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Discussion Starter #1
Recently picked up this bike ('99 ST4). Had the 30K-mile service done, bike running beautifully. Went on a long ride today, everything was great (after about 120 miles) until we stopped for a minute. I tried to start the bike up - nothing. LCD display didn't even come on most times I turned the ignition on, though sometimes it did - but not normally. All the idiot lights were very weak, like the battery was completely discharged. Tried to bump-start it - was able to get it to fire up briefly, but the gauges were still acting funny and the bike died when I shifted gears. Got it home (flatbed tow) and hooked up a voltmeter to the battery-tender lead - 12.6 to 13.2 V! I was expecting 8 or 9. Even with that, still can't get the gauges and lights to turn on normally - very weak, like the battery is dead. Fluid level in the battery looks OK. Looking for a diagnosis here:

Cell failure in the battery- short?
Alternator/voltage regulator/stator?
Bad ground all of a sudden?

Anyone have this happen and have an idea what it might be? I'd hate to pull the whole damn bike apart if it's something simple. Jeezus, just getting the middle fairing panel off is a lot more complicated than it should be!

Thanks
Bob
 

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I recently bought a 98 ST2 with some electrical issues. In my case, it turned out to be the wiring going into the battery. My mechanic took apart the wires/peeled back the housing and found some of it had corroded over time combined with being affected by heat. My bike has 20,000 miles on it.

My symptoms were different. I could be riding and lose all power. If I reached in the right side vent area by the batter and giggle the wires I could get power hit or miss.

So far, 1,500 miles later problem seems to be solved. Worth looking at those wires.

Just a thought.

good luck.
 

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Discussion Starter #3
Thanks...I'm beginning to suspect it might be a bad connection. I'll pull things apart tomorrow and take a good look.
 

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Could be the igntion relay. It is the one under the LH upper fairing beside the flasher relay. It energises when you turn the key to ON and nearly all of the main fuses are fed by it. Bad internal contacts will give similar symptoms to those you describe.
 

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Discussion Starter #5
Could be the igntion relay. It is the one under the LH upper fairing beside the flasher relay. It energises when you turn the key to ON and nearly all of the main fuses are fed by it. Bad internal contacts will give similar symptoms to those you describe.
Thanks, Derek...one more thing to check out. Is there an easy way to test it with a volmeter?
 

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Check the batttery terminals and make sure all the connections to the battery are snug.
 

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Discussion Starter #7
All fixed, I hope. I finally got all the fairing panels off, took the battery out and had it load-tested. Though the battery registered 12.6 V at rest, it went to near zero with a load. Put in a new battery, bike fired right up, and the charging system appears OK; voltage at the battery goes up to 13.4 or so at 3500 rpm. :)
 
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