'94 R1100RS battery/alternator light stays on

[psikora]

First off, I apologize for not finding similar results in a search. I must be doing something wrong.

I was riding home last week and noticed my battery light was glowing. I previously added a 12v panel meter which read 13.8v at speed. My friend says it should be at least 14.0. I have a one- or two-year-old Odyssey battery.

My friend suggested checking my multimeter voltage reading with the bike running vs the panel meter. They are the same or no more than 0.1v different.

It looks like this has the upgraded alternator pulleys as the top one is steel, not aluminum, and the bottom one doesn't have the three spot welds on it. I can turn the belt mid-span more than 90 degrees and there is more than a 1/4" deflection. Can self-adjusting mechanisms get hung up?

Before I start removing the tank and a lot of Tupperware to look for ground leads from the alternator for cleaning (did that for main ground leads last year), should I be looking for something else first? Any help would be mucho apreciado.

phil, #09135

 

[dieselyoda]

Check your fuses. Pull them out, look for corrosion, inspect for blown, install and check continuity.

 

[psikora]

Check your fuses. Pull them out, look for corrosion, inspect for blown, install and check continuity.

Will do. Thanks. I was looking to see if there was a fuse for the alternator. Not sure there is. On top of that, the '94s have a beta electrical system. It's not documented anywhere. They're close to later models but the fuses are a little different. Anyway...on to more diagnosing...

 

[m_stock10506]

13.8 volts output from an oilhead alternator doesn’t seem unusual. It sounds like your belt may be loose and slipping. Checking for corroded connections also sounds like a good idea.

 

[gsaddict]

13.8v to 14.0v is the factory setting for the stock regulators in the oilhead alternator.
If this voltage is measured at 2000+ RPM (at the battery)then your system is charging "correctly"

What is strange is that your charge light is on....it would suggest that the blue wire D+ has a ground fault somewhere but then the alternator would not self excite and bring the voltage to 13.8v

 

[dieselyoda]

Check to see if you have brake lights.

Odd?

Just saw the exact problem a few weeks ago. No brake light but everything else was fine except for the charge light on. Bulb pooped.

 

[psikora]

And the winner is...

Check to see if you have brake lights.

Odd?

Just saw the exact problem a few weeks ago. No brake light but everything else was fine except for the charge light on. Bulb pooped.

...fuse #1 which includes the brake lights was blown. This actually leads to a more provocative problem. I had this problem last year but with slightly different symptoms. This fuse would blow intermittently, and I could never recreate it the symptom at home. I could go anywhere from three weeks to three minutes without it blowing again. I'm suspecting a positive lead rubbing somewhere?

To diagnose it I unplugged the front brake light switch and rode for a few months. Nothing blown. Repeated the process for the rear brake switch. Nothing blown. Been riding for a month now and with this recurrence, only my mind is blown. Maybe I should just keep feeding the habit? (I did that with front brake pads on a 1980 Accord for awhile (10K miles per set of pads on one side even after rebuilding the caliper) until I took the no-prisoners approach, replaced the flexible hose, cut it up into 1" pieces, and discovered an internal collapse on the inner section of the rubber hose, right where it gets clamped to the body).

The prior owner has installed a second taillight bulb. I added an LED bar. It's been in this configuration for a long time so I don't suspect a load problem. Prolly not a good idea to replace the 15 amp fuse with a 20 and see what happens. I believe I've checked for grounding where I could. Oh well...

Thanks, dieselyoda. Any other thoughts greatly received.

 

[pauls1150]

An additional tail and/or brake light, plus LEDs, shouldn't blow the fuse - I've got a similar setup with no issues (except for throwing a code on a GS-911, which I ignore).

However, the previous owner's additional wiring would be something to definitely examine in detail...

Fuse #1 has a lot of responsibility besides the brake lights + both brake switches - the tach, fuel level damping unit, and your dash warning lights are on that circuit also, so there are more things to look over. Try to look at these items next time it blows - it's a clue... It may even be useful to pull the bulbs and examine inside the sockets for conductive debris, but that's not common.

 

[dieselyoda]

However, the previous owner's additional wiring would be something to definitely examine in detail...

It may even be useful to pull the bulbs and examine inside the sockets for conductive debris, but that's not common.

 

[roger 04 rt]

...fuse #1 which includes the brake lights was blown. This actually leads to a more provocative problem. I had this problem last year but with slightly different symptoms. This fuse would blow intermittently, and I could never recreate it the symptom at home. I could go anywhere from three weeks to three minutes without it blowing again. I'm suspecting a positive lead rubbing somewhere?

To diagnose it I unplugged the front brake light switch and rode for a few months. Nothing blown. Repeated the process for the rear brake switch. Nothing blown. Been riding for a month now and with this recurrence, only my mind is blown. Maybe I should just keep feeding the habit? (I did that with front brake pads on a 1980 Accord for awhile (10K miles per set of pads on one side even after rebuilding the caliper) until I took the no-prisoners approach, replaced the flexible hose, cut it up into 1" pieces, and discovered an internal collapse on the inner section of the rubber hose, right where it gets clamped to the body).

The prior owner has installed a second taillight bulb. I added an LED bar. It's been in this configuration for a long time so I don't suspect a load problem. Prolly not a good idea to replace the 15 amp fuse with a 20 and see what happens. I believe I've checked for grounding where I could. Oh well...

Thanks, dieselyoda. Any other thoughts greatly received.

Put a dc ammeter in place of the fuse. Watch the current while you operate all the controls. If the current is always well below the fuse’s rating, you’ve likely got an intermittent short somewhere. If the current is near the fuse’s rating then you have too many loads and likely the fuse is failing from thermal fatigue.

If you have an intermittent short try moving the wiring harness while the ammeter is installed.

Your ammeter should have a fuse in it which may blow so have a spare.

 

[dieselyoda]

Put a dc ammeter in place of the fuse. Watch the current while you operate all the controls. If the current is always well below the fuse’s rating, you’ve likely got an intermittent short somewhere. If the current is near the fuse’s rating then you have too many loads and likely the fuse is failing from thermal fatigue.

If you have an intermittent short try moving the wiring harness while the ammeter is installed.

Your ammeter should have a fuse in it which may blow so have a spare.

Or, get an old fashioned boy-scout compass, fire up the bike and walk the perimeter of the bike. The "N" pole will point to the strongest current draw.

 

[roger 04 rt]

Funny, but I like it. Have you used that on something as small and dense as a motorcycle?

To work I guess you’d have to remove the headlight (or load relay because it’s always on with the key on, possibly the Motronic too.

 

[Motorrader]

Motorrader

Check to see if you have brake lights.

Odd?

Just saw the exact problem a few weeks ago. No brake light but everything else was fine except for the charge light on. Bulb pooped.

Thanks a million....you saved ME a lot of diagnostic time! brake-light burned out...

 

[dieselyoda]

Yeah, starting simple and sometimes re-starting at simple avoids lengthy spreadsheets, 1000 words of complexity or the worst, throwing parts at the problem.

Just wish my guess would embrace, start at the battery, work you way from the black cable and then go back to the battery then work the red cable.