gth

I have a 2000 silverado ext 4x4 5.3l that I have been having a little
problem with.
A few days ago I was driving and noticed the battery light come on and
the volts gauge was reading around 10 -11volts. I turned off all
accessories and headed her for home.
Once home I took the battery (delco factory) to Canadian tire for them
to test it. It tested "replace". So I did with a new 875cca terminator
battery. When I installed the new battery the truck started fine but I
noticed the battery warning light was still on. I let it run for 20min
or so to see if it would charge. (or what ever was wrong might
magically fix itself) The light didnt go out so I tried some of the
accessories to put a load on it. The wipers and blower motor ran but
noticeably slowly.
I just decided to let the truck run with all accessories off. The
battery light didn't go out so after running for 1/2 hour or so I shut
off the truck and the the battery now shows 11.7V across the terminals.
I charged the battery back up to show 12.6V across the terminals.
Then I started the truck and checked the voltage across the terminals
with the truck running (no access on at all)......11.3V....What
the.....and the bleeping battery warning light is still on.
I tried revving the truck to 2000-2200 rpm (no access on at all) and
the voltage across the battery went up to 11.49 at one point but it
also fluctuated down to 11.27 also....
Does this sound like a new alternater to go along with my new
battery???? What are the odd that both the battery and alternator would
crap on the same day???
PS. I have never had another issue with this truck until this.

48fan

It is very possible that your Alternator going bad was what caused your battery to go bad. If your Alternator does not charge your battery correctly then your battery will start to sulfate and the surface area ofthe lead plates will be reduced causeing your battery to not hold a charge.
With your truck running, check to see what your Alternator output is.

gth

I checked it by plptting the + wire from my multimeter on the Positive wire coming out the back of the alternator and the - wire from my multimeter on the neg terminal of the battery and got 11.47V....

I also checked from the pos wire in back of the starter to a remote grounded object and got 11.47V


Thnaks for the help...

48fan

I just reread your post and you said that you read 11.3V accross the batt terminals; you should have read 13.8V to 15.3V with the vehicle running. Your alternator is either toast or the connectionsto your alternator are bad.

golfer

It's your charging system.
Afaulty battery can destroy an alternator and a faulty alternator can destroy a battery.

vinton

When I start the engine it seems to be fine before I turn on the lights , that will drop all power so it will kill the engine.. can this be the regu

Doug D

It could be the regulator, but the first step I would take is clean the battery posts and connecting cables and have the battery and charging system checked. If you have a multi-meter a fully charged battery should show 12.6 volts with the engine off and 13.8-14.4 volts with the engine running. It's rare for a regulator (most are in the PCM or ECM) to go bad. It may be just corrosion on the battery posts and connecting cables. Remove the cables from the battery posts and clean the posts and connecting cables with a wire brush. Even if they "look" okay a film can build up and reduce the current trying to go through. After cleaning the posts and cable connections reconnect and check the voltage.

Jakes Belliri

Battery light on.. I have a big mystery ......A . Mystery no one can solve ..I brought the truck to two mechanics..neither were able to figure out what's wrong or why the battery light comes on and stays on ...... I have a 2005 Chevy Tahoe z71. 5.3. A while back I made a huge mistake by crossing the cables on the battery. I tried to put the positive on the negative and vise versa. It began smoking from the red box that connects the two big cables from battery and alternator. Anyway. That info probably wasn't necessary and hopefully it didn't confuse the situation ........... . Bottom line is........ Battery light comes on about one minute after starting the vehicle..........I bought a brand new battery........a brand new alternator....... A a generator battery control module....... The battery charges........... I've sat with the vehicle running for half hour with all electrical components on to see if there was any drain. Wipers, lights, radio, AC, etc etc. The voltage guage on the dash board stays at 14 volts. But the light goes on and stays on. I attempted to replace the PCM unit but the company I bought it from is a worthless under handed rip off............. ( Stay away from FLAGSHIP ONE ). OUT OF NEW YORK. THEY WILL TAKE YOUR MONEY AND NOTHING CAN BE DONE LEGALLY ABOUT IT. IVE TRIED. ................. my light is on and both mechanics are telling me just deal with it. It's not going to matter. As long as it's working. Which is fine. I want to re register it and put it back on the road. And having a battery light on won't cause me to fail inspection....... But I just don't want any unsuspecting issue to occur if driving it and something else happens and I get stuck and end up in a jam. Does anyone know what the issue is ,? And if so. .can you explain it and try to make it simple because when it comes to electrical. I have no clue. I'd appreciate any help. Seriously. I've already put 2000 into this truck in parts alone. And all of those parts were from manufacturers. Not retail stores. .so yes. I put in a lot of parts. I just don't know what else to do to fix this.

mountainmanjoe

When you reverse the polarity, you can fry pretty much every control module. PCM, BCM etc.....

EricStrong

Yes, these are symptoms when your alternator doesn't charge a battery. Check the voltage on the alternator's connectors to exclude cables problem and then go to an automotive service to repair.