"Gen" Light Out

[Dave 2]

Hello, I have not been on the forum for some time, however I have continued to read the technical forum. The other day I noticed that the Gen. Light (Red) was not on when I went to start it up. It started and I drove the 20+ miles home. At home I still did not have a light when the key was "on" but the engine not running. I charged the battery which got it to 12.95 volts from 12.45 volts. I then again had no light when I turned on the key, and after I started it and brought the engine up to about 4,000. RPM I still had no light.

I have reviewed just about all the content in this forum, so I am aware that I need to begin a methodical testing of the entire charging circuit. I have not noticed that any of you have had this same problem of NO light. So my two questions are; does anyone have a sense of what may be faulty, and is there a straightforward way of determining if the bulb is burnt out? From what I can tell from my Clymer Manual it is a significant process to get at the bulbs.

I have a 1983 r65LS with 14000 miles on it.

Thank you for any suggestion that you may have. Dave

[Bob_Roller]

With the instruments being covered by fairings, my suggestion would be to perform a test of the light bulb circuit .

You need to remove the front cover of the engine to gain access to the alternator.

Remember to remove the negative lead from the battery before removing the cover.

After reattaching the battery cable, with the key in the 'ON" position, place a metal object between the two slip rings on the alternator rotor .

If the bulb and wiring to it are good, the "GEN' light will come on .

If the light doesn't come on, you need to get to the light bulb and check it for continuity and security in the socket, it's a 'wedge' type bulb, not a great application in this case .

There's a 'fix' for the bulb going out, it requires you to connect a 330 ohm resistor between the two wires for the 'GEN' light somewhere in the wiring harness .

If the bulb and circuit test good, most likely problem is with the rotor .

[nhmaf]

+1 what Bob said - or, you could just dive into the gauge cluster and get to the bulb to check it first, but may be easier/quicker for most people to pull the front engine cover first to do the slip ring jumper check, plus, you'll be able to give things a visual check under there too.

[Dave 2]

Thank you for your replies. I'm teaching myself basic electronics as I go through this process, so it will take some time as I take your suggestions and then apply them.    Learning is an adventure.

[Justin B.]

All of my "no gen light" issues have been open rotors...  

[Dave 2]

Thanks for your response, and if you will pardon my inexperience what is an open Roter, as compared to a functional roter, David :-/

[Bob_Roller]

Open refers to the windings (wire) in the rotor, if there is a break in the wire you have an 'open' circuit, the rotor is useless, it's a fairly common failure with the airhead bikes .

[montmil]

Open refers to the windings (wire) in the rotor, if there is a break in the wire you have an 'open' circuit, the rotor is useless, it's a fairly common failure with the airhead bikes .

... so you will be using the DVOM to check for electrical continuity between the slip rings. The slip rings -the shiny, coppery-looking thingys where the brushes ride on- should register a complete circuit, ie: needle swing. No needle movement, the circuit is "open", ie: broken wire.

Hope this helps you, Dav.

[Dave 2]

Hello Thanks again for your help. I just checked for continuitywith my multimeter between the slip rings and there is continuity. So at this point  I guess the rotor is good .Bob I also used a non-powered test light to cross the two slip rings with the ignition on but nothing changed, Ie the Gen light remained off. Are these two results what you could expect or have I messed up? If not I guess that I now need to test the voltage regulator and the diode board and if those check out I will need to pull off the "nose cone" to get at the instrument cluster. Does this sound right? Thanks, David    P.S. nhmaf, I hope Irene did not cause you any flooding or power outages. Bar Harbor had minimal wind damage.

[Bob_Roller]

When you check the slip rings on the rotor, you need to place a piece of paper between the brush and the slip ring .

Otherwise you may be seeing the resistance of the voltage regulator .

The only two items that will cause the "GEN' not to come on are an open "GEN' light circuit (bad bulb or broken /disconnected wire), or an open rotor .

My guess is that the bulb is burned out .

[tvrla]

Think of the charging circuit like a flashlight: the light bulb needs electricity to it and a return path - a ground.  

The ground is through the rotor then to the frame.

Power comes through the ignition switch, kill switch then to the charge light.

When you short the two alternator brushes together you're bypassing the rotor to ground. It's taking the rotor out of the circuit and connecting the ground directly to the light. If the light doesn't come on then you know the rotor isn't the fault, though it could still be faulty.

At that point you'll need to check out the light bulb. The only difficulty with that is removing the aluminum ring around the ignition switch that holds on the black plastic wind screen. You really should have a tool for that - I made mine out of a piece of hardwood with pins sticking out.

Once in there, check out the bulb. If it's good, check that it's getting power. If not, then check the kill switch and ignition switch.

[Dave 2]

OK, I'll check the rotor with the paper and then I guess I'll get to the gen light. Thanks for the help I'll let you know how it turns out

[Dave 2]

Hello, The rotor checked out with continuity and a OHM value in the right range I now have removed everything necessary to get at the tach, (1983 R65LS) The rear of the housing is held in place by 3 screws which I have removed and there is a round (harness jack) connecting through the middle of the housing. I can not get the back cover off. It is loose all the way around but it will not seperate more than 1/8 inch. I have tried to unplug the harness jack but it won't budge. My tendancy can be to just use more force only to find that I have damaged something . I thought I would ask any of you who may know what to do at this point. Am I missing something or is it time to just use more force? Thanks, Dave

[Bob_Roller]

The connector has to come off to get the cover off .

No 'gentle' way to get it off, you may want to try spraying something on the lines of WD40 onto the backside of the connector, then take a pair of pliers on the backside of the connector, in line with the wires and try to move the connector a little bit, rock it back and forth with a little pressure, you're dealing with a 30 year old plastic connector .

Not available if it is broken beyond use .

[Dave 2]

Thanks Bob, That is just what I wanted to know. I will use care. Dave