View Full Version : Battery light goes on and off?

11-04-2008, 10:16 PM
I have a 1997 Saturn SL with 171,500 miles. Today the battery light went on after restarting the car at the gas station. The head lights were not as bright as I drove the car 2 miles to home. I checked the battery terminals ( took them off and cleaned them) and the serpentine belt for tension. After pressing down on the accelerator a few times the battery light goes off and stays off even when the engine returns to an idle. It now seems that the battery light goes on after the car has been driven for awhile and then restarted. Again, pressing on the accelerator will eventually cause the battery light to go off. Can an alternator work intermittently like this or is the voltage regulator part of the alternator and that part be the cause of this scenario? This is the original alternator. Any suggestions would be appreciated. Thanks.

11-04-2008, 10:22 PM
did you also check the connection at the alt?

11-04-2008, 10:25 PM
Hey there-

I have a 96 Saturn Sl2 with 186k on it. I have the EXACT same problem. It happens in the summer but more in the winter. I have a new battery & alternator because last year the car decided to not start for 10 days. The dealer said usually its the ECM that creates that problem. Sometimes even pushing on the gas a little hard and driving 3 miles doesnt work, but if I turn the car off and back on everything is perfect again. Saturns have a lot of little odd issues. Oh, we also checked all of the voltage at the battery and the alternator and everything is perfect, so I have no clue whats going on.

11-04-2008, 10:46 PM
Check the ground connections going to the block and the ground on the PCM.

11-04-2008, 11:01 PM
I might just end up buying a new engine and putting it in. The coolant keeps disappearing even after I replaced the radiator and water pump. I ran the car for 3 hours thinking it would leak somewhere but it doesn't. I'd rather just get an engine than have car payments.

11-04-2008, 11:03 PM
I did not check the connection at the alternator. That connection is a little harder to get to it would seem.

11-04-2008, 11:04 PM
Check the radiator cap. If it is bad the excess radiator fluid is routed to the intake manifold and get burned up.

11-04-2008, 11:08 PM
I have a 1997 Saturn SL with 171,500 miles. This is the original alternator..

Your running the alternator on borrowed time as its a matter of time before the battery dies and needs replacement along with the old alternator. The light is indicating something wrong with the electrical system. A simple test at your favorite auto store capable of checking the battery/alternator system will reveal what's wrong or you can perform some simple measurements of battery voltage to determine the issues - the alternator is due for replacement and possibly the battery if it was allowed to operate with the battery light going on and off for a long time otherwise the alternator is on its last legs unless you can find loose connections on the alternator.

Usually alternators wear out; the brushes wear down after so many thousands of miles where they begin to lose physical contact and intermittently turn on the low voltage indicator warning you of electrical power problems. Measuring at the battery terminals should show battery voltage around 12.5v+, engine idling 13.5v+, above idling 14.3v+. If the last two voltages don't vary above battery voltage then the alternator is faulty. Remove it for testing before replacement. With so many miles on it, its due for replacement.

11-04-2008, 11:18 PM
I wouldn't say it's definitely the alternator. I have a new heavy duty battery and alternator and all of the voltage is correct, and my battery light turns on and my blow motor/headlights everything is very weak until I either press on the gas hard or turn the car off and back on. It's been doing that for 2 years.

11-04-2008, 11:58 PM
True as dimming headlights still means a voltage drop somewhere and I did leave out the possibility of a worn belt tensioner allowing a loose belt to slip to mimic the same problems as a worn out alternator. Simply pressing down on the belt between the pulleys with a large deflection would mean a worn tensioner and/or stretched belt.

11-05-2008, 06:53 AM
I have a 95 SL-1 with 98k on the clock and had the same symtoms, batt light coming on and off. It ran for about 3 months that way until my wife called one day and was stuck (in the rain of course).

Anyway it was the alternator so we replaced it along with the battery which was orginal. We have had no problems since.

11-05-2008, 07:27 AM
i say alternator also. but before replacing it, find ALL the grounds and clean them thoroughly. also it may be wise to replace the battery cables, especially the positive cable.

11-05-2008, 08:11 AM
You might have a blown diode in your alternator. The alternator works over a couple of phases. However, you are not getting full power from the alternator. By speeding up the engine you are going over those phases that are still working faster.

I've seen this in an old Mercury I used to own.

11-05-2008, 08:33 AM
I am having the exact same thing on my 2004 vue. I have had numerous tests done to the vehicle, including removing the battery completely and allowing it to run. The vehicles engine will not stop when there is no battery, however the battery light comes on showing that the alternator is at least charging and that it detects the battery is gone.

Per the local parts house and mechanic the alternator that I have is good. I have also had the check engine light come on numerous times related to a "Emissions Control Module" Failure. This issue happened at 5k and it was brought to dealer and I was told to ignore it. 10k brought to dealer, same thing nothing that they can do. 17k brought to different dealer, sorry nothing they can do, It seems to happen every 5 to 7 thousand miles. I have ran my vue with this issue for over 3 years as well as with the battery light issue and have not had any issues other than the lights dimming and idling being rough. Rpm's jump due to draw on the system. I am beginning to think that it has something to do with the AC system as when that is off it does not happen.

As of now, I am not ever planning on buying another saturn due to the issues with their service department. They have even told me that the recall for the suspension system is not anything to worry about if I do not drive the vehicle around sharp curves.

11-05-2008, 08:39 AM
I drove to work this morning (35miles) with the battery light off and the headlights bright. When I parked the car I turned the motor off and then quickly restarted the motor. The battery light stayed on and the headlights were dim. It seems like the problem is related to restarting a warm motor. When the motor cools down, the battery light is off and stays off until you restart the motor. Tomorrow I will crawl under the car to clean the alternator conections. Could the voltage regulator be heat sensitive with age? My Haynes manual states that the alternator has an internal voltage regulator. Thanks everyone for your help. This is a great place for getting help.

11-05-2008, 09:10 AM
I vote for Alternator as well. If the Serp Belt is original or has over 30K miles on it...you may think about replacing the Serp Belt.

Belt Tensioners can vary the speed of the belt too, meaning that by pressing down on the gas, you are running the belt at a higher speed to compensate for the Alternator not working properly.

When you get underneath your car, check your connections. There will be a Plastic Tab Electrical Connection, and a "Fusible Link" that is a 10MM bolt head on the Alternator that runs from the Alternator to the Starter, where it is attached to the Starter with a 13MM Bolt. Check both of these connections; make sure they are clean.

It is very possible too that the Fusible Link may be "Melted" onto the 10MM bolt on the Alternator.

I just replaced the Delco-Remy Alternator in my 94 SL2. I believe it was the original Alternator. I bought a New Alternator for $134.99 at Autozone ($154 after taxes, etc.)...took my old alternator back for the $10.00 Core return; and the car runs great. I had a battery light on in my car as well, but the Battery in there was only a 6 months to a year old; Autozone tested the battery; came back good. Replacing the Alternator solved the problem.

Does your car start okay when it's cold? You may have a Starter issue as well, if the alternator checks out okay.

As FDryer mentioned, you should have 12 V of power when the car is sitting and not running. When you start the car, you should have anywhere from 13-15V of power coming from the Alternator. Anything less than 13V when the car is running under load (Lights, and Heater running) means that you should replace the Alternator, as the Alternator is struggling to keep up with the rest of the car power-wise..

Replacing the Alternator is relatively simple, if you are tool savvy. Remove the lower part of the splash shield in the wheel well, jack up car, remove passenger wheel. Remove Serp Belt. It's held in by (2) 13 MM Bolts, one; you access through the top of the engine bay underneath the PS Pump, the other from underneath the car...the bottom bolt is a 13MM bolt that is about 3 inches in length. You have to use a box wrench on one end and a Socket on the other end. Undo the plastic tab electric connection, take off the splash shield (10MM Bolt), Rubber boot for the fusible link, 10MM bolt for Fusible link, remove alternator thru the wheel well. Careful, as the Alternator is a bit heavy, esp. while lying on your back on a creeper. Installing is the reverse of removal.

Check the How-To Section...there is probably an illustrated version of the above.

11-05-2008, 10:00 AM
My starter works well, however the starter is also original. The car does have over 171,000 miles. Thanks for your help. I will remove and clean the connections going to the alternator tomorrow. If that doesn't work- its time to buy a remanufactured alternator before I am left stranded on the road with a dead battery.

11-05-2008, 10:25 AM
... Tomorrow I will crawl under the car to clean the alternator conections. Could the voltage regulator be heat sensitive with age? My Haynes manual states that the alternator has an internal voltage regulator. Thanks everyone for your help. This is a great place for getting help.

Almost all alternators have built-in voltage regulators as opposed to Ford (for example) and some of their models using an external voltage regulator. Every voltage regulator is solid-state and temperature stabilized to accurately control the alternator as a simple plug n' play automotive part. Alternators supply all of the car's electrical demands and charges the battery simultaneously as you'll read of many people pulling a battery cable off while the engine's running to demonstrate a test (that's not recommended) of the ability of the alternator to run the car. There is virtually no worry about temperature instability affecting any alternator in a normally operated motor vehicle as the regulator automatically senses voltage/current variations and adjusts accordingly to maintain approximately 14.3v (approx.) all the time. Every alternator built will normally operate until the wear related parts wear down, requiring either rebuilding or replacement. The electronics are so reliable that failures are becoming rare. Failures are either mechanical or electrical and the electrical failures can be determined between incorrect wiring or worn components.

11-05-2008, 06:46 PM
Ok again...this morning I turned on my car and noticed the battery light was on and the lights were dim...and the blower motor was barely blowing.....I thought "whatever" so I put the car in reverse and it clunked. I then put it in drive once I got onto the street and the trans clunked again...I pressed on the gas and the car would barrreeellly move....like the entire electrical system was messed up and not even the tranny would work.....so I put the car back in the driveway and took the gas hogging truck to work.

Anyways I come home tonight...turned the car on...runs perfect...like nothing ever happened. This has happened to me a few times now. I have a new alternator and new battery and belt.

11-05-2008, 07:04 PM
There is a big red wire that runs from the battery to the UHJB (fuse box), try cleaning this connection. There is a little cover to take off and then you can unbolt it and clean the connection.

11-06-2008, 11:28 PM
Crawled under the car and checked the electrical connections at the alternator and they were not corroded. So I installed a remanufactured alternator from Advanced Auto Parts ($110.00) and so far the battery light has stayed off. I also checked the voltage of the battery with the motor running. The new alternator checks out okay. Thanks for the help- I also want to thank Richpin for the excellent video on removing the alternator.