ST1100 Headlights

Took my 2002 ST out today and the headlights will not go on no matter what I try. I looked at the fuse in the box on the left side of the bike, took out the bulbs and they are good, I can't seem to figure it out. All of the other lights work, any ideas?

flick the starter switch a few times, it has a headlight cutout feature that could be causing the problem, and is the most likely cause. Next on the list would be to toggle the high/low beam switch, there are headlight relays that sometimes stick.

Tried both of those and still no power to the headlight sockets.

I would get a simple test light and see if you are getting power to the headlight sockets. Then the next step would be to see if you are getting power to the switch. That would at least narrow the focus of the problem. Then test the wires from the 'problem' to the socket or back to the fuse.

also check the fuse with a multi-meter to make sure there is continuity. Sometimes they can look good but be open. Like UP said start tracing out the path, you may also have some corrosion that's causing a large voltage drop under load.

Uncle Phil said:

I would get a simple test light and see if you are getting power to the headlight sockets. Then the next step would be to see if you are getting power to the switch. That would at least narrow the focus of the problem. Then test the wires from the 'problem' to the socket or back to the fuse.

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Always test the tester first. There are few things more frustrating than testing with a burned out bulb (neon or otherwise) in a tester. Make sure this works or use a muti-meter - and again, test the m-m first.

That is where i am at right now, have most of the tupperware off so I can get at the wires. There is no power to the headlight sockets, but all the gauges work and dash lights.

dwalby said:

flick the starter switch a few times, it has a headlight cutout feature that could be causing the problem, and is the most likely cause. Next on the list would be to toggle the high/low beam switch, there are headlight relays that sometimes stick.

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I've had this happen on Hondas also. The first time, I replaced the headlight bulb...natural thing to assume. Reading the wiring diagram, I noticed the cutout circuit in the starter switch...the starter worked fine, so I removed the switch assembly from the handlebar and found some severe corrosion and pitting. Had current to the switch but none passed the contacts. Replaced the switch assembly and everything was fine. No external evidence of a problem was obvious..no corrosion, no dragging/rough feel to the switch...problem wasn't obvious until I took things apart.

Fuse is good in the box on the left side of the bike, is there another fuse for the headlights other than that one?

I will take the starter switch apart to see if it looks OK.

SMSW said:

Always test the tester first. There are few things more frustrating than testing with a burned out bulb (neon or otherwise) in a tester. Make sure this works or use a muti-meter - and again, test the m-m first.

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Yeppers, that's a 'first assumption' as you have to make sure you have a good ground. ;-)

It was the starter switch, I hosed it down with electronic contact cleaner and after working it a bit it now seems to work just fine. Too bad I wasted a beautiful fall day with temperatures in the high 79's working on the bike and not riding, but at least I learned something, thanks!

IMO, the Honda starter switch (button) having a double contact to interrupt the headlights during cranking is poor engineering.

It would have been much simpler, more reliable and less expensive for Honda to have simply grounded the headlight relay winding to the starter cable at the starter solenoid.

I do this for many relay installs. That would have removed one of the most frequent failure points from the ST1100. By "frequent" the term might be referred to as "extremely rare" for other bikes. ST11's are remarkably reliable beasts, IME.

ennacac said:

It was the starter switch, I hosed it down with electronic contact cleaner and after working it a bit it now seems to work just fine.

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Could have been avoided by some small, annual service and cleansing of those switches...
Dodgy contact of the HIGH-LOW switch is also popular...

Norm said:

IMO, the Honda starter switch (button) having a double contact to interrupt the headlights during cranking is poor engineering.

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I don't judge about the engineering point, but fail to understand that "hard-wired" concept in the first place...

EC-spec STs feature a full light switch (OFF-P-ON), so before I stop the engine I kill the lights, after firing it up I turn them on... simple muscle memory, just as closing the chinstrap on the helmet, putting gloves on, retracting the kickstand, etc...

ST1100Y said:

I don't judge about the engineering point, but fail to understand that "hard-wired" concept in the first place...

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Our nanny governments require, by law, that headlights are always on, on motorcycles (and cars in Canada too), thus, we can't be left to remember such a thing on our own.

I was preparing to hit the road for a Texas to Colorado trip in a few days and was going for a little shakedown ride. Had the same problem as has been discussed and solved here. Thank you guys for taking the time to share your knowledge. I'll be looking into the starter switch at first light, and maybe the dimmer switch if that doesn't do the trick. Happy trails.