Headlight Problem

Sean Shameless

XS400 Enthusiast
Messages
43
Reaction score
4
Points
8
Location
Ottawa Ontario
So I’ve worked through a number of little electrical issues on my 82 and am down to a headlight problem.
I seem to have traced it back to a little black plastic component under the seat.
I suspected it was a relay of sorts but when I search around on here looking at related posts I see a little smaller metal cube (which mine also has) being referred to as a headlight relay.
I understand the bike needs to be running for the headlight to get power and have tested it that way but am just looking to clarify what I might have going on and what the little box in the pic is.

Thank so much!
 

Attachments

  • 719F937F-7DC5-45DC-A0F1-89352A521DCE.jpeg
    719F937F-7DC5-45DC-A0F1-89352A521DCE.jpeg
    118.1 KB · Views: 102
The device in the pic looks like an auto-cancelling relay for the turn signals.
Yeah, thank you.
I’m starting to think I went down a weird road troubleshooting. I just heard about the diode in the harness that sometimes goes bad and causes headlight issues and plan on exploring that once I get a chance in the next couple days.
 
If your bike is an SOHC, then it is wired like my bike and the diode is pretty easy to test in-place. You need to find the headlight relay (the cube-like one with the metal cover). There are two relays that look like this - you want the one with the black, white, blue with black tracer and red with yellow tracer wires at the plug. You also need to find the rectifier on the battery box which has three white wires and a black and a read wire at the plug.

With the bike off and the battery disconnected, use a volt/ohm meter on the ohm setting connect one lead to the white wire on the headlight relay plug and then probe the three white wires on the rectifier plug and note the readings each time. Next, swap the meter leads and repeat the test. One of the six readings you take should show close to zero ohms and the others should show an open circuit (infinite ohms).
 
My diode went up in smoke on my 81. all i did is jumped the relay and it worked.
the coil in the headlight relay shorted out and the diode acted as a fuse.
Later on i will replace the diode with one with a appropriate current rating and the relay but for now it works fine.
 
Back
Top