Headlight switch wiring loop

[goggles]

I have seen reference to a "wiring loop" that runs to the headlight switch (number 7 in this post https://www.thegsresources.com/_foru...ewbie-Mistakes ). Another post I read mentioned this happened in part due to the discontinuing of a switch for the headlight.

My particular bike has a headlight switch. I am assuming I need to leave the "wiring loop" alone since it has a purpose on my bike?

[NavyDad]

If your bike has the switch to turn the light off/on then yes you can keep the loop. When Suzuki went to headlight on all the time and no on/off switch they didn't remove the loop from the harness and it doesn't help the already marginal charging system.

[Steve]

Does the switch on your '80 550L actually work?

I ask that because most of them were blocked off, not allowing you to turn off the light. Some owners have removed the block, restoring operation of the switch.

If you have the stock R/R (rectifier/regulator) in the charging system, leave the wiring alone, but make sure all the connections are clean. If you have upgraded to an SH775 series regulator, you can bypass the headlight loop.

In later bikes, there was a short jumper under the fuel tank that fed that one stator line back down to the R/R, not getting anywhere near the now non-existant headlight switch. On those bikes, it makes sense to bypass that loop to minimize the number of connectors in the line between the stator and the R/R.

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[goggles]

The switch has worked since I bought the bike.

I replaced the original r/r with one from duneage when I started having charging problems.

I am planning on doing electrical maintenance and maybe some of the relay mods so research on those lead to the question above.

[Steve]

Measure the voltage at the various load points before doing any relay mods.

If the whole system is low, it would make more sense to use ONE relay to power the fuse box and only use the ignition switch to trigger that relay.

[goggles]

Right now the positive cable goes to the starter relay and a smaller wire goes from relay post to fuse box. It sees like the positive feed is almost going straight to the fuse box.
How does this differ from what you describe?

[Steve]

Keep following the line. That "positive feed" only goes to the MAIN fuse, then to the ignition switch, then back to power the other three fuses. There are several connectors between the main fuse and the rest of them, including the ignition switch, which is not exactly known for living in a pristine environment.

Grab your voltmeter, do a quick check. Ground the black lead, clipping on to the battery negative terminal would be perfect. Flip the 'kill' switch to OFF to minimize draw on the battery. Turn the ignition switch to the ON position. Check the voltage at the battery positive terminal. Check the voltage at both ends of the MAIN fuse. Check the voltage at both ends of the other three fuses. Check the battery positive terminal again, to make sure it has not dropped very much. Turn the ignition key OFF. How much of a difference did you see in the fusebox? If there is a sizeable drop, my first suspect area is the ignition switch, as ALL the power to run the bike goes through there, and it is switched ON and OFF every time you move the switch. That is a lot of wear and tear.

If ALL of the readings were within a volt of the battery, you don't probably don't need to add any relay mods. To be SURE, Remove the fuel tank and headlight, so you have easy access to some connectors. With the key ON again, compare voltages at the LIGHTS fuse and at the headlight connector. Compare that again with battery voltage. Compare voltages at the IGNITION fuse and at the coils. Compare that again with battery voltage. Inside the headlight bucket, find the brake wire, compare voltage there with the SIGNALS fuse.

If the voltages in the fusebox are pretty close to battery voltage, the connections are evidently pretty good between the battery and the fusebox. If the voltages between the fusebox and the load points are pretty close, they are evidently clean. If not, you need to clean some connections. If the voltages between the battery and fusebox are low, a bypass relay to power the fusebox might fix ALL your low voltages.

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[goggles]

Thank-you for the explanation. I can understand how that could limit voltage.
The bike is stored elsewhere but will follow the leads when I can .

[Steve]

I have always been amused by those who have done a headlight relay mod, and an ignition relay mod, but not bothered with a relay for the signals (which includes the brake light). If you are doing two out of three, there is a good chance that the fusebox is low on voltage, so a single relay that powers the fusebox and is triggered by the ignition switch just makes more sense. Quite often, the contacts on the back of the fusebox are pretty wonky, too, which makes replacing the fusebox a practical upgrade. I have the Eastern Beaver fusebox on all of our GSes. Besides simply being a new fusebox with fresh connections, it has more circuits available, which is great when you are adding accessories to a touring bike.

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