No headlight

pckopp

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Phil from Seattle here,
I haven't been around for a bit but I still love my XS650s. I have 3 of them now.

I picked up a 79 Special awhile back. Finally got its turn and it is a runner. There were no air cleaners when I got it and the wiring was really hacked up. Lots of masking tape and black electrical tape over poor wire junctions. The original fuse holder was gone, in its place a collection of glass fuse holders on a bunch of stray wires. It ran, but it was ugly.

The real problem was when I tried to install the air boxes. There were so many odd wires all over that when I forced them out of the way to get the boxes in place, the bike wouldn't run. Took me a couple of hours to find the broken connections and move the wiring around so the air boxes would fit. After doing that it ran fine and I put a couple hundred miles on it.

The carbs needed rebuilding so I pulled them. While I did that I ordered a new wire harness. I got the harness installed, the rebuilt carbs back in place, and it is a runner again.

Except I have no low or high beam, and no instrument lights. I do have turn signals, tail and brake lights, both controls, horn, and electric starter. It charges with about 14.3 volts above idle. Fuses are all good. I have double-checked my connections and installation. There really aren't many places to go wrong.

I am not getting any voltage on the blue wire for the instrument lights and no voltage from the left handlebar switch on either the green or yellow wire for the headlight. The headlight is good. I do not get a 'Headlight failure' light.

I have pulled the left handlebar switch assy and it looks good inside. All wires connected, clean and dry. There is the 6-position male connector, and 5 other wires from that switch. Two are the turn signal wires, two are the low and high beam wires, one is a ground.

Any suggestions gratefully accepted.
 
Do you still have the reserve lighting unit in place? The power for both the headlight and instrument lights passes through it. If you've removed it without jumpering a couple of it's wires (blue/black and blue/yellow) in the harness plug, you've broken that connection. The power for those items originates on the blue/black wire coming out of the safety relay so check that one too. But it should only put out power when the engine is running and the alternator is sending out a charge.
 
Quick update: I believe I have a bad safety relay. No voltage out on the blue/black wire. I removed the connector and jumpered the red/yellow to the blue/black in the harness connector and I have lights. Won't crank, of course. Jumper the two red/white wires in the harness connector and it cranks.

I think the entire relay assembly is bad. The diode is open in both polarities and both coils are open. I get 110 ohms for the resistor although it looks quite burned. Not surprising given the harsh treatment the wiring has suffered.

What options are available for repair or replacement?

Thanks 5twins!

SafetyRelay.jpg
 
A lot of the guy's who butcher, opp's I mean bob their bikes, may have one kicking around.
They often list them on Ebay, maybe even in the For Sale section of this site's Classifieds.
Leo
 
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