running light short

[Matt Chapter]

Took the R65 out for inspection today; I've had an intermittent short in the instrument / running light circuit for a while but thought nothing of it.  The inspector noted my tail light was out (brake light works fine) and now it's time to dig in.

Anyone have magic bullet suggestions?

[mrclubike]

Check the fusees
They don't protect much but their is one for the marker lights
Then Change the fuse panel out to a modern ATC style
The VW style fuses tend to oxidize and loose connection 

[mrclubike]

You really should upgrade the fusing to protect the whole bike as much as possible
Split the harness right after the main splice and add fuses into the unprotected circuits
These bikes are heating element just waiting to happen   
My fuse ratings are a little high but they are better than nothing

[Matt Chapter]

I suppose that's an idea, but it won't directly fix my problem unless the short is at the fuse.  It's an intermittent problem.

I guess I need to go buy a volt meter and get in there.

[mrclubike]

 Okay lets clarify what your problem is
#1 Do you intermittently blow the fuse to the tail lights (that is a "SHORT")
#2 Do the tail lights intermittently just go off and come back on (this is a "OPEN" in the circuit)

If it is #2 
Because the front and rear is acting up more than likely it is a bad connection between the fuse and the clips that hold the fuse in.
Look at the schematic I posted The front and rear circuits split at the fuse holder that is why it is more than likely the problem 
This is a common problem with this type of fuse because they oxidize with age
Give the fuse a twist in the holder and they will come back on
I had this same  problem before i changed out the fuse holder to the newer style ATC type fuse

I have 6 Volt meters 3 amp clamps and 2 oscilloscopes I do this kind of thing a lot   

[Matt Chapter]

Ah yes, the instrument lights and tail light go out and don't come back until they're pleased.  Fuses look fine at visual inspection, removed and replaced / rotated with same result.

I just went into the garage with fingers crossed and noticed that turning the key to the accessory position, the instrument lights and tail light are on, but when moving the key to the run position, they turn off.  Definitely suspicious of a wiring problem now!

I remembered that I did a bit of a hack job on the right hand control wiring two batteries ago, so that's probably my next investigation point.  I've thought about doing the fuse conversion, but I'm lazy, I might just spend for an R1200 RT instead...

[mrclubike]

In stock form the running/park-light circuit does not run to the handle bar control's
It goes from the key switch straight to the fuse  and then splits front and rear to the lights
I would suspect the key switch or the terminal the park light circuit is connected to on the key switch
I was sure hoping it was just the fuse

[Matt Chapter]

After some fiddling, I got as far as I originally wanted, which was a passing inspection for registration purposes.

I have a Euro spec left control installed, it has three positions, all lights off, running lights on / headlight off, all lights on.  Fiddling the switch brought temporary running light operation, so I suspect the switch is failing.  Sadly this is my third switch, pretty underwhelmed with the durability.