Neutral Light Intermittent...Possibilities?

[Ben_Carufel]

My bike hadn't been ridden in a few years until I purchased it a few weeks ago. I took it for its first substantial ride today -- about 15 minutes around town. The neutral light hasn't been working at all, but after 10 minutes or so it started to work. When I went back out to it a while later, the light was inop again.

Could it be temperature related?

Where should a guy start looking to troubleshoot the thing?

Hoping someone here has some quick tips (searched but couldn't find anything conclusive) before I break out the Clymer...

[Bob_Roller]

There's a two wire connector on the left side of the bike, somewhere around the battery/side cover .

It should have a brown wire with a black spiral band and a brown wire with a green spiral band .

The brown/black wire is the wire to the neutral switch .

Take a piece of bare wire put it in the connector for the  brown/black wire, then touch the other end to bare metal on the engine or transmission .

With the key turned to the run position, the light should come on if the wiring and bulb are good .

You can check the switch by putting one of the leads of a multimeter set to the ohms scale to the brown/black wire, put the other lead to bare metal, with the transmission in any other gear than neutral you should have an open circuit, with the transmission in neutral you should have continuity, or next to 0 ohms .  

The ground wire for the neutral switch should end at the lower left transmission bolt, check to make sure this wire is not broken .

The neutral switch is not a great design and fails frequently .

[nhmaf]

It is not uncommon for switches on bikes that aren't ridden / stored along time, especially with no/infrequent gearbox oil changes, to have "balky" intermittent neutral switches.   If the operation doesn't become consistent after a few weeks of regular use and oil change, then it is indeed time to plan a replacement.

[unibober]

Neutral switch would be my guess as well as I am replacing one now as we speak. Check to see if it is weeping tranny oil as well.  Easy fix.

[Ben_Carufel]

Thanks guys. I'm again humbled by your knowledge and willingness to share it!

[montmil]

Confirm that the neutral indicator bulb is making good contact within its holder and that there is no corrosion on bulb contacts and socket interior.

Monte

[tvrla]

Those are all the points I'd have recommended. After sitting a couple years corrosion builds up and more voltage is needed to overcome the increased resistance, if at all. You'd be well advised to go through all of the connections on the bike and ensure they're clean and bright. Especially those for the ignition and charging system - at the diode board, alternator and coil. When re-connecting them, smear on a little silicon grease to help keep out moisture and prevent future corrosion.

[Semper Gumby]

The Ground attach point is a ring connector around a bolt that connects the tranny to  the left hand side of the case in front of the shifter.  Follow the brown wire back -- there is a BMW two pin connector that also needs to be checked for corrosion.

Good luck.  Persistence pays off in these matters.  Become one with your wiring diagram.   8-)

[montmil]

 Become one with your wiring diagram. 8-)

Ooh... The Borg collective. Or perhaps Caddy Shack. You funny, Gumby. [smiley=thumbsup.gif]

Monte

[Justin B.]

My '81 R100 did the same thing, it was the switch gummed up internally.  After a couple months it worked fine...

[Ben_Carufel]

Well, I dropped off the tach and speedo today at Foreign Speedo for rebuilds. Once they're back I can troubleshoot the neutral light. I'm hoping it "comes back" with use.