Headlight failure GS500F 2006 US model

[Rallyfan]

Hello everyone,

My headlight doesn't work. All the other lights on the bike work fine, but neither beam setting of the headlight works. So far, I've done the following:

1. Replaced the left hand switch gear (the entire thing). The harness goes under the tank, and I replaced the integrated switch that has the horn, turn signals, and beam setting plus choke lever. All of it. No solution.

2. Replaced the bulb. No solution.

My symptoms are exactly as seen in this video, which does not contain a solution:

https://www.youtube.com/watch?v=TNm86A-FIe4

My symptoms are also like this post, which also does not contain a solution since my bulb is fine:

http://gstwins.com/gsboard/index.php?topic=73757.msg885084#msg885084

So... I have clearance (parking), tails, brake, and turn lights but no headlight.

EXCEPT: When I honk the horn, sometimes the light comes back on.

Anybody run into this and actually fix it?

Thanks!

[SK Racing]

Did you replace the switch with an original Suzuki item? Chances are that the colors of the wires are different and don't match the original. Other brands (Honda, etc.) use different color coding on the wires.

Did the light stop working before you replaced the switch?

[Rallyfan]

Thanks for the response.

Original Suzuki switch, yes.

The light stopped working before I replaced the switch, yes.

The switch came with a harness and everything from the handlebars to the connector under the fuel tank is replaced (original Suzuki).

[SK Racing]

Well, it can only be two things. Either the light doesn't get power or there is a problem with the earth wire from the light down to chassis earth. Both easy to test with a multimeter. Test power with the meter set to DC voltage and test earth with the continuity test function. Make the tests at the back of the light bulb holder.

Once you've established if the culprit is power or earth, you can delve deeper into the cause.

[Rallyfan]

Thank you!

I've measured both 0V and 6V potential difference between a filament terminal and earth on two different occasions. This was challenging to interpret for me.

Moreover the problem is on the one hand intermittent, and on the other not induce or — I cannot make the light fail.

The above has made troubleshooting less fun that none might expect.

Anybody here had a similar experience?

Does the wiring fail somewhere usually (that I have not already replaced as part of the switch harness)?

Thank you.

[SK Racing]

You should see about 12V, not 6V.

I can think of one possibility: That the earth cable is broken somewhere. At the rear of the engine, low down there should be an earth cable bolted to the engine casing. Ensure that it is connected.

Have you checked continuity on the earth wire? Referring to the picture below (which is a snippet snippet from the wiring diagram), it is the Black/White (B/W) wire.



The Yellow wire is hi-beam and Lo-beam is White. Depending on the position of the low/high beam switch on the left handlebar switch, you should be able to measure 12 Volts on either the Yellow or White wires.

It is important that you verify that the Black/White wire has continuity to chassis ground (earth) and also to a bare patch of the engine casing.

If you see intermittent results, it may mean loose connectors or a broken wire somewhere.

[Rallyfan]

Thanks, that's what I was thinking.

It looks as if the Earth is *not* switched, the (+) is switched instead.

Therefore, since the engine and all other electrics run even if I have no headlamp working, if I were to bypass the harness and connect the (-) from the headlamp socket to the chassis, that *should* solve the issue anyway — am I thinking correctly?

[SK Racing]

Yes, that is how I would test it.

The Yellow and white wires carry 12V depending on which way the Lo/Hi switch is toggled.