News:

Due to a technical issue, some recently uploaded pictures have been lost. We are investigating why this happened but the issue has been resolved so that future uploads should be safe.  You can also Modify your post (MORE...) and re-upload the pictures in your post.

Main Menu

1966 Cadillac Generator Light

Started by RandyK, June 07, 2015, 08:05:53 AM

Previous topic - Next topic

0 Members and 1 Guest are viewing this topic.

RandyK

Re 1966 Cadillac Convertible:  When I turn the car off the generator light remains on. Any info would be appreciated.
Randy (Texas)
RandyK

Scot Minesinger

Does generator light illuminate when car is running?  If so what is voltage at battery with car running (should be about 13.7 or so)?  What is battery voltage with car off (should be about 12.6 or so)?  The way it should work is when car is in run position, but not started yet, the gen light should turn on and then turn off when car starts.  Does it only turn on when car is off?  Do you have the shop manual with wiring diagram? 
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

RandyK

The generator light stays on after the car is turned off. Battery is good and at good levels.
There is a wire/clip that goes into the back of the generator.  When I unplug that the light goes off.  The wire looks like it goes to the regulator.  Wondering if regulator or alternator is bad.
RandyK

Scot Minesinger

The idea that the battery is good to me means you have no charging issues in that alternator and voltage regulator are good.  If the voltage regulator or alternator were bad the battery would die.  The voltage regulator could be over-charging, need to verify that is not happening. 

When car is off and in run position the generator light is on.  Then when car is started it goes off provided charging system is healthy.

I think you need to look for a short that allow the generator light to be on when car is off, probably in the ignition switch.  This is a tough one to diagnose over the internet.   
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

James Landi

Scot may be right about your ignition switch being faulty.  The generator light is connected to the ignition switch (and postive side of the battery) and the other side of the bulb goes to the "Field" connection on the regulator.  So, that light should be off when the ignition switch is off. I can't think of a situation where the regulator could "back feed" that bulb if the switch were working properly.  Have you tried playing with the ignition switch, cycling in on and off with the engine off?  Does the radio stay on with the ignition switch in the off position?  James

Glen

The picture below is from the 67 shop manual.  I would imagine the 66 is comparable.   
Glen Houlton CLC #727 
CLCMRC benefactor #104

curly

Glen has the answer, you have a bad diode in the alt.  Rebuild or replace.

T Lewis