[paynetothemax]

Hi All,

My '81 Honda CM400E has an annoying problem where the headlight won't turn on. The bulb is fine (plugged it into battery and it lights up), all other electrical components are fine, except for the blue high beam light on the dash, which doesn't come on even if I fiddle with the highbeam switch. I checked the power to the headlight plug with a multimeter and it is getting 12 volts. What could be the problem? How is the bulb plug getting power but not the headlight itself?

Additionally, the first time I noticed this issue it was dusk and the headlight was out, but then turned on halfway through the ride, but then the next time I started it, it was out again and has been since.

I hate electrical problems.

 

[mike in idaho]

Check the ground wires.

 

[paynetothemax]

Check the ground wires.

On a visual inspection they looked fine but I'll try to unwire them and rewire them to see. The green wires are connected to the brackets that hold the big connectors in place as they should be I assume

 

[mike in idaho]

Those "brackets" aren't grounded, the wires on them are used to ground the turn signal stems by plugging into the green ground wire in the main harness.

 

[paynetothemax]

Those "brackets" aren't grounded, the wires on them are used to ground the turn signal stems by plugging into the green ground wire in the main harness.

Where can I even check the ground? Am I going to have to take the whole motorcycle apart? I see based on the wiring diagram that the headlight ground goes through a bunch of connectors and back to the main frame ground but the headlight is the only thing not working, so is it possibly one of the connectors in between the frame ground and the plug? All the connectors looked fine inside the headlight housing.

 

[mike in idaho]

Put your test light clip on the positive battery post then probe the ground wire connections, if it lights up the ground is good.