K75S no start, well sometimes it does :/

[johnnyalpha]

Good Morning, it's me again, with a start/No start puzzle.
K75S 94K miles
Bike had been running well, no funny electrical issues i.e. no flasher malfunctions etc etc.
Last job before this happened was resurrecting the flasher 4 way switch.

Symptoms, key in and press starter button, then NOTHING, no fuel pump whine, just nothing, hard to tell if any of the relays are trying to click (getting deaf?)
However, have noticed that the headlight stays ON, no going off when starter pressed, as we usually see.

Now and again bike will start, on these occassions, the headlight will go OFF when the starter button is pressed, bike will run normally thereafter.

DID notice that fuse 1 (top one) has blown, but have replaced, and the symptoms above persist.
This morning, there was no Sound at all when starter button pressed.
Oh, forgot to mention, my green N light has disappeared BUT the gear indicator still works, and is accurate i.e. 0 = Neutral, 12345 etc.

I took off the starter switch assembly, didn't try to take it apart, BUT there doesn't appear to be any corrosion or pitting there, no signs of arcing.

NOT tried rocking bike back and forth in gear, as has been suggested (at work will try when I get home)

Any help advice greatly appreciated.

Struck by the sudden loss of the N green light and the presence of the gear indicator though.

The bike has no sidestand switch

Also NO clutch switch on the bar. BUT found the connector under the tank, the Green/black and Black/Green, shorted this out, AND on the odd occassions the bike starts, it will NOW start in gear (so glad my early "training" of starting any bike with clutch lever in and front brake on is still ingrained).

So,basically it starts as per normal

OR there is NO effect on pressing the starter button (more often the latter).......as I say hard to tell if any relay is trying to work or not, I hear no clicking
no fuel pump whine, no starter motor turning, nothing :(

any help much apprecciated, Johnny (Edinburgh Scotland)

[Scott_]

Well, just a quick note.
The power source for the starter button is, EITHER the clutch lever switch(which you have now bypassed, so the bike will be able to start while in gear), or the output of the gear indicator pcb in the inst cluster.

Here's a good write up by Bert Vogel...
http://www.motobrick.com/index.php?topic=5067.0

[johnnyalpha]

Cheers Scott, been studying this, thanks very much. Must say right away, I am NOT happy with electrical issues :/ not my forte. 
Going to try to rock the bike in gear.
Check if the headlight goes out when I thumb the starter
Check fuses 1 and 7, as these seem to be implied in a lot of starting issues.

Have ordered starter brushes and odds and sods, including a new LSR from Motobins.

thanks for taking the time to answer, Best Wishes Johnny

[johnnyalpha]

A wee update. Looked at the bike yesterday after work. Keys in, all the usual lights light up BUT still no green N light.
Thumbed the starter button and the bike fired up, I wasn't expecting this. I was expecting the stoney silence that
had been happening of late.  Switched off with key, repeated above 3 times. Put bike into gear and it fired up, I had shorted out the clutch interlock switch if you remember.

Now I was well puzzled. 

The N light was still out, but the GPI still shows the correct gear and neutral. The night before I had NO sound on thumbing the switch,no fuel pump/starter motor and I could not hear any relays clicking. And the headlight stayed ON when I thumbed the starter button.  Now everything seemed to be working as per usual, apart from the N bulb. The Headlight went off when I thumbed the starter button, and the bike fired up, all very odd and perplexing.

I then proceeded to put the bike into gear, 4th or 5th, and let the clutch lever out and pushed the bike back and forth, I think this was to move the starter motor so that it moved off a bad/dirty part of its commutator ?

Anyway, I heard the starter motor moving and "growling" for the want of a better description,but then the fule pump fired up for just a second or two. This effect was reproducible each time I did this.

I know that electrical problems are very hard to diagnose, especially over the internet, but if anyone can shed any light on what may be happening I would be very grateful.

Is it possible that I "upset" the load shed relay when I was splicing the clutch interlock switch ? the green/black and black/green wires ?  And it had released itself overnight ?  TBH not sure of the sequence of events that occurs when the starter button is pressed, I know that there are articles out there, BUT understanding them is another thing :)

Anyway, I ordered new bushes for the starter motor, so I should still intend to clean the commutator and replace these in any case.

I must say that the BMW K eries electrics do puzzle me more than most :/

thanks everyone, ride safe, Johnny

[K75RT Keith]

Radical thought:  The bulb may have burned out.  Have you checked the bulb?

[johnnyalpha]

Hi Keith, nope not had the intrument cluster apart as yet :)

MMhh I thought that the Gear position switch activated the starter button, not the bulb itself ?

I think that a blown bulb stopping the bike from firing up would not be a good idea, BUT nothing really surprises me with BMW electrics :)

Johnny

[Scott_]

MMhh I thought that the Gear position switch activated the starter button, not the bulb itself ?

I think that a blown bulb stopping the bike from firing up would not be a good idea, BUT nothing really surprises me with BMW electrics :)

Johnny

The bulb is only an indicator of the gear position pcb assy. The output of the assy feeds both the bulb and the starter button.
Yes it's possible that the bulb could be bad, but just a bad bulb would not prevent the neutral start circuit from allowing the bike to start.