Battery light on?

Tiny
STINGMD
  • MEMBER
  • 2007 CHEVROLET SILVERADO
  • 0.8L
  • V8
  • 4WD
  • AUTOMATIC
  • 70,000 MILES
I have a battery light on I was wondering what I should do?
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Monday, November 2nd, 2015 AT 11:13 AM

26 Replies

Tiny
WRENCHTECH
  • MEMBER
Hello,

It sounds like you have an alternator that needs to be replaced but to be sure here is a guide to confirm the issue with a guide to help walk you through the alternator replacement if needed

https://www.2carpros.com/articles/how-to-check-a-car-alternator

and

https://www.2carpros.com/articles/how-to-replace-an-alternator

Please run down these guides and diagrams and report back.
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Monday, November 2nd, 2015 AT 12:19 PM
Tiny
RKAUSTIN
  • MEMBER
Thank you for this post I had this problem and had to get a alternator cost me $102.00 for an AC Delco Unit. I love this site.
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Saturday, August 17th, 2019 AT 1:47 PM
Tiny
PANDA71
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • V8
  • 2WD
  • AUTOMATIC
  • 27,000 MILES
My battery light stays on what could it be. Truck runs fine no other problems
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Saturday, August 17th, 2019 AT 1:47 PM (Merged)
Tiny
BLUELIGHTNIN6
  • EXPERT
The battery light usually indicates a problem with the charging system. You need to have your battery and alternator tested. Most auto part stores such as AutoZone or Advance Auto Parts will test them for free, on or off of the vehicle.

If both test good then check the battery terminals and cables for corrosion and ensure they are tightened properly.

This guide can help

https://www.2carpros.com/articles/everything-goes-dead-when-engine-is-cranked

Thanks for using 2carpros.com!
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Saturday, August 17th, 2019 AT 1:47 PM (Merged)
Tiny
2CARPROS-ARCHIVES
  • MEMBER
  • 2005 CHEVROLET SILVERADO
  • 111,736 MILES
For the past year my red battery light comes on sometimes when I drive.
Mostly during the daytime. When I stop a restart the motor it goes out sometime the rest or the day and sometime get come back on in a few miles. I have had the alternator check several times by serval people and they say its OK. It's only gone dead one time and that was in the beginning about a year or so ago I need help

Ray
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Saturday, August 17th, 2019 AT 1:48 PM (Merged)
Tiny
CARADIODOC
  • EXPERT
The charging system has to be tested while the light is on and the problem is occurring, otherwise, of course it will test okay. GM has WAY more trouble with their generators than anyone else, but intermittent problems are not common. Usually they just fail. When they do, to prevent a lot of repeat problems, replace the battery at the same time unless it is less than about two years old.
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Saturday, August 17th, 2019 AT 1:48 PM (Merged)
Tiny
MISFITSKID
  • MEMBER
  • 2003 CHEVROLET SILVERADO
  • 97,000 MILES
Had the alternator and the battery checked and they are OK. The orginal battery died so a battery charger was placed on the battery. Now the battery light will come on the engine will stall if the motor goes below 500 RPM at an idle.
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Saturday, August 17th, 2019 AT 1:48 PM (Merged)
Tiny
WRENCHTECH
  • MEMBER
First eliminate all vacuum or air leaks in the system. You may have a bad IAC ( idle air control) but try cleaning the throttle body first. Remove the intake snorkel, have someone hold the throttle wide open for you and scrub the back side of the throttle plate and surrounding bore with an old tooth brush and some carb cleaner. Be sure to spray some into the small holes next to the throttle plate. That should help stabilize the idle. If it still has a problem, replace the IAC.
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Saturday, August 17th, 2019 AT 1:48 PM (Merged)
Tiny
DSTAM932
  • MEMBER
  • 2004 CHEVROLET SILVERADO
  • 6.6L
  • V8
  • TURBO
  • 4WD
  • AUTOMATIC
  • 268,000 MILES
Install new alternator working great and charging, but the battery light will not go off, tried to locate alternator
fuse no luck. Found battery fuse under the hood in the fuse box, fuse is good, Don't where else to look.
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Saturday, August 17th, 2019 AT 1:48 PM (Merged)
Tiny
JDL
  • EXPERT
Did you check for applicable trouble codes? Some of the national brand autostores will check codes for free. Check manufacturer specific codes as well as po codes.

Our database says to use a scanner that will show live engine data for your vehicle, check ipc, instrument panel cluster pids, if the charging system reading is correct and the lamp is on, replace the ipc. I won't replace anything unless diagnostics point me in that direction.
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Saturday, August 17th, 2019 AT 1:48 PM (Merged)
Tiny
DSTAM932
  • MEMBER
I have a Edge programmer the code was PO621 Generator L
Terminal Circuit, Generator not charging, placed Volt meter on battery
with engine running, shows 14 amps also the volt gauge in truck also shows 14 amps. Could I disconnect both battery cables wait 10 minutes
and let the computer reset?

Dale
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Saturday, August 17th, 2019 AT 1:48 PM (Merged)
Tiny
MIKE0555
  • MEMBER
  • 2002 CHEVROLET SILVERADO
Electrical problem
2002 Chevy Silverado V8 Four Wheel Drive Manual

battery light is flashing, battery is charging, alternator putting out 13-14 volts, battery 12 volts wihen not running
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Saturday, August 17th, 2019 AT 1:48 PM (Merged)
Tiny
RASMATAZ
  • MEMBER
Get the computer controlled of the alternator field generation duty cycle signal circuit checked out and also check battery and alternator connections-
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Saturday, August 17th, 2019 AT 1:49 PM (Merged)
Tiny
RWLUFKIN
  • MEMBER
  • 2006 CHEVROLET SILVERADO
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 180,000 MILES
My Alternator went out while on my way to work. The Battery light come on solid as it should have. But after my mechanic replaced the defective Alternator now the Battery light flashes on and off while driving and then goes solid. I had the Battery replaced and the Battery light still flashes and then goes solid. The voltage is 14.1. No fault codes. Any solutions to this problem. Thanks, Robert W.
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Saturday, August 17th, 2019 AT 1:49 PM (Merged)
Tiny
MERLIN2021
  • EXPERT
My thought is either corrosion on the battery cables, especially the negative, check for voltage drop on the both cables. Shut off the truck. Measure battery voltage, then measure the negative cable at the block and + battery post, if not the same as battery voltage replace the cable, do the same on positive cable but touch _ post, readings should be battery voltage. If OK re check connection to alternator, and check small ground spur wire to the fender if you have one. Also when you say no codes, did you scan it with a tool capable of reading B and U codes? Or with a generic tool for P codes? B and U codes cant be read with generic tools and do not set the service engine light. This truck has a generator battery control module that monitors the charging system. And the first step is ALWAYS to scan.
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Saturday, August 17th, 2019 AT 1:49 PM (Merged)
Tiny
RWSCHLAF
  • MEMBER
  • 2002 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 70,000 MILES
The message center flashes a battery picture 2-3 times and then goes out. This happens about every 10 minutes while driving. Battery was replaced and the voltage after setting over night is 12.3-12.4. After start voltage goes up to about 14.4-14.6. Battery terminals are clean and I cleaned the large wire at the back of the alternator. Driving and starting all seem fine.

Thanks for the info. I don't have a scan tool but have ordered one. I also cleaned the connections at the red junction box and reseated the small 4 conductor connector on the alternator. I looked clean. I am monitoring the voltage wit a DVM plugged into the cigarette lighter and after the cleaning, it is working better. I noticed that when the light was blinking (after 2 hours of operation), the voltage dropped to 14.1. I happened to change from Auto 4WD to 2WD and the light went out and voltage came up. It has been working fine after. I will get the codes and let you know. Thanks for the help.

The final update is that all has been working fine for the last several days and no Battery light, voltages are fine and the truck operates fine. I did check for fault codes and none were found. Must have been coincidental with the problem clearing when I changed the 4WD controls. Thanks for your help.
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Saturday, August 17th, 2019 AT 1:49 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
It sounds like everything is good and working as it should. To diagnose this problem, you will need to drive the vehicle with an on board scanner that will identify why the light is coming on. It could be a faulty regulator.

Let me know if you have other questions.

Joe
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Saturday, August 17th, 2019 AT 1:49 PM (Merged)
Tiny
MYSOFTAIL98
  • MEMBER
  • 2002 CHEVROLET SILVERADO
  • V8
  • 4WD
  • AUTOMATIC
  • 91,000 MILES
I have a 2002 Silverado Z71 5.3L with 91K miles. My battery light comes on for a few seconds and then off again while driving. Also sometimes the votage jumps back and forth from 14.6 to 13.4 at idle. I have replaced the alternator with a new delco 130 amp. I also change the belt at the same time. The battery is about 7 months old and I have tested it just to make sure its good. Lastly I had a new PCM installed from the dealer. Where should I look next? Thanks for any help.
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Saturday, August 17th, 2019 AT 1:49 PM (Merged)
Tiny
ZACKMAN
  • MEMBER
Check your belt tensioner. Over time, the spring in the tensioner assembly gets weak/damaged and the belt gets loose and not properly tensioned. This will cause the light to turn on.

You may also wish to bring the vehicle to a parts store and have them check the entire electrical system, not just battery, but starter and alternator.
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Saturday, August 17th, 2019 AT 1:49 PM (Merged)
Tiny
ZACKMAN
  • MEMBER
While I understand that you have replaced the alternator, you should check the entire system to make sure that the ENTIRE system is working properly. The diagnostic is meant for use with GM scan tool, but you can do some of them yourself. Start by checking if the new alternator is working properly. You may have an intermittent problem, that can be a result of poor connection from the alternator and the PCM. The best way to check the entire system is to bring the vehicle to an auto parts store and have them test the entire electrical system. If the test comes back good, and you still have the intermittent problem, you have poor/damage connection.
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Saturday, August 17th, 2019 AT 1:49 PM (Merged)

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