If you answered yes to all of the above, then I have a possible solution for you. I say possible because sometimes my method just wonít work no matter how hard you try. But I have had good luck with this so read on.
First you must determine if your ride is a candidate for this fix. You must make sure that all of the standard methods have been exhausted. You must be positive that the diodes are working and that there is no short or frayed wire in your neutral light switch circuit. There has been a lot written on that so I wonít go into much detail here. Suffice it to say, you need to check to make sure all mechanical and electrical potential problems have been eliminated.
Once you have checked everything and you have determined that the problem is the neutral switch then your bike is a candidate for the following repair. The neutral switch is located on the lower right side of the engine and is very difficult to replace if you can even find one nowadays so if this works it will save you a lot of work and some money.
OK, here is the problem in most cases if the wiring is correct. The switch is in your motor oil. Your motor oil starts collecting carbon the first time you start the engine after an oil change. So there is for all practical purposes carbon in the oil almost all of the time. Now, the contacts are opening and closing in this carbon rich oil. Now add a small amount of current and you have a recipe for disaster. Every time you shift through neutral, the switch closes then opens causing a very small spark. Spark after spark burning a small amount of carbon to the contacts.
Carbon conducts electricity. Not as well as metal but pretty well none the less. After a while carbon bridges the gap and your neutral light stays on all the time. Maybe not very bright at first but over time it gets brighter and brighter until there isnít much difference between neutral and other gears. Bring out the black tape.
Now, itís time to attempt a repair. First of all check the wiring to the switch across the top of the engine. If it is shorted then my approach will not work. Now your wiring is in good shape and the diodes are working the way they should. Here is what you need to do:
Remove the battery cover and the left false tank cover to expose the connector block. The connector you want to access is the white one that is the bottom connector on the back side of the main junction box. Unplug the lower white connector from the connector block.
Inside the connector, the part you just removed, are five pins. One connector is by itself. This is the contact we will be working with. Now using a test light, clip the test lead to the positive terminal on the battery and touch the other end, the test probe, to the single pin in the connector you removed earlier.
The above photos were taken of my 1979 Goldwing. Blake Voorhees sent me the following photo of his 1976 Goldwing. The plug on his is located under the tool box just to the front of the carburetors on the left side near the frame. I canít verify the exact location for each year but this should give you an idea where to look for the earlier bikes. The main thing to look for is where the wire comes up from the neutral switch on the engine. It can be traced up from the right side of the engine near where the rear break foot pad is located.
Shift through the gears and note if the test light acts just like your neutral light. It should. If not, then stop here, you have an electrical problem that must be fixed by repairing the electrical system using conventional methods.
OK, your test light acts just like the neutral light, good. Now it is time to attempt to repair your switch. What we are going to do is burn off the carbon on the switch contacts. Depending on how much carbon buildup and the condition of your switch your results may very. You need to know that there is a possibility of damaging your wiring. You could start a fire and there is a remote possibility of causing an explosion inside the crankcase. These possibilities are rare in my humble opinion but you have been warned.
For safety sake, only proceed with a cold engine. You might want to open the oil filler cap on the engine and blow some fresh air into the crankcase. This will minimize the risk of an explosion to almost zero. I didnít do any of the above except that my engine was cold. But then I like to live on the edge. Proceed at your own risk.
What you need to do is cause a larger amount of current to flow through the switch when it is open. Note OPEN. Shift your transmission into gear, any gear, it doesnít matter just make sure you are not in neutral. In neutral, your switch is supposed to be closed and the light is supposed to be on. If you leave the transmission in neutral high current could burn the switch or wiring and may destroy something and it could start a fire on your motorcycle. Please make sure you are NOT in neutral.
Now we must make a connection between the positive terminal on the battery and the terminal to the switch. There are options here and it will depend on what you have available on hand. The preferred way is to use two wires with clip leads and a head light or fog light or some other heavy duty 12 volt device in series. You could use a solid wire with an auto fuse in series instead if a light. Use a 5 amp fuse.
Hook up one wire to the terminal to the neutral switch. Check again that you are indeed in gear. Then connect the other end to your load device (Light or fuse). Connect the other wire to the second terminal on the light then touch the other end to the positive on the battery. Only takes a second. If the light lights up or the fuse blows, you will not be able to proceed. Your switch or wiring is shorted. Verify the wiring is OK, if so then you must replace the neutral switch. Sorry.
Now itís time to test the switch to see if it worked. Remove the wire from the positive terminal on the battery and using your test light check the operation as before. The test light should now come on when you shift into neutral and go off when you shift into gear. If so, congratulations, you had an easy one. Re-assemble your ride and enjoy
That is the way mine went. I was lucky. However after about twenty or so miles the light started coming back on, dim at first but getting brighter all the time. I came home and flashed the switch again and it has worked correctly now for about three thousand miles at the time of this writing. I hope yours will be that easy.
I have a friend with the same problem but his is resisting the fix. It works to a point but wonít stay fixed. His will extinguish the test light until we shift through the gears then it goes right back to staying on. It does seem a little dimmer but on none the less.
What is required here is an increase in current to enable the carbon to burn off each time he shifts through neutral. There are a couple of ways to do this, the simplest way would be to acquire a turn signal (1156) or tail light (1157) bulb and an appropriate socket. If you are using tail/stop light, such as an 1157, then you will want to use the stop light filament. Hook up one side of the light to the positive on the battery and the other side will need to be spliced into the neutral wire going to the neutral switch. Now place the light inside a metal box of some type to hide the light. Be sure you insulate the light socket so that it doesnít short out.
Another cleaner option would be to acquire a 10 Ohm 25 to 50 watt wirewound resistor. A 25 watt will work but a 50 watt would be better able to handle the current. A couple of choices from Digi-Key would be a mountable resistor in an aluminum case their part number 850F10R-ND $6.25 or a ceramic resistor part number FVT50-10-ND $5.02. Either of these resistors could be installed instead of the light bulb. Another option would be one of these load resistors from Velocity Destriburating, Inc. The resistor can be hidden away where heat from the resistor wonít bother anything and it wonít put out light to distract you. Install the resistor or light then re-assemble the bike hiding the resistor or light bulb under the tank cover or in front of the air box.
Your neutral light should be working properly now. After a while the carbon on your switch should burn off and the extra load will no longer be necessary. Once in a while you should remove the extra load and test for proper operation. If the neutral light is working properly then you can remove the bulb or resistor. You should keep them as they may be needed again, after all, the problem developed within the switch before. I guess Iím a pessimist.
I hope this works for you. It has for the two bikes I worked on. Now I donít have that green light starring at me when I ride after dark. Be safe and happy riding.