headlight problems

[alwaysworking]

hello smart people!
I'm new here (will post introduction when I'm not at work)

I'm having a problem with my headlight, sometimes it comes on sometimes it doesn't. I've been searching around on here and see quite a few people talking about bypassing the RLU (?). this sounds like it might be a cure to my problem but I can't find a thread simply explaining how to do this (in idiot proof terms).

can someone explain how to bypass te RLU pretty please?!? I have to ride my bike home from work in a few hours and I'd like to see the road!

oh p.s. it's a 1975 xs650

thanks on advance!
-Daniel

 

[XSLeo]

They didn't start using the RLU till 77. Your 75 won't have one. On your 75 the headlight gets power through the on/off switch and hi/low switch. The contacts inside the switches get dirty. You can carewfully disassemble and clean the switches. Bright and shiny is a goog thing. A tiny bit of dialectric grease on the contacts will help keep them clean. Same with all the wiring connectors in the headlight circuits and the rest of the elecgtrics.
If you look through the eletrical diagrams listed in the tech section you will find one for your bike.
Leo

 

[alwaysworking]

hmm, well my bike must be a mutt then because I definitely have the grey box under the seat marked headlight relay. I've been reading as many posts as possible regarding this box and I am still unsure on what exactly to do, can someone tell
me which wires I need to connect to each other to bypass this sucker?

thanks!!

 

[Grinder]

From what I've read it's blue/yellow to blue/black and just unplug it. Use the search function and type RLU and you get lots of info. Like Leo said 75's didn't have those. I thought it said reserve lighting device on the box but it's been awhile since I threw that sucker out, is that what yours says?

 

[alwaysworking]

oh it does say reserve lighting device.. should I disconnect/bypass that?

thank you.

 

[GBGRIDER]

You guys are missing something really simple. I see this problem a lot at my job, how old is your headlight? When lights start to go bad and you hit bumps or vibrations from your bike will turn them off and on. Try hitting the light with your hand (not too hard)and see if it flickering then you know the problem. If not do what the rest said to do they are all valid points

 

[alwaysworking]

ok ok, so I tried the deal where you connect a jumper cable from the battery to the blue/yellow wire and my headlight comes on just fine, but when I connect the blue/yellow wire to the blue/black wire I get nothing. I have been reading and trying to figure this out but I am stumped and feel very dumb right now. does anyone have any ideas or tips or tricks to use so that I can get my headlight working?

thanks!!

 

[Grinder]

If your bike has a headlight on/off switch, the blue/black wire comes from that. That wire should have 12V with the key on. Check it at the plug by the RLU. If it doesn't you may have a problem with the headlight on/off switch as Leo suggested. Thats why jumping the blue/black and blue/yellow should bypass the RLU as it's sending 12V directly to the blue/yellow wire without passing through the RLU. As you said it works when you give that blue/yellow wire 12V. A simple fix would be to connect the blue/yellow to a switched 12V wire(brown). Your light would then work with the key on but your headlight on/off switch wouldn't work.

 

[alwaysworking]

A simple fix would be to connect the blue/yellow to a switched 12V wire(brown). Your light would then work with the key on but your headlight on/off switch wouldn't work.

thank you SO much!!!

 

[keyboard331]

I was going to do the same thing(remove RLU) to solve a chronic problem of blowing headlamp fuses. I thought first it was a short in the hi-beam switch wire, and used only low. After low started going I went to remove RLU and when I loosened the 2 bolts and lifted up, some wires were bare in the metal cage underneath it! Taped up good and haven't had a problem since.