All Cads

Author Topic: Persistent Generator Light - '68 Eldorado  (Read 971 times)

Offline joeinbcs

  • Posts: 242
  • CLC Number: 26069
  • Name: Joe Northrop
Persistent Generator Light - '68 Eldorado
« on: April 28, 2015, 03:05:11 PM »
Hey all,
I hope somebody can help me solve a Gen light mystery.
No problem until we replaced the headlight switch, removed and painted the valve covers and did a few other things.
The gen light started staying on shortly after.  Drove 300 miles and the car drove fine.  After returning home, battery (nearly new) died. Interstate charged and found no problem with battery.
Replaced the voltage regulator, replaced the alternator.  Now, the light is not on at idle, but comes on with acceleration...
Can't find any broken wires...any ideas on what to try next?
Thanks, Joe
Joe Northrop
9633 Whispering Ridge
College Station, TX  77845
joenorthrop@yahoo.com
979-324-6432

1976 Eldorado, 35K miles, one owner (before me), Firethorn/Firethorn/White

Offline James Landi

  • Posts: 2385
  • 2007 XLR
  • Name: James Landi
Re: Persistent Generator Light - '68 Eldorado
« Reply #1 on: April 28, 2015, 06:33:52 PM »
CHeck the voltage with a good digital voltmeter at the battery... with the engine running at idle, your new alternator should be charging the battery at 13.5 volts.  If not, then check the voltage at the alternator --- you may have a problem with output wire on the alternator... sometimes the wire is almost entirely "cooked" for resistance as the wire ages. Connect one wire from your voltmeter to the alternator output lug and the other to your battery.  There should be NO voltage... if there is, the stupid output wire is your problem!   It's happen to me... the wire looks fine, but the wire terminals are toast(ed)... James

Offline joeinbcs

  • Posts: 242
  • CLC Number: 26069
  • Name: Joe Northrop
Re: Persistent Generator Light - '68 Eldorado
« Reply #2 on: April 29, 2015, 11:34:03 AM »
Thanks, James...I'll try that!  Joe
Joe Northrop
9633 Whispering Ridge
College Station, TX  77845
joenorthrop@yahoo.com
979-324-6432

1976 Eldorado, 35K miles, one owner (before me), Firethorn/Firethorn/White

Offline joeinbcs

  • Posts: 242
  • CLC Number: 26069
  • Name: Joe Northrop
Re: Persistent Generator Light - '68 Eldorado
« Reply #3 on: April 29, 2015, 04:11:43 PM »
I got a reading of 14:45 at the battery, and a reading of between .05-.09 when connecting the positive output on the back of the alternator to the positive battery terminal.
Does this sound like a wire issue?
Joe Northrop
9633 Whispering Ridge
College Station, TX  77845
joenorthrop@yahoo.com
979-324-6432

1976 Eldorado, 35K miles, one owner (before me), Firethorn/Firethorn/White

Offline James Landi

  • Posts: 2385
  • 2007 XLR
  • Name: James Landi
Re: Persistent Generator Light - '68 Eldorado
« Reply #4 on: April 29, 2015, 07:03:48 PM »
With 14.5 at the battery, you're charging!  DId you get that reading at idle with no load on?  If so, take a reading with the head lights on and the a/c cranking... your voltage should read around 13.5 with that kind of load on the alternator. When you do this, check for heat at the output terminal nut on the alternator.  BE CAREFUL, it could be VERY HOT  (a little spit on the fingers is a good idea).  Intensive heat equals a weak connection, and at this point that is something you're exploring.   ALso, is the "tell tale" light out now on the dash? I keep thinking that your issue may be a bad wire from the ALternator output to the battery, and this might just show up when you have an electrical load on the battery and alternator .  (I had this issue with my '72 convertible... After I purchased a new alternator, and was about to disconnect the old one, I burnt my fingers at the output terminal of the old alternator... the wire cooked just enough to offer high heat and resistence only when I was driving at night with the lights and a/c blowing...   James

Offline joeinbcs

  • Posts: 242
  • CLC Number: 26069
  • Name: Joe Northrop
Re: Persistent Generator Light - '68 Eldorado
« Reply #5 on: May 01, 2015, 10:26:38 AM »
James, Here are a few other details that may be important.  The Gen light does not come on when I turn the ignition switch to either ACC, or ON, only after I start the car, and only then when I rev the engine.
None of the other idiot lights come on either...not sure which if any should?
Joe Northrop
9633 Whispering Ridge
College Station, TX  77845
joenorthrop@yahoo.com
979-324-6432

1976 Eldorado, 35K miles, one owner (before me), Firethorn/Firethorn/White

Offline Scot Minesinger

  • Posts: 6004
Re: Persistent Generator Light - '68 Eldorado
« Reply #6 on: May 01, 2015, 11:29:45 AM »
I have a similar problem on a 72 Eldorado with an internally regulated alternator, where it charges 14.5 volts and generator light on dash is on.  Got to be a short somewhere and when I find it will post what happened.  Should be starting this rich enjoyable experience Monday night, and will report back when I find it and what it was.  In the mean time if you find it, let me know as well so that maybe I will finish it Monday night.
Fairfax Station, VA  22039 (Washington DC Sub)
1970 Cadillac DeVille Convertible
1970 Cadillac Sedan DeVille
1970 four door Convertible w/Cadillac Warranty

 

Sitemap 1 2 3 4 5 6 7 8 9 10 11 12 13 



All Cads