GEN Light always on
Thread Starter
Racer
Joined: Sep 2013
Posts: 254
Likes: 0
From: Charleston SC
GEN Light always on
My gen light in my 79 wont go off
i check the alternator and it is functioning properly.
checked the connection to the alternator and it seems to be tights.
what am i missing?
thanks
i check the alternator and it is functioning properly.
checked the connection to the alternator and it seems to be tights.
what am i missing?
thanks
Racer
Joined: Mar 2002
Posts: 406
Likes: 1
From: Maroochydore QLD
Melting Slicks
Joined: May 2011
Posts: 2,753
Likes: 119
From: Springfield Missouri
there is no generator light because you don't have a generator on the car.
It's probably a bad diode in the alternator causing this. It may still charge correctly, but it might start causing the battery to go down when not driven. The alternator can be rebuild easily and at a small price. Brushes and diodes are fairly cheap.
It's probably a bad diode in the alternator causing this. It may still charge correctly, but it might start causing the battery to go down when not driven. The alternator can be rebuild easily and at a small price. Brushes and diodes are fairly cheap.
Team Owner
Joined: Jul 1999
Posts: 65,492
Likes: 230
From: Orange Park Florida
Most likely cause is the two wired at the regulator, on back side of the alternator, are reversed.....with key off, engine still, when looking at the backside of the alternator, the whit two pin plug....-- arrangement....the one that is MOST CLOCKWISE is sometimes RED if the plug has been replaced, and the stock wiring is tough to tell the colors on as it gets old,.....now the MOST clockwise wire above should have a steady 12 volts on it, and the other one should not, when you turn on the switch without running engine, BOTH should have 12 volts on them,
if reversed, the switched voltage to one side of your red dash light passes through the bulb, and goes to the regulator at the LEAST clockwise point.....what happens is if the alt ceases to put out, the regulator will ground that wire, causing the dash light to light, but IF the wires are reversed, it's feeding the regulator sense wire and causing the light to light at least a bit.....
if reversed, the switched voltage to one side of your red dash light passes through the bulb, and goes to the regulator at the LEAST clockwise point.....what happens is if the alt ceases to put out, the regulator will ground that wire, causing the dash light to light, but IF the wires are reversed, it's feeding the regulator sense wire and causing the light to light at least a bit.....
Race Director
Joined: May 2006
Posts: 18,606
Likes: 2,542
The other thought is similar to mrvette, that same two wire plug. Corrosion on the contact, a wire broken inside the insulation,etc. Using a sharp pointed test light you have to check the voltage at those two wires.
