K75 Help Needed

[foolonawheel]

I'm planning on buying a K75S. I went to look at the bike and really liked it. The battery was low so the owner hooked up a 10 amp battery charger (yes, polarity was correct). Bike still didn't crank. After several attempts to crank it all circuits stopped working. The fuse for the instrument cluster popped, we replaced it but no go.

Is there a fusable link? Any relays that we may have burnt that would kill all circuits? Any advice is much appreciated as I would like to deal with it without taking an unpurchased bike to the shop.

Thanks everyone.

 

[pglaves]

There is no fusible link.

There is no fuse that could kill all circuits.

It is possible that you killed the load shed relay which would kill several obvious circuits such as the headlight, but ...

I suspect it now has an open, failed cell in the battery.

It is almost impossible to troubleshoot a K75 electric system unless there is a reasonably charged, sound battery in place. That is where to start.

You are also at risk of sticking/welding the contacts on the starter relay trying to start that bike with low voltage. If/when this happens it just keeps cranking until you disconnect a battery cable because the relay won't release. Be careful.

 

[foolonawheel]

Thanks for the response Paul. Most of my BMW experience is with airheads. The seller didn't have a volt meter so I wasn't in a position to do much in his driveway. I'm going to go ahead and buy the bike. I've been missing having a sensible bike.

 

[kayseventyfive]

I've been missing having a sensible bike.

Sensible bike.

I like that.

.

 

[Consultant]

K75 warning

Be careful if the K75 has ABS. Trying to start with a low battery can fry the ABS computer. Clymers has a good diagram of the K75 wiring including color code. Also, ignition switches are known to fail, shutting off all power including to the starting relay. My K75S starter switch got flaky and would not allow cranking.