because the RPMs are not high enough for the
generator/alternator to put out maximum voltage.

Ride safe
Serge

> My lights dim somewhat when idling or signaling and then brighten up when I
> increase rpm's. Would this be a bad regulator or a bad alternator? Thanks.

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Patrick Boehm - 20 Sep 2004 23:26 GMT

thanks for the info, got to checking things out yesterday, and lo and behold
a ground wire from the engine to frame had fallen off, bolt jiggled out I
suppose, so I got that all connected, shined up the brushes on the
alternator, and today we're much better! I am bidding on a used regulator on
eBay, just in case, to see if that helps. Thanks again.

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repairco - 20 Sep 2004 23:18 GMT

> My lights dim somewhat when idling or signaling and then brighten up when
> I increase rpm's. Would this be a bad regulator or a bad alternator?
> Thanks.

You may have the idle set too low or have too much power draw if you have
extra lighting installed.

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Khutter - 21 Sep 2004 13:45 GMT

> My lights dim somewhat when idling or signaling and then brighten up when
> I increase rpm's. Would this be a bad regulator or a bad alternator?
> Thanks.

Forgive me if this is a repeat post but I thought I posted yesterday.

It could be as simple as the idle set too low or if you have added lights,
too much load. In another post someone suggested a bad ground---I would
start at the battery and go from there. If it is 'none of the above' about
the only recourse left would be hitting all the test points with a good volt
meter to troubleshoot it with the manual. Sorry there isn't a 'quick and
dirty' answer/solution.
Just take your time and be patient. I have worked the electrical trade for
almost 20 years and the electrical system on my bikes has caused me more
grief than almost any industrial application! Patience is the key!

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Motorcycle Forum / General / Yamaha / September 2004

dim lights on yamaha