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Discussion Starter #1
Hi All,
hoping someone can shed some "light" on this trouble light. So I recently purchased a 2008 K1200S and the previous owner had installed LED bulbs everywhere. Both LampF! and LampR! troubles were displayed. So once I took possesion I decided to just change evtrything back to factory lamps. Bought lots of lamps and changed every single bulb on the bike. The LampF! cleared no issue but the LampR! is still on. I took everything apart, checked every connection, changed all the rear bulbs again, broke down and bought a GS-911 and the motoscan tool, and cleared every error code known to man on the unit. Still have this LampR!. Read some more and went riding for 2 hours, hoping the CANBUS would re-learn that the lamp was good. Nothing still have this failure lamp. So I am at a hai-pulling state currently. Wondering if anyone has any suggestions? My next approach will be to take it to a dealer and let them figure it out, which I don't really want to do and pay lots of cash to have someone probably do something simple.
Thanks,
SJ
 

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LAMP faults in the rear of the bike are typically tied to brake/running light and turn signals only. Not sure what else would cause an issue. I'm curious to hear if anyone has any insights on this as well. FWIW, I took my K12S to the dealer to have them reset my service reminder and clear the codes (no GS-911 here), they only charged me $67 so can't imagine they'd charge you a bunch more. That said, I'm sure someone here can help.
 

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Does the runninglight work in the rear, does brakelight work on both the lever and fott brake?

There are 3 wires for the rear light, 1 ground/negative, usually brown. Then 1 12v+ for the running light and 1 12v+ for the brakelight, check that power comes to both the 12v + wires.
The runninglight and brakelight is a dual filementbulb, 21/5w.
 

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Discussion Starter #4
Well when I was confirming the tail lights and turn signals, the turn signals work no issues, I even took them out and turned them around (read on the internet someone who had done that) the tail and brake light function as follows: Tail light turns on right away with key turned on. The tail light goes to full brilliance when the front or rear brake is applied. The brake light part of the lamp does not turn on. Everything I have read leads me to believe the CANBUS turns off the circuit until the light is corrected. I suspect the LED lamps installed by the PO was th original cause, but perhaps I am mistaken on this.
I totally disassembled the lamp socket, cleaned every connection, put it all back together and still nothing. If I could determine where the wires lead to I could possibly check the wiring all the way to the black CANBUS box to see if there is a break somewhere along the way. I ca't see anywhere where the wiring harness has been frayed or taken apart for a quick fix, it all appears like factory installed. Thus the reason I am somewhat stumped. Not sure if the CANBUS needs time to re-learn the circuit, or whether there is something I am missing. I am an electrician by trade so troubleshooting this should be easy. Not sure where to look next, so any ideas or if someone knows where to follow the wires end to end, this would be helpful. I do not have a wiring diagram or I could follow the wiring from the diagram.
 

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Things are working as bmw intended, the runninglight shines harder because there is a problem with the brakelight. This is controlled by the abs computer. A safetyfeature to ensure you always have some form of brakelight.

There is no power coming to the brakelight wire or there is no contact in the lightbulb holder. Possibly a broken wire or a short on this wire. Need to check this over.

The canbus turns power off if there is a short on the wire and it turns power back on when the problem is sorted and ignition turned off/on again. Do not need to clear codes, they only get stored in the memory but does not cause anything.
 

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Discussion Starter #7
Got the download but it is unreadable. I will go back and trace the wiring as much as possible. As I indicated in my previous post, I did follow the wiring harness as much as possible. I am going to go back and unplug sections of the harness and read continuity to see if I can find a break somewhere. Will keep you posted.
 

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Discussion Starter #14
Ok so after lots of investigation, here is what I have found, repaired and traced. The voltage going to the tail light socket appears on the brake light circuit. About 2.5 volts with key on and 12.3 volts with either front or rear brake applied. There is no power going to the running light portion of the socket. I traced this wire all the way to the ZFE box and it has continuity. I also checked continuity through the lamp to ground and it appears fine, less than .04 ohms from the ZFE connector to ground through the lamp. I did find when taking the wiring harness all apart a license plate lamp taped and tucked way up under the seat, replaced this lamp as well. Not sure if the ZFE box may be faulty? The license plate lamp was burnt out so is it possible it just takes a few rides to reset the ZFE into a realization state that the circuit is working again?
 

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It doesent need a few rides, ignition off and on 1 time. Could be someone has changed settings in the zfe, there is a setting, kl-58 that can be set to led, and taillight set to led, get someone that has motoscan to check it for you.
 

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The part about you reading a low voltage is the safety feature i was talking about. The computer puts a low voltage forward to the brakelight so that you will have a runninglight because the usual runninglight is not working. A bad zfe, highly unlikely, the problem is most likely in the settings or in the wires, connectors or swtiches.
 

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Discussion Starter #17
The programming on the ZFE was the issue. Found th ecoding for the ZFE for LED lamps per the kl-58 setting and bingo, trouble code went away. So in hindsight I think the whole issue stemmed from the license plate lamp that was taped off way up under the tailpiece, It was burnt out, so after I changed all LED lamps to regular, ripped everything apart, tested put is all back together with a head scratch, followed the programming instructions above, I am now thinking if I would have found the license plate lamp right away the problem probably would have disappeared. Well trouble is gone, and all works as it should, thank you to all who offered assistance very much appreciated.
 

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You are encountering a can buss error. When you add lamps either hid or led to a bike that has a buss type network electrical system, the characteristics such as voltage drop, amps across any one of them is expected to conform to certain values. The led or hid use much lower values as they are much more efficient than halogens. Some systems have provision to go in and actually change the type of bulbs like on my mercedes slk where you select from halogen, hid or led.
Depending on the year of your K12 this may exist as an option or not! Fortunately and unlike my mercedes, the lights work on your K and all you get is the stupid lamp warning. On my car the lights switch on/off constantly plus you get the warnings!
But hey, now you have a local area network on your bike and you have saved a ¼ lb of copper wiring in the harness! Whoop di doo!
Forgot to add that I upgraded my 2006 K12 to hid's many years ago and have lived with the warning light! I happened to take my bike in to a dealer 2 weeks ago for a recall and they said mine didn't have provision for led/hid's.

Ross
BTW i'm a bmw car mechanic & electrical engineer, both retired...
 
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