Headlight Relay Part Number

[d0wn5h1ft]

Hello All,

I just bought a 1981 XS400 about a week and a half ago. I rescued her from a parking lot, got the engine running, and took care of a few cosmetic issues. The problem I'm having now is that I think that the relay controlling the headlights is bad. I came to this conclusion having searched through the forums for posts about similar issues. The headlight is receiving no power (I put a voltmeter across the connections with it running since everyone said that it is supplied from the alternator). I measured the voltage across the white wire going into the headlight relay and with the bike started it did read the appropriate voltage for the rpms.

I have taken a look at the wiring diagram but I can't seem to figure out for the life of me what the part number is for the OMRON relay I need to replace. The part number on the one I have is too faded to read so that's not much help. I have heard of other people replacing them but I have no idea what to search for or where to buy it. I've tried google searches but nothing that yielded any definite results (just overpriced used parts on ebay).

If anyone can point me in the right direction or would be willing to sell me one for a reasonable price I would be more than grateful. It would be really nice to drive around past sundown without fear for my life

Edit: Or if anyone could take a look at their bike and read the manufacturer part number off for the relay I could maybe find a modern day replacement for it.

 

[arfstrom]

Temporary swap the relays. My album will help out a bit. I ordered my relays from Partzilla. and the parts came new, as a outie, when I had an innie. look at my pics, you see what I mean. 3h5. I found out that there was nothing wrong with my relay by swapping them. Mental note. Your Diode could be dead. if you look at the various wire diagrams, you will find out that the 3 white wires from the stator, one of them, goes to a diode, then that goes straight to the headlight. The relay is just waiting for the stator/voltage reg/rectifier to juice up, and spit power out. If it doesn't sense the power, it doesn't turn on the light. You can jump the to wires in the relay bunch, (pull the relay out, and put a jumper in there. (i am too tire to look that up right now, per haps tomorrow I might, or I strongly encourage you too search it out here, thats how I found out about it. My problem turned out to be the stator/Voltage reg. Stator was fine, the wires were shot. Good luck night.
http://www.xs400.com/media/albums/345/

 

[Fellow Traveler]

i too thought that the "headlight relay" was my issue and bought one off of ebay used, arfstrom alluded to the part number, when its not totally faded the casing reads omron 3h5-00, it was used on a lot of yamaha bikes for a number of years so its easy to find a used one. after i recieved one from ebay, i still had the same issue and the seller was nice enough to send me another. this one seemed not to work either and i concluded that it couldn't be that all three (the orginal plus the two from ebay) were bad. keep in mind that its not just a headlight relay, its the safety relay and is part of the charging system. i thought my relay was bad because i could bypass it and get the headlight to work, but in actuallity i needed a rectifier. because my rectifier was bad, there wasn't enough power going to the relay to activate the points and close the circuit causing the headlight to run. arfstrom's issue was of a similar nature, i recommend going through the rest of the charging system before replacing the relay.

 

[arfstrom]

So Downshift, did you ever get to the bottom of this?

My photos in the album are pretty read-able. and If I remember right, I even texted the info into the paragraph under the pic.