My 77 is just about road ready. Generator is shot, reg is shot, putting on a brand new generator &amp\\; regulator. I replaced 90% of the wiring, which looked like heck. My question is do I need a gen light, and if I do, how do I wire it to "stand alone" if you know what I mean? I heard somewhere that you need to put a diode in the line to it.
Any thoughts would be appreciated.......

 

You might need a diode if you had an alternator, but since you have a generator this is not the case at all.
&nbsp\\;It is a good idea to include a generator signal light, just as it is to have an oil signal light.
&nbsp\\;The gen signal light uses a 4 candle power bulb.
Basically you wire this up starting at the voltage regulator terminal marked 'Gen' or 'D+'.
Run the wire to the generator signal light bulb center.
Off the bulb metal base run a wire to connect with either of these points:
the oil signal light wire coming from the accessory breaker
the front stoplight switch
the horn switch
&nbsp\\;Any of these will work.
Make certain the generator signal light is not grounded ! You check this by removing the wire from the regulator 'Gen' or 'D+' terminal (but leave the wire connected that you just ran to the gen sig light) and place the removed wire so it does not touch anything.
&nbsp\\;Then turn the ignition on and if the gen sig light comes on the light is grounded. This has to be fixed.
If the light does not come on, then all is OK and the light is not grounded. Proceed and be sure to flash the fields after all of the wiring has been connected before starting the engine. I have included a wiring diagram for you to follow as you read my description of wiring in the light.....pg


[IMG]local://upfiles/8331/525FD623FB4D4FB7A635DBC50FCE8CD3.jpg[/IMG]

 

For some odd reason Harley did use a diode on the'78 - '81 Sportsters and it is wired into the generator and oil light. My '81 has this and it's located in the headlamp bucket. One of the lead wires broke off once and I bypassed the diode and both lights worked ok, but I decided to put a new one back in line anyway.

 

Mojo......
&nbsp\\;There I go again wiping egg off my face! Won't I ever learn to leave 1975 and later comments to others?
Probably not, so thank you for the correction.
I wonder what the purpose of using a diode was? I think of a diode as a check valve, (right or wrong?) but can someone give me a better idea of what a diode does and how it works in a generator circuit?
pg

 

A diode in all electrical circuits lets current flow in only one direction. One end is the cathode and one end is the anode. That's about the extent of my knowledge on them. Since one end of the gen. and oil light is connected to the main circuit breaker, maybe they were put in line to prevent damage in the event of a short to ground on the the armature or field on the gen., or the connection on the oil sender switch, although it would seem that the circuit breaker would handle it. I'm trying to dig up more info on the reason HD installed these, and will post with more info for anyone interested.

 

Ok, here's the reason for the diode in the charging circuit: The diode prevents current flow from the battery into the regulator and generator, but permits charging current to pass from the generator to battery and load. Info quoted from HD service manual.

 

Thanks Mojo.
&nbsp\\;I thought a diode acted like a check valve, and you just confirmed that. Also appreciate the explanation. I know if the signal light were to develop a ground condition, the generator will not produce until the ground is corrected. Maybe the diode was installed to prevent that?......pg

 

That's exactly why they were put into the charging system wiring. A short at the signal light or wiring to generator would cause failure to charge and damage to the newer solid state regulator. Weird huh? Old tech generator and new tech solid state regulator.

 

Thanks guys, I knew you would point me the right way!!!!
&nbsp\\;
Trying to come up with enough extra to say the heck with the Gen\\; and go to an alternator set-up. J &amp\\; P has the alt conversion for 460.00, there is a guy on e-bay converting small car type ones with a plate for 380.00........