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I've had an odd thing happen with one of my tail lights in the last few weeks. While on a recent road trip, I stalled my bike while crawling in stop and go traffic. I tried restarting and the bike hiccuped... a second try at restarting was attempted and the bike started right up. Immediately upon starting my right tail light went out, as evidenced by the dash warning indicator coming on and confirmed by my riding buddy who was behind me. At first I just thought, "crap!... out on the road for 3 days with little chance of replacing it until I get home". After we passed the accident that was stalling traffic we pulled over to stretch our legs and for me to get the cramp out of my left hand from feathering the clutch for 45 minutes straight! Once we restarted, the warning indicator went off and my buddy confirmed that my tail light was back on. No more problems the rest of the trip.

All lights have been burning fine for the last 4 weeks without any issues until yesterday when I started the bike to head out for a ride. The ambient temp was cold (28 F) and the bike had been sitting without starting for about a week - I let go of the started button a tad soon and the engine failed to start right up. I gave it a second try and it started up as normal, but the tail light indicator came on! Thinking back to the road trip outage and the fact that it seemed to be correlated with the failed start...I turned the bike off and restarted. The warning indicator was off and the tail light lit!

Anyone have a similar experience or have any ideas?

Lawrence
 

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Voltage spikes and computers,yikes. I use to work on vessels with electronic controls for the propulsion plants, some are rather complicated with banks of PLC's, computers, SCR systems, cyclo converters and other such devices producing much smoke and heartache. One vendor use to refer to problems such as yours as FM. .....f..king magic. :) This leads to the conversation to always have a diode protection circuit on the trigger coil of any relay you add to your bike. This will keep the field collapse of the relay coil from spiking the circuit (think spark plug coil) by letting this induced voltage bleed down.
Totally not not part of your problem but very good explanation of this is:
http://www.autoshop101.com/forms/hweb2.pdf
I suspect in the circuits of the BMW computer are little protection thingies for this kind of event. But the hit of the starter really changes the battery circuit voltage and it may have been a little iffy due to that long traffic jam also.
 

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Discussion Starter #3
beech said:
Voltage spikes and computers,yikes. I use to work on vessels with electronic controls for the propulsion plants, some are rather complicated with banks of PLC's, computers, SCR systems, cyclo converters and other such devices producing much smoke and heartache. One vendor use to refer to problems such as yours as FM. .....f..king magic. :) This leads to the conversation to always have a diode protection circuit on the trigger coil of any relay you add to your bike. This will keep the field collapse of the relay coil from spiking the circuit (think spark plug coil) by letting this induced voltage bleed down.
Totally not not part of your problem but very good explanation of this is:
http://www.autoshop101.com/forms/hweb2.pdf
I suspect in the circuits of the BMW computer are little protection thingies for this kind of event. But the hit of the starter really changes the battery circuit voltage and it may have been a little iffy due to that long traffic jam also.
Thanks Beech!

I was just about to chalk it up to demons!!

:bmw:
 

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Is this related to it being CANbus as opposed to a fused electrical system? I love the FM.

beech said:
Voltage spikes and computers,yikes. I use to work on vessels with electronic controls for the propulsion plants, some are rather complicated with banks of PLC's, computers, SCR systems, cyclo converters and other such devices producing much smoke and heartache. One vendor use to refer to problems such as yours as FM. .....f..king magic. :) This leads to the conversation to always have a diode protection circuit on the trigger coil of any relay you add to your bike. This will keep the field collapse of the relay coil from spiking the circuit (think spark plug coil) by letting this induced voltage bleed down.
Totally not not part of your problem but very good explanation of this is:
http://www.autoshop101.com/forms/hweb2.pdf
I suspect in the circuits of the BMW computer are little protection thingies for this kind of event. But the hit of the starter really changes the battery circuit voltage and it may have been a little iffy due to that long traffic jam also.
 

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Lawrence_D said:
Thanks Beech!

I was just about to chalk it up to demons!!

:bmw:
I dont know about Demons, But I think they are called Gremlins? :rotf:
 

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I had a very similar occurrence. Riding with two buddies, I stopped for gas. When starting after gassing up, I noticed the warning indicator. I thought it was a bulb, but I wasn't sure exactly what (I can't always see the icons clearly without stopping). We hit a long section of twistys, then later at a stop, one of the buddies asked me if my brake light was working. I checked -- it wasn't. He said he couldn't understand how I was attacking the corners that aggressively without hitting the brakes.

When I started back up everything was working okay and has been ever since.

Yes, yes, yes... GREMLINs are real!
 

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Similar event. Started the bike, put it gear - kickstand still down - engine stopped. Flipped up the kickstand and started it up and got a "headlight out" indicator. Indeed, the headlight was off. Went about my way, fretting, etc. The next time I started the bike "cleanly" using the key, waiting for things to settle, everything was OK - lights working, no fault indicators. I have repeated this sort of thing - if the bike stops (stalling from the cold for example) and you restart it without going to key off, key on, pause, you might get a fault. It isn't the CAN BUS per se, it is the control module for the lights and signals. (The CAN BUS is how the three modules in the bike communicate - not directly involved with the items the module controls.) The module gets some sort of confusing transient and shuts down the light or signal thinking there is a fault - a fault is either too little current (must be burned out) or too much current (a short - remember - no fuses). A clean power-on cycle will clear it.
 

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Hi Lawrence,
I just watched your Youtube video. When you made that right hand turn at the stop sign in Stull you were about ten minutes or so from my place. Anyway, next time you want some good footage go up to Lake Perry and cross the dam westbound, taking a hard right turn just at the west end of the dam. Be careful this time of year though. Lots of shaded road and hard twisties. Take a second right at the T intersection and you'll come out on Highway 237 north of Highway 24 and west of Perry. It's a short run but very enjoyable.
 

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Discussion Starter #10
deanwoolsey said:
Hi Lawrence,
I just watched your Youtube video. When you made that right hand turn at the stop sign in Stull you were about ten minutes or so from my place. Anyway, next time you want some good footage go up to Lake Perry and cross the dam westbound, taking a hard right turn just at the west end of the dam. Be careful this time of year though. Lots of shaded road and hard twisties. Take a second right at the T intersection and you'll come out on Highway 237 north of Highway 24 and west of Perry. It's a short run but very enjoyable.
Hi Dean,
Nice to meet you and thanks for the tip. I ride up that way, but I don't think I have gone exactly the way you say. My best riding buddy lives on Jefferson Road, beautiful house up on a east side bluff has a sign "Crow's Nest" by their mailbox. I also hunt up in the Valley Falls area, so I am all over those roads up around Highways 4 and 16. I'll check out your ride!

Thanks,

Lawrence
 

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From what I've read about the CAN bus system, if the bike failed to start the system probably didn't complete a check routine and stored the taillight as a fault and then disabled power to that item. Pushing the starter button doesn't clear the error but off/on does.
 

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Similar things have happened to me, also related to aborted starts (hiccups, failed compression starts on hills, or letting off the start button before the engine catches). Once the "major fail" warning light came on, disappeared when I turned off the ignition, let it sit a few seconds, then went through the normal start procedure. Another time I was riding along and the factory radio started fading quieter and quieter, then went dead (audio Gremlins). Took the next offramp, shut off the ignition, and then all was well when it came back up. A third time the light bulb warning light came on, again the reboot fixed it.

I liken it to using Microsoft software - anyone else remember the "blue screen of death"? Sometimes ya just gotta "<Ctl> <Alt><Del>" the system to get it to behave properly. Part of the "charm" of the German engineering (like changing headlight bulbs ...) If we wanted boring we'd be riding Hondas.

JayJay (who has owned plenty of boring bikes)
 
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