Headlight Woes 78 xs1100

[angelican]

Tis the season to ride...only if the headlight worked! No pwer @ harness to fairing, took the relay out and jumped bl/blk and yel/red still no pwer Fuse good, left side @ hi-lo switch seems ok. I'm at a point of running pwer lead with a toggle from battery, any other thoughts... maybe a flashlight strapped to helmet

[debauchery]

got a 9v battery ? set of jumpers with alligator clips or something ? jump power from the battery directly to the headlight (high or low is ok) does it light up ? (bike runs right? but no headlight at the moment) try jumping it to the light and post back

[DGXSER]

Its the simple things in life

that often confuse us. I had all kind sof issues gettign ym headlight to work correctly. I jumpered out the RLU as well as the relay ( you did not mention the RLU so you may want to try jumping that out). But in the end, I discovered that even though BOTH of the headlights I had the bulbs LOOKED good, in the end, both were busted. New bulb and I had a nice functioning headlight!!

[debauchery]

that often confuse us. I had all kind sof issues gettign ym headlight to work correctly. I jumpered out the RLU as well as the relay ( you did not mention the RLU so you may want to try jumping that out). But in the end, I discovered that even though BOTH of the headlights I had the bulbs LOOKED good, in the end, both were busted. New bulb and I had a nice functioning headlight!!

i was heading there but waiting to hear if that was in fact the situation , sometimes it is simple ,other times its not. can't wait to see what turns up

[angelican]

elimination process

I suspected the bulb early on so failing to mention, I took the bulb out and jumped it to a 12 volt source and the bulb works fine. I'm using a replacable bulb rather than a sealed beam! Not sure how to jump out the RLU, my thoughts are leaning to the ignition switch? although the white light on the instrument panel did not indicate /No headlight. Voltmeter check @ headlight relay(absent) is nothing for power?

[debauchery]

I suspected the bulb early on so failing to mention, I took the bulb out and jumped it to a 12 volt source and the bulb works fine. I'm using a replacable bulb rather than a sealed beam! Not sure how to jump out the RLU, my thoughts are leaning to the ignition switch? although the white light on the instrument panel did not indicate /No headlight. Voltmeter check @ headlight relay(absent) is nothing for power?

with the circuit assembled with bulb(known to be good) you should be able to find available voltage up to the drop (light don't work=no load) grounds are good? you could try jumping the ground out/off the headlight to known gd ground(battery - terminal) this would at the least remove a ground error.
if the light turns n with the ground jump *ding problem solved(find the fail in ground side of circuit)
if it fails to illuminate ,with it conected as mentioned do you have available voltage @ the light power lead in?
any short to ground before the light would create a open without load (lets the magic smoke out)
fyi a relay has a low amp side that creates the field that allows us to operate a high current circuit with low current...define absent please?

[crazy steve]

You're jumping the wrong wires at the relay; the yellow comes from the alternator, the black is ground, and you need to jumper the red/yellow and blue/black. This should immediately turn on your gauge backlights, and sends power to the RLU. If no headlight is hooked up, the 'headlight' light should come on. You should also have power at the blue/green and blue/yellow wires at the RLU. These then go to the handlebar 'hi-lo' switch, and from there to the headlight. When you change the switch, the high beam indicator should change. If not, (and if you haven't already done so) remove/disassemble/clean the hi-lo switch. Also check the connections where the handlebar switch plugs into the main harness. If the high-beam indicator and headlight fails to light at this point, the RLU has probably failed...

There's quite a few errors in the early wiring diagrams, and the lighting circuit is one of them...

[yamahansolo]

Even the one link on the site is wrong for 78 and 79. I had alot of headlight issues until I searched and found the correct set up the bypass that works on the newer ones wont work on the 78,or 79. It lets both dim and bright be on at the same time. I burned through quite a few bulbs before I found out ...