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Fog lights not working - common failure mode?


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The background: neither of my fog lights ('04 R1150RT) is working. I checked one bulb, it was fine. Checked power to the bulb, none found. Checked power in and out of the switch, it's OK, i.e., one wire is ground, one is always +12, and one is +12 when the switch is on (checked at the connector. So I tried swapping relays, no dice. So I looked to see if +12 was getting to the trigger input on the relay socket (relay farthest to rider's right, front of box). Nope, the only +12 is the load power input. So, I'm guessing I've got a broken wire someplace between the switch and the fuse box.


Having said all that, has anybody run into this before, and is there a likely place for such a break to occur? I found an old thread on this subject, and the OP said he found a broken wire "in the front". That doesn't narrow it down much. Ideas? Or should I just pull the nose fairing and start tracing?

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happened to me once and it came out to be the fuse (15A position #10).

Looks like you will be busy with the electrical diagram and the fluke this weekend!

Good luck...

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This happened to me and it may be my thread you saw. Found a broken wire by the dash switch. It was just a pain in the a** to pull all the plastic off and search for the break. It was due to the rubbing of a wire on metal.

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The link I provided is of no use to you as it was either the line or load wire crimp or connector that failed.

As you stated your failure is lack of 12v+ to the relay coil.


Never mind blush.gif

I hadn't had my 2nd cup of coffee yet dopeslap.gif

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  • 3 weeks later...

I just thought I'd bring this to closure. It turns out that:


1) I can't count to 10

2) Visual inspection of fuses is not always sufficient.


Yup, it was a blown fuse, number 10. The fuse separated right at the terminal, rather than in the middle as is more common, so it took very close inspection to see that it was blown. My multimeter is not so easily fooled, however. And it didn't help that I was going by the picture in my Haynes manual, which made it look like fuse number 10 was on the right side of the divider. In fact, that's fuse 11.


However, I can now tell you that I have verified ALL of the wiring for my fog lights. And that the wiring diagram in the Haynes manual has the wrong pin numbers for the fog light relay. What finally hit me with a clue-by-four was when I couldn't find +12V on ANY of the terminals of the relay with the switch off. D'oh!


And I even knew why the fuse blew, and had reason to suspect the fuse would be blown because of the failure of a voltmeter I had installed that was feeding off the fog light switch. I can be so freakin' dense sometimes!


As they taught my wife in medical school, "when you hear hoofbeats, your first thought should not be of zebras".


Thanks for your help, anyway.

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