Regardless of the expense..
Batterys arent designed to last 5 yrs..it probably has whats commonly called a "dead charge". It reads fully charged but it isnt. (Its dead)...
My money is on a new battery.
Good Luck and keep us posted when its running again.

 

This is some kind of computer issue, body control module most likely. Since the check engine light comes on, both the PCM and instrument panel are working and talking, but the body control module should be telling the instrument panel to run a lamp test, and that doesn't happen.

Also possible it's the ignition switch, but since the check engine light comes on, I don't think that's likely.

 

Took battery to autozone. They said it was fine, as I expected. Spent a solid 5 hours going over my connections cleaning them. Still nothing.

BCM was replaced with a brand new module and reprogrammed in mid 2012.


There's some kind of noise going on when I turn the car from ON or ACC to off. Might need some headphones to hear it better. Maybe someone can tell me what this noise is? I tried to get into the general area of where it was coming from.

 

When I touch my negative lead to this ground and the positive lead to the battery I'm getting a reading of exactly 2.58volts. Shouldn't it read around 12.4?

 

I have one of these grounds going directly to the battery, and the other going to the body.


Touching my lead here and the other on the battery I'm getting 2.58v


Also, even though my battery charger is saying my battery is near full it's reading 12.3. Shouldn't it read a bit higher if it's near full?

I'm going to let it charger over night at 2amps and see what it does tomorrow.

 

Ok one last post before I get to bed. Sorry for all the posts I'm just tossing around ideas in my head. Trying to not rule out the simple things, like the battery.

I'm thinking I may have a bad battery. Here's why. My car was broke down about a month ago (I've been having all kinds of great luck lately, luckily it just needed a tuneup) so it was sitting in my driveway for for a few weeks and the battery eventually drained during this time. After a few weeks I noticed a.... I guess it would be a clicking noise coming through the car alarm speaker (it was doing this Monday right after the car died along with the clicking from the right fuse box area which was in sync with the noise coming through the speaker). Tried to unlock the car and nothing. Used the key, tried to start and it wouldn't. I can't remember if it tried to crank or if it did absolutely nothing. Anyway interior lights and everything were out like it is now. Ended up jumping it with my moms car and charged it that night.

Monday when I was trying to start it there was some clicking going on, now there's nothing. Maybe the battery had a little bit of juice and now is completely drained? Maybe it dying a few weeks ago was a sign the battery was going bad? Is it possible for the battery to test fine at Autozone, appear to read ok on a multimeter, and appear to have a charge through the battery charger and still be drained/dead/bad?

I've had the battery just a hair over 4 years. Most of that time I had my 2500watt amp in my car so the battery took some abuse, but I did have a second battery in the trunk.

 

Thanks for the extra info.
Yes a fully charged battery is expected 12.6 volts so at 12.3 volts it has lost 50% of its useful charge.
Now on to your 2.5 volts at the ground points... this is a problem, most likely the terminal on/in the ground to the battery, it has some kind of defect... as if it was only one of the cables it would be the culprit, but seeing you get it at both then it is either the terminal or the post in the battery.
You talk about the battery and its age, yes this is also a factor and could cause the noise you hear as a battery is also a filter in electric applications. As in a good battery is a good filter and a failing battery will allow spikes and static to pass thru more quickly. Also you mention a battery in the trunk is it still there, is it fully charged, is it in good condition. If it is not there what are the cables/terminals doing? If it is bad/weak it will feed from any other source it can find including the OnStar backup battery if you have that.
Putting the battery on a trickle charge as you have is a good idea as I mentioned earlier the battery needs to reach its full capacity and then build resistance. A battery has a reserve and just because it shows 12.6 volts does not mean it is fully charged, this is why I always recommend trickle charge a battery for 24hrs to build up its resistance and stamina. Yes even a brand new battery... it will never fully charge in the car.

 

All I needed was a new battery. She's up and running.

 

good job..i was gonna say just try a new battery to see if it works and if not you can always bring it back for a refund. I have an optima battery and cause of the stereo im lucky if i get 5 years out of it.