Some of you may have followed my tale of woe. I'm back to now tell you it's all fixed (permanently. Not temporarily). It's bit of a story, but I think will be of value to others. I've learnt a few things, which I think will be useful to others... Fast forward to the end of your want the crux of the issue.
Below also are links to my original posts on this if you're really bored and want to get the whole picture, read on.
For those unfamiliar with the story. Riding back from Italy. On the second day of the return trip, I broke down on the Autoroute near Metz. It was not a roadside fix (I do carry a well thought out took kit).
I get to a BMW dealer who diagnosed and fitted a new alternator. I thought it was a good call actually as I have run heated gear for dental years. So I head home in atrocious weather, safe in the knowledge all is now good. I was unnerved however with a yellow warning on the dash as I bombed up an unlit M20 after leaving Eurotunnel, late at night and an empty road. I kept going!
2 days later, I get to clean the bike as it was minging and covered in salt after the ride through Switzerland. It cleaned up well! But on pressing the starter to get it running and dry it off as I normally do, nothing. Dead. Except for an electrical burning smell
wtf!
I get that tank off and get a bizarre display of spontaneous sparks out the back of the alternator. Battery disconnected in a hurry!
Following intermittent days and days of looking for the short I gave up and got the bike to Jap & German in west London - highly recommend them. No bs. Pleasant and they know the bikes inside out.
They found the fault real quick and got on with fixing it. I rode home
But this was not the end... When I was searching for the fault I discovered something was missing. Specifically a device connected to the new alternator. Something BMW describes as a "voltage protection" cable. On the BMW service CD is called "surge protection diode". Some of you might know it as a Zener diode.
In France they told me BMW specified "a new earth cable" must be replaced with a new alternator, but it didn't arrive, so they would just fit the old one - at this point, I should highlight that this was clearly something lost in translation - they didn't mean an earth cable. But in their rush to get me going, they omitted to refit the old cable...
So all the red herrings in my diagnosis finally made sense. Because I just couldn't understand how I got home, in terrible weather, but I wash the bike and bang, same fault - but it wasn't actually the same fault...
If you're still with me, here's the whole program:
- I break down
- BMW diagnosed failed regulator/rectifier. Good call actually. So new alternator fitted.
- They forget to fit the voltage regulator cable
- I ride home - with great luck, nothing goes wrong.
- 2 days later, on pressing the start button, I get burnt out wires... Which only now I understand as separate from the original breakdown, it was down to the missing voltage regulator cable...
The bottom line is. On these hex heads/twin cams there is no fuse box, the ZFE detects and shuts down things misbehaving. Without the voltage protection cable, the ZFE is first in line to a fault. If you're really unlucky, that gets damaged.
Yesterday I fitted the voltage protection cable. A proper fiddle with the alternator in place. But I now feel a lot better. Jap & German did a neat fix. Really happy with their work
I now know the importance of that insignificant looking device on the alternator! Don't forget it!
Some pics below.
I can't finish without big thanks to all those actively trying to help and wind me up with killer humour
. It was a big stretch for anyone to diagnose this online! But this forum is treasure
The original breakdown:
The second breakdown (at home!):
The missing link:
Below also are links to my original posts on this if you're really bored and want to get the whole picture, read on.
For those unfamiliar with the story. Riding back from Italy. On the second day of the return trip, I broke down on the Autoroute near Metz. It was not a roadside fix (I do carry a well thought out took kit).
I get to a BMW dealer who diagnosed and fitted a new alternator. I thought it was a good call actually as I have run heated gear for dental years. So I head home in atrocious weather, safe in the knowledge all is now good. I was unnerved however with a yellow warning on the dash as I bombed up an unlit M20 after leaving Eurotunnel, late at night and an empty road. I kept going!
2 days later, I get to clean the bike as it was minging and covered in salt after the ride through Switzerland. It cleaned up well! But on pressing the starter to get it running and dry it off as I normally do, nothing. Dead. Except for an electrical burning smell
wtf!I get that tank off and get a bizarre display of spontaneous sparks out the back of the alternator. Battery disconnected in a hurry!
Following intermittent days and days of looking for the short I gave up and got the bike to Jap & German in west London - highly recommend them. No bs. Pleasant and they know the bikes inside out.
They found the fault real quick and got on with fixing it. I rode home
But this was not the end... When I was searching for the fault I discovered something was missing. Specifically a device connected to the new alternator. Something BMW describes as a "voltage protection" cable. On the BMW service CD is called "surge protection diode". Some of you might know it as a Zener diode.
In France they told me BMW specified "a new earth cable" must be replaced with a new alternator, but it didn't arrive, so they would just fit the old one - at this point, I should highlight that this was clearly something lost in translation - they didn't mean an earth cable. But in their rush to get me going, they omitted to refit the old cable...
So all the red herrings in my diagnosis finally made sense. Because I just couldn't understand how I got home, in terrible weather, but I wash the bike and bang, same fault - but it wasn't actually the same fault...
If you're still with me, here's the whole program:
- I break down
- BMW diagnosed failed regulator/rectifier. Good call actually. So new alternator fitted.
- They forget to fit the voltage regulator cable
- I ride home - with great luck, nothing goes wrong.
- 2 days later, on pressing the start button, I get burnt out wires... Which only now I understand as separate from the original breakdown, it was down to the missing voltage regulator cable...
The bottom line is. On these hex heads/twin cams there is no fuse box, the ZFE detects and shuts down things misbehaving. Without the voltage protection cable, the ZFE is first in line to a fault. If you're really unlucky, that gets damaged.
Yesterday I fitted the voltage protection cable. A proper fiddle with the alternator in place. But I now feel a lot better. Jap & German did a neat fix. Really happy with their work
I now know the importance of that insignificant looking device on the alternator! Don't forget it!
Some pics below.
I can't finish without big thanks to all those actively trying to help and wind me up with killer humour
. It was a big stretch for anyone to diagnose this online! But this forum is treasure The original breakdown:
The second breakdown (at home!):
The missing link:
