Blowing Ignition Fuse

[AbbandonZK]

When I disconnect the ground wires from the battery and run the black lead to frame ground. The ign post on the switch beeps for continuity the lights show a voltage drop of 1.9 no beep. When the main ground is tested the L position beeps for continuity and the ign post shows a voltage drop of 1.5.

[confab]

Continuity between the ignition lead and ground is a problem..

I would disconnect that and trace down it.. Because a low impedance connection between that lead and ground is what is blowing your fuse.

[Tattooo]

When I disconnect the ground wires from the battery and run the black lead to frame ground. The ign post on the switch beeps for continuity the lights show a voltage drop of 1.9 no beep. When the main ground is tested the L position beeps for continuity and the ign post shows a voltage drop of 1.5.

Yep just like I said in my first post...............

It sounds like you have a grounded hot and a very weak ground........

[farmall]

Continuity between the ignition lead and ground is a problem..

I would disconnect that and trace down it.. Because a low impedance connection between that lead and ground is what is blowing your fuse.

Is the key switch old? They are disposable and I get about ten years use out of Drag Specialties generics. They've been known to short to ground internally.

I ohm across the disconnected switch in all positions and ohm each terminal to ground in all positions. (If it's the least bit loose I replace it. They're cheap.)

You can bypass the key switch using a jumper lead (disconnect the switch) to check each system without switch involvement.

BTW ensure the points are open when checking the circuit because they apply ground to build up power in the coil. I would disconnect everything else and ensure the ignition works by starting the engine as that's the easy way and a short to ground will prevent start.

When a test light connected from the points side of the coil to ground lights, the points are open (that's how static timing lights work).

[AbbandonZK]

Thanks for the help guys it was the tachometer that was passing voltage. The light circuit read to the multimeter as a open circuit. And the hot to ground had a voltage drop of 1.9. Once I clipped it off the bike I had two separate circuits. I also discovered the headlight outer housing passing voltage thru the frame. The headlight has a blue high beam indicator light that’s unshielded.

[Tattooo]

The headlight has a blue high beam indicator light that’s unshielded.

How many wires on the blue light???????????

[AbbandonZK]

The blue light is actually a lens that is illuminated by a brazed light in a socket underneath it.

[Tattooo]

The blue light is actually a lens that is illuminated by a brazed light in a socket underneath it.

Yea I know what it is and how it works, I just want you to look and see how many wires are on the bottom...... One is my guess...........

My questions are to help you learn about wiring...........

[confab]

Glad you got it.. I think Farmall's advice above is very good - Break those circuits up in order of importance so one failure doesn't take everything down. Lights are important too. Maybe IGN and Headlamp on their own, separate, fuses.. because they're both critical. (at least at night)

[AbbandonZK]

The headlight indicator light has 2 wires red and black the black is linked to the headlight bulb wiring.

[Tattooo]

The headlight indicator light has 2 wires red and black the black is linked to the headlight bulb wiring.

Awesome........ That's the later setup........

You are seeing what does what getting your hands in there.............

[Tattooo]

I think Farmall's advice above is very good - Break those circuits up in order of importance so one failure doesn't take everything down.

That's exactly why when I wire a bike the first click of a switch ONLY the ignition works, Not even the tail/brake light comes on..............

Plus back in the day it was also nice when you were running from the cops at night........ LOL

[AbbandonZK]

I’m considering disconnecting the indicator light on the headlight and placing a diode and 100K resistor on the tach backlight blue wire. Anyone opinion on this? It should stop the headlight outer shell from touching the frame ground and the tach light from passing voltage to the ign.

[confab]

I would just take it apart and fix the problem.

We all default to what we know and what I know best is cars, so.. Being the Harley N00bie here, others may have differing views..

But, having said that and IMO, adding a unnecessary resistive load will consume more current, add heat and another point of failure, and can damage wiring depending on how it is sized. Most little diodes are in place around things like relays and solenoids, and they're there to spin out voltage transients you don't want dumped back into the controller that operates them. Yeah, they're a "check valve" for electricity. That's true.. But they aren't really supposed to correct a dead shorting condition.

That headlight housing, especially, should be an easy fix. I dunno what your tach is like, but I couldn't imagine it is much more difficult.

Good luck!

[confab]

PS: All you really need to do here is go in, look and make sure the current is running through the load first (a bulb in this case) and then going to a good ground. Somewhere is it not and that is the problem. And it is probably a shitty bulb socket or something like that.

And that should fix you right up.