Larry Posted August 21, 2009 Report Share Posted August 21, 2009 I have just replaced the alternator and bat on my 96 deville. My driving voltage is around 11.4 to 13.2 varied. Took it to auto zone ,the system was at 13.7 at idle everything was fine.. But while driving and stoped at light in drive it goes to 11.7 or lower and I have not seen 13.7 , I hope I didn't damage the new alternator using the bad battery before I replaced it. Any thoughts, thanks, LARRY PS The computer does not say anything. I replaced the alternator because I heard noise and the voltage was 11.7 varied but would not really go up,and the lights seemed dim ,but no computer warning of any type .And after the alternator replacement, found out my battery was bad. Quote Link to comment Share on other sites More sharing options...
adallak Posted August 21, 2009 Report Share Posted August 21, 2009 Is that the voltage you see on the driver info center or one you measure directly on the battery? Quote The saddest thing in life is wasted talent Link to comment Share on other sites More sharing options...
Larry Posted August 21, 2009 Author Report Share Posted August 21, 2009 Is that the voltage you see on the driver info center or one you measure directly on the battery? as far as I can tell its similar to my digital volt meter measured on battery post, yes there may be a slight differnce, thanks, Larry Quote Link to comment Share on other sites More sharing options...
winterset Posted August 21, 2009 Report Share Posted August 21, 2009 Did you check all your grounds. Also check the resistance of the red+ cable running from the Battery to the alt. were the alternators OEM or aftermarket? - there have been discussions of aftermarket alts not performing to specs. Quote Link to comment Share on other sites More sharing options...
BodybyFisher Posted August 21, 2009 Report Share Posted August 21, 2009 I posted an extensive thread on this a while ago. Heat is the alternator's worst enemy, as an alternator gets hotter, its output decreases, it is not uncommon to see the 11.7 volts you are seeing in the summer months with the AC, lights, radio, wipers on at red lights and in traffic I will see if I can find that thread Quote Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
BodybyFisher Posted August 21, 2009 Report Share Posted August 21, 2009 See my post #10 in this thread http://caddyinfo.ipbhost.com/index.php?showtopic=11315 Quote Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Larry Posted August 26, 2009 Author Report Share Posted August 26, 2009 I posted an extensive thread on this a while ago. Heat is the alternator's worst enemy, as an alternator gets hotter, its output decreases, it is not uncommon to see the 11.7 volts you are seeing in the summer months with the AC, lights, radio, wipers on at red lights and in traffic I will see if I can find that thread THANK YOU, I think you hit it right on, it was 95 degrees and very hot. When the car first starts in the hot weather ,it was 13.7 ,but as it got hot it reduced somewhat. I replaced the alternator because it was making a noise and volts were not going up and down as much as I would like to see. This all started after a week vaction and the caddy sat at home. After getting this fixed the car overheated to the extent it wanted shut down. Of course I was out of town and my wife gives me a call on the way back from work. At this point I think it may be thermostat. I will install tomorrow. Thank you , LARRY ps. and of course my lights are on all the time when car is in drive or reverse so I know this puts more of a load on the system, alternator. Quote Link to comment Share on other sites More sharing options...
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