K12RS balky left-turn switch (what's the most common cause?) - K-Bikes.com - Excellence in Motion
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post #1 of 17 (permalink) Old May 15th, 2008, 12:25 am Thread Starter
 
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K12RS balky left-turn switch (what's the most common cause?)

My 99 K1200RS left-turn switch seems to be balky. Every night, it's working and every morning, it doesn't work for about ten or fifteen minutes. Then it works fine.

I yank and tug on the wires and it doesn't seem to be loose wires. The yellow turn-signal bulbs and green dash light all work fine 'cuz the 4-way flashers always work.

So, I suspect the left grip switch.

Is this something that commonly fails?
Do you think taking it apart will show me what the problem is?

Does anyone else have/had this problem?

Any suggestions for a cure?
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post #2 of 17 (permalink) Old May 15th, 2008, 2:23 pm
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Looks dirty.
Not a common problem....suggest taking it apart and looking for loose connection.

'04 GT...Orient Blue...Staintune...Ohlins...Power Commander
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post #3 of 17 (permalink) Old May 15th, 2008, 2:25 pm
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Switch

Mr. D,
You may have to go inside and blow it out, get rid of any crud/road dirt that may be restricting it. There are three screws. One in the back, that you can see from your picture, one in the front (upper) and one on the bottom you can't see. You then have to really work at separating it, it's a bitch. Then there are two little silver head screws on the inside that must come out because they hold the cover on to all the guts. One you can see on the top right and the other in underneath a silver sticker, yes under a sticker. Punch a hole in the sticker to remove it. The very most important detail is whatever kind of funky little screw bit you need to remove the two inner screws make sure you use the exact tool/size, I think it's a torx. I had to go into my 02' RS and play with the cruise control. Be patient and don't rush or horse the thing around, don't force anything. Once inside check the operation and clean it out. Don't use any oil lubricants. I think the only thing that had lube on it is the cruise control On/Off switch, it has a touch of grease. Hope this helps.

Jim S.
* Everyone crashes. Some get back on. Some don't. Some can't.
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post #4 of 17 (permalink) Old May 15th, 2008, 3:35 pm
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Quote:
Originally Posted by donnatello
My 99 K1200RS left-turn switch <snip>

So, I suspect the left grip switch.

Is this something that commonly fails?
Do you think taking it apart will show me what the problem is?

Does anyone else have/had this problem?

Any suggestions for a cure?
I have a 2002 RS that developed this recently. Unfortunately, after dis-asembling the entire left grip... I found... the switch is sealed. It's small, has a little rubber cover. I uncovered it, air sprayed it, then used some 'electrical contact cleaner' spray and found... it didn't help.

Replacement switch assy (you can't buy just the switch) will be between $250 - $385 depending on where you buy it, and whether or not you have cruise control.

Sorry I didn't have better news for you...

Try Beemer Boneyard for a used one. They are GREAT!

"Lord, Be Kind to Me....the Sea is
So Big, and My Boat is SO Small"

2002 K12RS
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post #5 of 17 (permalink) Old May 18th, 2008, 1:42 am Thread Starter
 
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Is there an exploded diagram of the combination switch left assembly?

Quote:
Originally Posted by DaveTheAffable
... the switch is sealed. Replacement switch assy (you can't buy just the switch) will be between $250 - $385
Bummer. I see what you mean from the realoem site:
http://www.realoem.com/bmw/showparts...86&hg=61&fg=25
The "combination switch, left" is a single assembly.

Unfortunately, I couldn't find an exploded diagram of the combination switch left, so this is the best I can do for myself and others to follow with the same needs.

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post #6 of 17 (permalink) Old May 18th, 2008, 10:02 am
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This is from the '04KRS manual(year 2000 is identical). It's not much better that what you already have.
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Bruce C
'04 K1200RS Capri Blue(totaled)
2008 Triumph Sprint ST

Last edited by brucecha; May 18th, 2008 at 10:08 am.
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post #7 of 17 (permalink) Old May 18th, 2008, 3:11 pm
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Before you tear everything apart, did you clean the contacts in the plug connector where the switch wiring goes into the harness?? BMW wiring connectors are a known failure point .
Also most BMW switches completes the circuit to ground to operate whatever the specific switch is supposed to operate.
While looking at an older "K" wiring diagram(I have nothing else to go by), it shows the horn and left turn signal using the same brown wire(to ground) to complete the circuit to make the horn or turn signal operate. I doubt BMW would change this wiring method, after all, they never fixed the "box of rocks" clutch sound in 22 years.
A simple test would be to see if the horn acts up the same way your turn signal switch does. If so, your problem is most likely in the switch wiring connector.

Bruce C
'04 K1200RS Capri Blue(totaled)
2008 Triumph Sprint ST

Last edited by brucecha; May 18th, 2008 at 3:16 pm.
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post #8 of 17 (permalink) Old Jul 18th, 2008, 12:54 am Thread Starter
 
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I fixed the turn-signal switch and wish to give you guys hints

Quote:
Originally Posted by cobbler
Then there are two little silver head screws on the inside that must come out because they hold the cover on to all the guts. One you can see on the top right and the other in underneath a silver sticker, yes under a sticker.
Oh Cobbler, on all counts you were right on the money!

With everyone's help (and that of a fellow rider), in two hours, we disassembled, diagnosed, and fixed the balky 1999 BMW K1200RS left turn signal switch!

As you noted, there were a few "mysteries" to be solved:
- The first mystery was to locate second of two #6 torx screws on the inside of the turn signal combination switch left assembly. Just like you said, it was in the middle of the sticker; I just removed the sticker instead of punching a hole in it. In the beginning, I didn't have a #6 torx screwdriver (that's really really tiny for a motorcycle) so I used a 1mm allen wrench. Putting it back, I bought a set of really really tiny torx screwdrivers.

- The second mystery was how to remove the orange paddle on the outside of the turn signal switch assembly. Turns out you destroy the black tie wrap and remove a small plastic bulkhead panel, and only then does the end of the orange turn switch paddle come out.

- The third mystery was how to disassemble the half-inch tall half-inch wide switch cylinder; the trick here was brute force, gently but firmly applied. I worried that I would never get it back together; but, it turns out, you can take it apart and put it back together but the top of the cylinder is directional so mark the white plastic before you take the switch cylinder apart.

- The fourth mystery was how the damn thing worked! It turns out that the 1999 BMW K1200RS turn-signal switch is an always-on contraption. Yup. The two metal contacts are always in contact except when you momentarily depress the orange paddle, which presses on the white cylinder, which pushes down a paper thin 1mm sliver of plastic in between the two brass contacts, separating them, and causing the turn signal to activate.

- The fifth mystery was a diagnosis of the problem. It turned out there was a tiny aphid-sized lump of black goo on the tiny 1mm wide by 1mm tall paper-thin plastic sliver. The black goo was keeping the contacts open, not allowing them ever to close, so they were always in the "cancel" mode. Wierd! I never would have guessed this had I not seen it with my own eyes, that black lump was smaller than the size of a pin head.

- The last mystery was how to put it all back together! It took a few tries (the head of the cylinder itself is directional for example, so you have a 50% chance of getting it right unless you mark it beforehand - I recommend you do 'cuz the more you manhandle it the more chance you have of breaking it). My mistake; your gain.

- In order to put it back together, I had to remove the third #2 philips bolt on the underside of the switch assembly. You really don't need to remove it until the end (go figure) when you try to reassemble the tie wrap and black plastic wire separator which holds one end of the orange paddle in place - but again - my mistake is your gain. You may as well remove that third #2 Philips bolt at the beginning.

Hopefully I'll have time to post some good pics so the next guy has the benefit of Cobbler's knowledge!



See also wiring diagrams at
http://www.k-bikes.com/forums/showth...741#post113741
and a similar discussion at
http://www.k-bikes.com/forums/showthread.php?t=11371
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Last edited by donnatello; Jul 18th, 2008 at 1:58 am.
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post #9 of 17 (permalink) Old Jul 18th, 2008, 1:32 am Thread Starter
 
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It wasn't a loose connection as much as it was a loose disconnection!

Quote:
Originally Posted by milkman
suggest taking it apart and looking for loose connection.
Hi Milkman, you were right but, in a way, it was a loose disconnection!

Wierd, but, the 1999 BMW K1200RS left turn signal switch button works in reverse; that is, it's always closed except when you press the orange paddle.

When your thumb presses on the orange paddle, the paddle depresses a white hollow cylinder which has a tiny 1mm wide and paper thin plastic guillotine which electrically separates the two brass contacts momentarily.

Apparently I had a pinhead sized lump of black goo inside the almost hermetically sealed switch cylinder which was apparently holding the contacts open or perhaps it was conducting electricity which effectively kept the contacts closed, even when the guillotine was in between the turn signal switch contacts.

I hope the photo shows that dirty white guillotine as it was really really tiny.

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post #10 of 17 (permalink) Old Jul 18th, 2008, 1:47 am Thread Starter
 
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Brute force can open the hermetically "sealed" turn-signal switch cylinder

Quote:
Originally Posted by DaveTheAffable
the switch is sealed. It's small, has a little rubber cover. I uncovered it, air sprayed it, then used some 'electrical contact cleaner' spray and found... it didn't help.
Hi Dave,
You were right but it turns out you didn't go far enough. I wouldn't either except all you guys gave me the confidence to keep going.

Yes the switch is sealed. It has a black rubber cap on the cylinder head cap which itself is on the cylinder tube which contains the guillotine which separates the contacts embedded in the bottom half of the cylinder black plastic which has the two wires leading from the always closed, momentarily open brass contacts.

Basically, to take apart the switch cylinder, on has to ...
1. Remove the black rubber cap with a tiny screwdriver pry bar (jeweler size)
2. Mark (this is important it turns out) the orientation of the white plastic cap
3. Pry the white plastic cap off (it does NOT twist); it must be pried straight up as it has two keyholes along the cylinder length 180 degrees apart.
4. Pry the cylinder and spring assembly off the black plastic contact base
5. At this point, you can clean the cylinder with alcohol, WD40, and a paper towel (that's what I used anyway).

Note that this switch cylinder is about the width of your pinkie so the difficulty is that you need a watchmaker's patience to reassemble the switch without breaking it.

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