Question about 1999 Cadillac Seville

1 Answer

Overcharging Alternator I have a 1999 Cadillac STS with an alternator I replaced. The alternator is a 140 amp and after being replaced, started the car right up. But now instead of my car NOT charging the battery, its charged all the way up to as high as 16.4 volts when idling. If I turn all the accessories on it still hovers around high 15v and low 16v causing my stovk stereo to clip and windows not to work. If the engine is off with the key in the ignigtion, the car will read at 12v. (keep in mind I tested the voltage with a meter as well as what the car said, and my battery is the same one that never drained past 11.8v with the previous alternator)

Posted by on

Ad

1 Answer

  • Level 3:

    An expert who has achieved level 3 by getting 1000 points

    All-Star:

    An expert that got 10 achievements.

    MVP:

    An expert that got 5 achievements.

    President:

    An expert whose answer got voted for 500 times.

  • Cadillac Master
  • 3,433 Answers

Very short lesson on the charging system. Remember this, The higher the voltage the less the amps.in turn low voltage, high amps. When the Alternator is charging at or above 15v, It is virtually pure voltage and as a charging device is cooking your battery, not charging it. The alternator, though defective, is safe and your battery is in harms way. When an alt. is charging at or below13 volts, The charging amperage is approaching max output of the alternater, which, if maintained at that rate will overheat and cause alt, failure, The proper charging range is 13.6 to 14.2. Each end is the limit just short of maximum and eminent failure. Example: charging at 12v means the alternarer is at max output and is in danger of sling solder, litteraly. When you smell dulphur coming from the battery, The alt. is running wide open on the voltage and your batt ison death row. So, back to your problem. One more thing. All accessories that are designed to operate on 12v are art risk of being damaged from excess voltage. Some have a voltage limiter to protect against surges but not all. Oh, That is one heck of a hot alt at 140 amps. Is that original equipment? Well, I know I may have rambled a bit but I hope it helped you understand how it works so you can come to the conclusion I have. The Alternator has a bad regulator and is in whole or part defective. Good Luck, Ned

Posted on Nov 12, 2009

Ad

1 Suggested Answer

6ya6ya
  • 2 Answers

SOURCE: I have freestanding Series 8 dishwasher. Lately during the filling cycle water hammer is occurring. How can this be resolved

Hi,
a 6ya expert can help you resolve that issue over the phone in a minute or two.
best thing about this new service is that you are never placed on hold and get to talk to real repairmen in the US.
the service is completely free and covers almost anything you can think of (from cars to computers, handyman, and even drones).
click here to download the app (for users in the US for now) and get all the help you need.
goodluck!

Posted on Jan 02, 2017

Ad

Add Your Answer

Uploading: 0%

my-video-file.mp4

Complete. Click "Add" to insert your video. Add

×

Loading...
Loading...

Related Questions:

2 Answers

My car is overcharging what could it be to caves it to overcharged,i am a disable veteran,need help?


Sounds like a faulty regulator rectifier on the alternator borrow a compatible alternator to test the charging system
It usually is cheaper to replace the whole alternator than have them repaired

Mar 24, 2016 | 2002 Cadillac Deville

1 Answer

Two batteries two alternator and still says service charging system battery not charging and as soon as battery is drained won't start Cadillac 1998 sts


Could be a wiring problem.
Have you checked the wire from the alternator to the battery or starter, and is the alternator being entergized by the key switch ?

Mar 21, 2016 | Cadillac Cars & Trucks

1 Answer

Firing order for 2005 cadillac sts 3.6liter v-6


The drivers side is cylinders 1,3&5 the last cylinder closest to the firewall is five unless it is front wheel drive then the front of the engine where the alternator is located will be the head on the right from the alternator count the third sparkplug that's number five!

Jan 16, 2015 | 2005 Cadillac STS 3.6

1 Answer

How do I replace the alternator in my 2005 Cadillac sts


Unbolt it, remove it and then repeat in reverse with new alternator. No Just go buy a Chilton or haynes manual when you buy the alternator

Oct 28, 2014 | 2005 Cadillac STS

1 Answer

I have a 1994 cadillac sedan deville with a 4.9 engine. The message center in the instrument cluster says the voltage is too high. I have replaced the alternator but still comes on . Maybe you can help me....


The first thing to do is have the battery tested and then the charging system checked, this will show you if its overcharging,if it is overcharging then take a look at the wiring going to alternator,and also a bad battery can also cause a problem so first find out if message center is displaying the correct message, this will show if center is okay then move on to battery testing then alternator test, there may be a problem with the wiring or a defective alternator.

Aug 07, 2010 | Cadillac DeVille Cars & Trucks

5 Answers

Cadillac STS 1999 electric problem


With that voltage I would be looking for possible short in wire harness or defective relays

Mar 17, 2017 | 1999 Cadillac Seville

1 Answer

Why is the battery draining on my 2001 cadillac sts. Checked fuses. What is the losd


It may be that your alternator isnt charging your battery. have your alternator checked. Also could be that you have dead cells in the battery and battery wont hold a charge. have battery checked also.

Aug 25, 2009 | 2001 Cadillac Sts

1 Answer

1997 CADILLAC STS


fusable link between the alternator and the starter sounds like the problem ..if link is blown the alternator will not send the charge to the battery or the motor cr is running ofth battery right now ... if this is helpful please rae

Apr 19, 2009 | Cadillac STS Cars & Trucks

Not finding what you are looking for?
1999 Cadillac Seville Logo

705 people viewed this question

Ask a Question

Usually answered in minutes!

Top Cadillac Experts

yadayada
yadayada

Level 3 Expert

76070 Answers

Colin Stickland
Colin Stickland

Level 3 Expert

22156 Answers

Jeff Turcotte
Jeff Turcotte

Level 3 Expert

8266 Answers

Are you a Cadillac Expert? Answer questions, earn points and help others

Answer questions

Manuals & User Guides

Loading...