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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #1
Hi,
My '95 Deville is stalling out under electrical load.
Mostly stalls out when headlights are on and sometimes just braking and/or using a power window will stall it.
I watch the voltage on the dash display and it always drops when any higher voltage accessory is used----when it drops below
a certain voltage it always stalls out.
Had a new alternator installed recently and a brand new battery in hopes of solving this issue.
Had both checked today at my local mechanic and both apparently ok. No codes showing at all.
My trusted local mechanic for 7 years says he does`nt know what else it could be and he reluctantly steered me to take it to a local
GM dealership, saying maybe they have more knowledge there on this issue than he does.
I don`t like taking my Caddy`s to stealerships.
Any thoughts on what it could be?
 

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Super Moderator
White Diamond '03 DHS (with DTS floor shift)
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Was it a new, rebuilt or reman'ed alternator? What brand was it?
How about the battery? What is it's voltage showing?
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #3
Was it a new, rebuilt or reman'ed alternator? What brand was it?
How about the battery? What is it's voltage showing?
New alternator--AC/DELCO
New battery--AC/DELCO---voltage showing between 12.6---14.0. On cold start about 12.6 initially and climbs to 14.0 then
comes down and settles to about 13.6 when idle comes down to normal.
When headlights are on and I brake and/or use a power window voltage comes down and stalls out about 95% of the time.
 

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2011 DTS Premium w/1SD | 1999 Deville Base (RIP @179K Miles)
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404 Posts
Are the battery terminals making good contact? Are the terminals free of corrosion?

Do you ever get a "Battery Not Charging" message?
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #5
Are the battery terminals making good contact? Are the terminals free of corrosion?

Do you ever get a "Battery Not Charging" message?
Terminals real clean and making good contact. "No" battery not charging message at all & no codes.

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Would an intermittently bad alternator produce a code or not?
I know just because it`s new does`nt mean it could a bad one.
I`ve had new parts go bad before.
 

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2011 DTS Premium w/1SD | 1999 Deville Base (RIP @179K Miles)
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404 Posts
Did you install any aftermarket equipment such as a radio?

It could be a bad battery, but maybe something is causing a very high load on the battery and when you press the brakes, the car shuts off.
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #8
What is the static (engine off) battery voltage?
Engine off voltage on cold start is 11.8 and it starts ok.

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Did you install any aftermarket equipment such as a radio?

It could be a bad battery, but maybe something is causing a very high load on the battery and when you press the brakes, the car shuts off.
It`s all stock-- no aftermarket stuff. Had battery checked Friday at my mechanics place and it checked ok.
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #10
That may be your problem.
What does that indicate then--battery or alternator?
Even though it`s in the yellow zone it does charge up to 14.0 then tapers down to 13+ after engine idles down.
All I know at this point is this is a mystery issue. It`s real unusual for my 7 years trusted mechanic to throw in the towel on
anything--he`s real good at electrical issues and this one really has him stumped.
During the past year we`ve thrown 3 new batteries and 2 new alternators at this. He was hoping for some codes to show,
but none do.
He`s hoping a GM dealership has more knowledge on this and he wants to know what the solution is to it. He told me to let
him know what it is if they figure it out.
I`ve reluctantly set an early Monday morning appt. at local GM dealership.
I don`t know whether or not to let them know what`s been done previously or to just show the tech how it stalls out and let them
figure it out.
 

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White Diamond '03 DHS (with DTS floor shift)
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If this is the 3rd battery with the same problem, I doubt it's the battery then.
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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1,673 Posts
Discussion Starter #14
Took it into local GM dealership today and expecting the worse, but it turned out better.
They found an "overheated ground wire connector near battery terminal" so they "replaced butt connector and added an extra ground wire from
engine to body".
I tested it myself before paying and it took all the heaviest electrical loads all at the same time without even flinching!
$102 total.
Time will tell whether it stays good or not.

Thought I`d let you all know and in case someone else ever has this issue.
 

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70 Deville 77 Fleet 78 Seville 92 Deville 03 Deville
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3,310 Posts
Thanks for posting that fix. Was the butt connector a previous repair attempt in the car's history? It doesn't sound like it's supposed to be there.
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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Discussion Starter #16
Thanks for posting that fix. Was the butt connector a previous repair attempt in the car's history? It doesn't sound like it's supposed to be there.
You`re welcome.
I really don`t know if it was a previous repair or not.
Just happy it`s ok for now---hopefully it holds up.
For a long time I never knew if I was going to get to my destinations or not in my '95 and with my '78 Deville in the body shop now
getting complete new paint and body work,I don`t have a backup ride.
Got some peace of mind now.
 

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1991 Cadillac Sedan deVille
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530 Posts
Hi.

Glad I saw this. Are there any updates? Is it still running OK?

I am having a similar problem with my '91 DeVille with the 4.9L. It started about 8 weeks ago. The car always starts fine, etc, but under an "electrical load", when I stop at a red light/stop sign, it started to bog down and splutter like it wants to stall. It starts when just the headlights are on (rough running at times), but when you also have on the HVAC fan on high, it really stumbles and splutters and seems like it may stall. No engine warning lights are on. The alternator was tested at Advance a few weeks ago and he said it was fine, but it was just a kid, so he may not have known what he was talking about, but I would think if it was that bad and was the alternator the charge/battery light would be on?

I took to one of my mechanics to check my engine coolant leak (which they repaired), but said they could not duplicate the problem... naturally. lol. Obviously they didn't let it fully warm up because that is when it does it. I just think they didnt know what it was, so they said it didn't do it, because when I went home after getting it that evening, it did it again to me.

Also my MPG is going way down... I was averaging 19.2 back in September, now I am down to an average of 17.2 and falling. Also, I have not had to let the car set and warm up in the mornings, as it has not really been cold. I am glad I have had my new car to drive until I could get this one checked and have saved a lot of gas, but like driving this car on the freeway, so want to get it fixed. I also want to sell it to get another Cadillac, preferably a Fleetwood.

I will check around the battery cables tomorrow for anything that may look awry. Thanks!
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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Discussion Starter #18
Hi.

Glad I saw this. Are there any updates? Is it still running OK?

I am having a similar problem with my '91 DeVille with the 4.9L. It started about 8 weeks ago. The car always starts fine, etc, but under an "electrical load", when I stop at a red light/stop sign, it started to bog down and splutter like it wants to stall. It starts when just the headlights are on (rough running at times), but when you also have on the HVAC fan on high, it really stumbles and splutters and seems like it may stall. No engine warning lights are on. The alternator was tested at Advance a few weeks ago and he said it was fine, but it was just a kid, so he may not have known what he was talking about, but I would think if it was that bad and was the alternator the charge/battery light would be on?

I took to one of my mechanics to check my engine coolant leak (which they repaired), but said they could not duplicate the problem... naturally. lol. Obviously they didn't let it fully warm up because that is when it does it. I just think they didnt know what it was, so they said it didn't do it, because when I went home after getting it that evening, it did it again to me.

Also my MPG is going way down... I was averaging 19.2 back in September, now I am down to an average of 17.2 and falling. Also, I have not had to let the car set and warm up in the mornings, as it has not really been cold. I am glad I have had my new car to drive until I could get this one checked and have saved a lot of gas, but like driving this car on the freeway, so want to get it fixed. I also want to sell it to get another Cadillac, preferably a Fleetwood.

I will check around the battery cables tomorrow for anything that may look awry. Thanks!
Ever since the fix the GM mechanics did,posted in this thread earlier, it`s been running great---handles all heaviest electrical loads with"out" flinching at all.
 

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1995 SEDAN DEVILLE-4.9 & 1978 SEDAN DEVILLE-425
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Discussion Starter #20
Thanks! Great news! I will definitely check out around the cables, etc tomorrow. Keeping my fingers crossed.
Also remember they added "an extra ground wire from engine to body".
More specifically they connected 1 end of the ground wire to very front on engine and other end to frame--both under the hood. Extra ground wire is about 18" long.
 
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