Hazard light stays on

[jdwincu]

I have a 2003 F650CS which I recently bought. Sometimes when I turn the key on and then off the light in the hazard switch will stay on (but not always) slowly draining the battery. It doesn't seem to do it if the bike has been running or after I've been riding. The dealer replaced the hazard switch, but this didn't help. Going to have the dealer take another look, but I'd appreciate any ideas folks might have which I could share.

Thanks.

[RkyMtnMan]

Disclaimer: I'm not intimately familiar with the CS; my own bike is an '05 GS Dakar.

That said, however, I'm guessing that the hazard flasher circuitry is likely to be at least similar between your '03 CS and my '05 GS. That assumption underlies what follows.

There are three diodes buried deep beneath the relay tray in the electrical box that are key to the operation of the hazard circuit. They're what make possible things like:

The hazard flashers STAY ON even when the bike is switched off
The hazard flashers cannot be turned ON without the bike being on (as, say, by a malicious, random stranger hoping to drain the battery on your unattended bike)

These diodes are fragile and under-rated. Their load limit is 2 amps, and they experience a CONSTANT 1.8 amp load whenever the bike is running (whether the hazard flashers are on or not).

One of these diodes fractured and shorted on my bike; the result was a very odd set of symptoms:

The bike could not be turned off with the key when the hazards were flashing
If I turned the bike off with the kill switch when the hazards were flashing, it could be restarted WITHOUT the key.

Bottom line: a shorted diode can "back feed" other circuits on the bike, like the ignition & starting circuits.

My own dealer had no real "repair strategy" -- other than to guess and throw parts at it (at my expense, of course). His first guess was the ignition switch; his second was the main computer module under the seat. I ended up repairing it myself with a 75-cent diode from Radio Shack (a more appropriate 3-amp diode, of a more robust epoxy-style construction).

I would suggest getting your hands on the proper electrical diagrams for your bike and putting them in front of someone who knows how to read them -- which may or may not be your dealer's service department. Have them look for anything that might intermittently back-feed that illuminated switch when the key is off.

Good luck.

Link to an illustrated discussion of my bike's diode problem and subsequent repair (http://f650.com/phpbb3/viewtopic.php?f=9&t=230082&start=15#p489854)

[jdwincu]

RkyMtnMan: Goodness. Thanks very much for the very clear and helpful suggestion (along with the pictures of the work you did). This is certainly above my pay grade, so I'll likely need some help from dealer/repair shop. However, I'll take all of this along and hope that will help them figure it out. I assume there is no rush on this as long as I always check and make sure the hazard lamp hasn't stayed on. Thanks again.