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· Registered
1992 Seville 4.9
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34 Posts
Discussion Starter · #1 ·
So I’m back here again hoping you guys can help me with my trash pile. 1992 Cadillac Seville. I’ve been slowly rebuilding the car and the more I fix it the more it breaks down. My current problem has me chasing my tail. If I drive the car and have my foot on the gas it’s fine. If I let off the gas to slow down or come to a stop, I can watch the battery voltage drop until the car shuts off and totally dies. Usually have to wait about an hour or more and it will start again and then do the same thing. It’s been sitting for awhile since I haven’t had time to mess with it. I jumped it the other day and it ran in park for a solid hour. So it will run in park but if I try to drive the car it looses power. Battery is the second one I’ve put in within a year, alternator was new a year ago, spark plugs, fuel pressure regulator, fuel pump&filter are all new. Distributor rotor is new and the distributor cap and ignition coil are sitting here in a box gong in soon. This isn’t the typical Seville power draw where it looses power from sitting and needs to be recharged. I can start the car every day no problem but if I turn it back off after it’s been running it won’t start again for at least an hour. But if I leave it running in park it runs fine. Please help! I haven’t the slightest clue what’s going on here and I just wanna take my caddy for a Sunday drive again.
 

· Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
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22,513 Posts
So I’m back here again hoping you guys can help me with my trash pile. 1992 Cadillac Seville. I’ve been slowly rebuilding the car and the more I fix it the more it breaks down. My current problem has me chasing my tail. If I drive the car and have my foot on the gas it’s fine. If I let off the gas to slow down or come to a stop, I can watch the battery voltage drop until the car shuts off and totally dies. Usually have to wait about an hour or more and it will start again and then do the same thing. It’s been sitting for awhile since I haven’t had time to mess with it. I jumped it the other day and it ran in park for a solid hour. So it will run in park but if I try to drive the car it looses power. Battery is the second one I’ve put in within a year, alternator was new a year ago, spark plugs, fuel pressure regulator, fuel pump&filter are all new. Distributor rotor is new and the distributor cap and ignition coil are sitting here in a box gong in soon. This isn’t the typical Seville power draw where it looses power from sitting and needs to be recharged. I can start the car every day no problem but if I turn it back off after it’s been running it won’t start again for at least an hour. But if I leave it running in park it runs fine. Please help! I haven’t the slightest clue what’s going on here and I just wanna take my caddy for a Sunday drive again.
=====================
it COULD BE several different things -
either the alternator is failing -
OR the battery is defective thus sucking ALL of the power the alternator can supply -

I would disconnect the battery - charge it for at least 24 hours - then have it LOAD TESTED -
 

· Registered
1992 Seville 4.9
Joined
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34 Posts
=====================
it COULD BE several different things -
either the alternator is failing -
OR the battery is defective thus sucking ALL of the power the alternator can supply -

I would disconnect the battery - charge it for at least 24 hours - then have it LOAD TESTED -
I’m starting to lean towards the battery being bad. It’s the second one I’ve put in the car in recent months but I did get it from advanced auto and I honestly never bought batteries or really anything from there before since I’ve always heard they have a reputation for selling people bad parts. I have a multimeter but I’m not the brightest crayon in the box and I’m afraid to use it because I don’t want to mess anything else up.

Let's move your post to the correct forum for your car. More likely to get answers there. Welcome back.
I apologize. It’s been awhile since I’ve been back here and I wasn’t sure where to post it. Thank you though. This forum has been a lifesaver for me!
 

· Administrator
2002 F55 STS, 2014 Explorer XLT, F-150
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79,975 Posts
What voltage does the DIC show at Key: ON? Should be 12.4 to 12.6 volts - battery voltage. After START the system voltage (alternator charging and carrying car electrical load) should ramp up to about 14.2 to 14.8 and stay there.

Set the VOM to Volts DC and connect to a positive 12 volt source and a body ground.

A fully charged "12 volt" lead-acid battery should show 12.6 volts when disconnected from anything for a half hour.
 

· Registered
1992 Seville 4.9
Joined
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34 Posts
What voltage does the DIC show at Key: ON? Should be 12.4 to 12.6 volts - battery voltage. After START the system voltage (alternator charging and carrying car electrical load) should ramp up to about 14.2 to 14.8 and stay there.

Set the VOM to Volts DC and connect to a positive 12 volt source and a body ground.

A fully charged "12 volt" lead-acid battery should show 12.6 volts when disconnected from anything for a half hour.
With the key turned but engine not started it sits around 11.7 when the car is on and running it never exceeds 14.2 but when I let off the gas it dips way down until cuts out completely. I’ll check it later when I get home to see what the battery reads while disconnected.

Don't START TO LEAN. Get facts. Follow the instructions Bass and Sub gave you before you throw parts at it.
Kinda hard not to lean towards things when I’ve been throwing parts at it for 2 years and literally NOTHING works. I’ve been given very solid advice in this forum. But this car is an absolute pile of trash and no amount of facts ever seems to solve my issue. So I’m to the point where I have no other choice but to throw parts into it and hope that one of them works and solves my issue.

What voltage does the DIC show at Key: ON? Should be 12.4 to 12.6 volts - battery voltage. After START the system voltage (alternator charging and carrying car electrical load) should ramp up to about 14.2 to 14.8 and stay there.

Set the VOM to Volts DC and connect to a positive 12 volt source and a body ground.

A fully charged "12 volt" lead-acid battery should show 12.6 volts when disconnected from anything for a half hour.
I took the battery out of my truck and put it in the car and it started right up no issue. Even stayed running when I disconnected the battery so I don’t think the alternator is the issue. Not to mention the alternator was replaced almost exactly a year ago. Put the old car battery back in and it ran until i turned it off. Then wouldn’t start again. I’m starting to think the battery has a bad cell and I just have extremely bad luck since it’s the second battery in a row that’s been bad if that is the case. I might take the battery from my truck and try to drive the car around the block and see if it has the typical power drain issue that I’ve been having.
 

· Administrator
2002 F55 STS, 2014 Explorer XLT, F-150
Joined
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79,975 Posts
NEVER disconnect the battery with the engine (alternator) running - the risk of severe electrical system damage is almost 99.989%. It's a wonder that, when the voltage regulator saw 0 load, it didn't spectacularly self-destruct.

If the battery has a dead (shorted) cell it will go practically dead overnight.

Anything below 12 volts is essentially dead. Some plate voltage, no amp power left.

Rectangle Font Parallel Number Symmetry
 

· Super Moderator
2010 DTS
Joined
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89,562 Posts
Put the old car battery back in and it ran until i turned it off. Then wouldn’t start again. I’m starting to think the battery has a bad cell
If it has a dead cell, I don't think it would have started the first time, but to test it, set your DVM to 20v. Put the red probe on the positive terminal and the black probe on the negative terminal. Have someone try t o start the engine. If you have a dead cell, the voltage should drop to around 9v. This is a "load test".
 

· Registered
1992 Seville 4.9
Joined
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34 Posts
If it has a dead cell, I don't think it would have started the first time, but to test it, set your DVM to 20v. Put the red probe on the positive terminal and the black probe on the negative terminal. Have someone try t o start the engine. If you have a dead cell, the voltage should drop to around 9v. This is a "load test".
I’ll give that a try tomorrow. I appreciate you man. Idk if you remember me or not but you’ve helped me probably at least a dozen times with issues I’ve had with this car lol

NEVER disconnect the battery with the engine (alternator) running - the risk of severe electrical system damage is almost 99.989%. It's a wonder that, when the voltage regulator saw 0 load, it didn't spectacularly self-destruct.

If the battery has a dead (shorted) cell it will go practically dead overnight.

Anything below 12 volts is essentially dead. Some plate voltage, no amp power left.

View attachment 610743
The battery is probably dead due to sitting in extreme cold weather. I hadn’t started the car for a couple of months prior to the other day since it had started dying on me I just parked it and stopped driving it. But I would go out once a week, start it and let it run for 20min then turn it off. Just was afraid to drive it because it would stall out and lose all power every time. I went out of state for a couple of months so it hadn’t been started during that time. I’m going to get a new battery for it but I still feel there’s something else going on that I can’t track down. I am by no means a mechanic in any way. I didn’t think the battery should be taken out while it was running but my ******* neighbor insisted it would be fine and at the time I was out of options and simply hoping he has more mechanical knowledge than me. He apparently does not lol

NEVER disconnect the battery with the engine (alternator) running - the risk of severe electrical system damage is almost 99.989%. It's a wonder that, when the voltage regulator saw 0 load, it didn't spectacularly self-destruct.

If the battery has a dead (shorted) cell it will go practically dead overnight.

Anything below 12 volts is essentially dead. Some plate voltage, no amp power left.

View attachment 610743
You have also helped me numerous times with this car along with Ranger and I just can’t express how grateful I am for you guys and this forum. You’ve been life savers on this project. Seriously.
 

· Administrator
2002 F55 STS, 2014 Explorer XLT, F-150
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79,975 Posts
Thanks for the vote of confidence - but please understand that some of us are here to pass on knowledge gained from many years of wrenching - in my case, since about 1953 or so. Preaching hearsay, rumor, innuendo, ideology is nonproductive - actual fact and experience is the basis of true knowledge.
 

· Registered
1992 Seville 4.9
Joined
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34 Posts
Discussion Starter · #12 ·
So after all this time I finally have things sorted. There was corrosion on some fuses and relays and on some wiring running to and from it. Along with the car starving for air. It needs an idle control valve, a power steering pump and pulley, and I ran some seafoam through it after cleaning the corrosion and she finally starts and runs again. It occasionally stalls but I believe that’s due to the idle air control valve failing which will be replaced this week. I appreciate all the help from everyone.
 
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