headlight doesn't light, 83 Heritage trouble shooting.

[gggGary]

More of a guide than a question. bought a 10K miles 83, headlight didn't work. I had the headlight shell all apart anyways and checked a bunch of stuff then it worked. fast forward a year, on the road to show the bike to a prospective buyer and of course headlight stopped working. Well I traced back, fuse good, 12 volt through it. I am parts rich, so I tried swapping, reserve lighting unit, no joy, starter/headlight relay, no joy. Manual is a bit unclear on this, but the feed for the headlight relay coil is a separate lead off the alternator. (yellow wire) with a connector found above the air cleaner. Anyway took the LH cover off and the outer brush was worn down pretty far, put in a new one (I said I was parts rich) while I was there, I lightly sanded the rings with fine paper and that was it headlight is on. So on a late model bike the headlight not lighting may mean you have a worn alternator brush. Not sure how far back they were wired this way.

 

[inxs]

- yellow from the alternator goes back to the XS2 and the introduction of the e-start

 

[XSLeo]

Yes, The yellow wire has been there from the start of electric starter.
On the later models the safety relay also turned the headlight on.
When your alternator stops working the safety relay won't get tripped. The yellow wire won't have the juice to trip the relay.
No trip-no light. So yes, a non working alternator will stop your headlight from lighting.
So when your headlight fails to light on the later models checking for proper alternator output is one thing to check before you start swapping parts.