Electrical short and blowing fuse for Neutral and Oil Pressure

I was finishing up the wiring on the LED Turn signals on the rear of the cb750. The bike had been running pretty good so I didn't think anything to reach up and start the engine to check if the lights worked without any stray voltage flashing after I added resisters to the brake and turn signal circuits.

I had forgotten that my son was sitting on the bike a few days prior and left the bike in gear so when I cranked the engine the bike lurched forward off the side stand and I was just barely able to break the fall as it dropped onto the left side.

Somehow this resulted in a no start condition with the engine cranking and backfiring but ultimately not turning over.

I checked the fuse panel and found the glass tube fuse for the Neutral and Oil pressure blown. No worries, I'll replace it with the spare and boom, blown as soon as the ignition turns on.

This is a head scratcher for me. The wiring looks good so I'm not sure why it's suddenly acting like this after a controlled fall.

After unplugging the wires from various parts of the motorcycle (brake lights, clutch/neutral diode, speedo, fuse panel) I finally narrowed down the short to the harness for the digital speedo. When I disconnected the speedo and probed the black and brown wire on the bike side of the wire, there was no short.

Probing the section of wire from the fuse panel to the headlight bucket also showed no short. I've been meaning to clean up the wiring for the speedo. Need to remember to take that as a winter project.

I also discovered that my clutch switch has failed and always reports that the clutch is pulled so I'll need to try and replace that also.

By reason of deduction, the short could only be happening in the connection for the digital speedo. The Black and Brown wire used to provide a ground for the neutral and oil pressure lights and when I was connecting things up, I just put the black/brown wire connected with the green ground but in reality, the Neutral and Oil Pressure share a common ground with the rest of the speedo now so the black and brown are no longer necessary.

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