Neutral light

[redglbx]

So, I know this has been discussed some somewhere but quite frankly I can’t remember what causes or fix’s the problem,

On my 76 wing it has started to have the neutral light come on when the clutch is pulled in, it is properly on in neutral but also comes on every time the clutch lever is pulled in, never done this before. Thoughts, ideas ?

[Sidecar Bob]

It sounds like the diode in the neutral light/starter disconnect switch circuit has failed.

As you probably know, the starter motor is not supposed to be able to run when the engine is in gear unless you disengage the clutch (it will start if the clutch lever is pulled no matter what gear it is in). Two circuits are involved in that:
1) The starter disconnect switch (in the clutch perch) interrupts the starter solenoid circuit between the solenoid and ground, preventing it from being energized unless the clutch lever is pulled.
2) The neutral switch interrupts the neutral light circuit between the light and ground.

The diode is connected between the neutral light circuit and the starter solenoid circuit so that the neutral switch bypasses the starter disconnect switch but the starter disconnect switch has no effect on the neutral light.

Diodes can fail in 2 modes, open circuit (no continuity) and short circuit (zero ohms). If the diode has failed in short circuit mode the neutral light will come on whenever you pull the clutch lever.

[Pony Ruiz]

I had that problem. Swapped out the diode. Fixed.

[redglbx]

So where can I buy a diode, parts-n-more lists a clutch switch diode p/n 31710-371-008 ,$12, is this it ?

Any suggestions on where it’s located in the bike ?

By the way guy’s, thanks for your inputs.

[Sidecar Bob]

Radio shack. Just about any 1A rectifier diode will do. Just slip some plastic tubing over the leads, crimp on a couple of of suitable lugs and plug it into the connector. If you plug it in backward the neutral light will still come on when you squeeze the clutch lever so just plug it in the other way.

[Fred Camper]

Check out swapping one of the lighting diodes first. If you do not have a reserve lighting unit anymore, then the swap can be permanent as the bypassed RLU no longer needs a diode.

[pidjones]

So where can I buy a diode, parts-n-more lists a clutch switch diode p/n 31710-371-008 ,$12, is this it ?

Any suggestions on where it’s located in the bike ?

By the way guy’s, thanks for your inputs.

I've purchased used on ebay and new from Partsnmore. Both seemed fine. These captures from the FSM show which and where (you really need a FSM):

Screenshot_2020-06-08-07-18-30.png

Screenshot_2020-06-08-07-18-48.png

[redglbx]

Thanks PID, I learned something here, I have multiple shop manuals but they are up in my shop and that would require some effort things have just been a bit crazy here lately, this should be an easy fix. Hope to report back today ! Again thank you !

[redglbx]

PID, thankyou very much, easy peasy fix once I seen your pix and realized what it was, took longer walk to the shop to get a spare than it did to fix it ! thanks again for the help!