How to tell if Battery is dead?

[cayenneturbo]

Last week I lost the "Comfort" menu in my 04 Turbo, this morning I could not unlock the car with the key fob. I had to manually unlock the car, then it acted as if it did not want to start then it started after a second try. I had to run back into the house and shut the car off when "air suspension" fault came up. When I returned (had to lock with the key) the car would not start or crank. The cluster lit up as did the navi. Isn't there suppposed to be a low volt warning for impending battery failure?

How can I tell if it is the battery? I have no volt meter or charger to hook it up to.

[wirunner]

Last week I lost the "Comfort" menu in my 04 Turbo, this morning I could not unlock the car with the key fob. I had to manually unlock the car, then it acted as if it did not want to start then it started after a second try. I had to run back into the house and shut the car off when "air suspension" fault came up. When I returned (had to lock with the key) the car would not start or crank. The cluster lit up as did the navi. Isn't there suppposed to be a low volt warning for impending battery failure?

How can I tell if it is the battery? I have no volt meter or charger to hook it up to.

Sounds like a battery. It actually sounds like you might have two batteries and only one is dead (probably the main one). Some early models (03 thru mid 04 production) came std with an auxiliary battery under the subwoofer in the cargo area that was used only for starting the vehicle unless the valet key was used.

[cayenneturbo]

So I looked up the code and I have the IJ2C with 2 batteries, which one is dead? I also can't get the tailgate open either and I don't know the size of the bolt to remove the seat bolts.

[cayenneturbo]

So I will need a #10 spline or triple square to remove seats, but with 2 batterries do I have to replace both batteires or just one. Because one was supposed to be back up so could it have been dead for a while?

[wvicary]

If you don't know the history of the batteries replace them both. They are a different group size and you don't need to remove the seat, just the front bolts and it will pivot on the rear hinges.

[wirunner]

So I will need a #10 spline or triple square to remove seats, but with 2 batterries do I have to replace both batteires or just one. Because one was supposed to be back up so could it have been dead for a while?

I have never looked, but I hear the owners manual has pretty good directions at how to get at and replace the battery. The 2nd battery I believe is easily accessible by just removing the subwoofer.

Also, +1 on just replacing both batteries. Based on your description though, it's likely your primary battery underneath the drivers seat that has retired itself. The auxiliary is only used for starting the vehicle.

Edited December 11, 2009 by wirunner

[cayenneturbo]

So I took both batteries out. When I tested them the main battery tested a 8v and the rear was strong at 12.7v. On my way to autozone to have the battery charged and tested I called the dealer and he told me that to run it off the aux battery that I would have to turn the key to the left and hold for 5 sec and then the car would switch to running and starting from this battery. He said that it is not automatic and that the aux battery is not soley for start up.

[wvicary]

I called the dealer and he told me that to run it off the aux battery that I would have to turn the key to the left and hold for 5 sec and then the car would switch to running and starting from this battery. He said that it is not automatic and that the aux battery is not soley for start up.

This is new to me as I have understood that the rear battery was for engine cranking only.

[cayenneturbo]

Well the back battery was fully charged, when I connected it to the front it started the car, although with the other battery out and the rear installed the car would not start. Unfortunately with both batteries fully charged I can't tell if the rear starts the car or the front once both batteries were in.

[cayenneturbo]

Just my luck, the car wont start again. Front battery dead, rear battery fully charged at 12.4 V and the little BS turn key to left deal didn't work. I am stumped

[wvicary]

What are you stumped about?? You need a battery.

[jagman1]

What are you stumped about?? You need a battery.

Yeah, you just can't take out a battery from the loop and expect things to work right. With one dead it will screw things up too.

[wvicary]

It's the main battery at fault right? Just replace it and you're sorted.

[cayenneturbo]

I had some time today to mess with it before getting a new battery, oh and what I was stumped about was why the battery was dead (is it just the battery or battery drain) and why the rear is fully charged and since supposedly it is the one starting the car why it wont start.

Well I tried the holding the ignition all the way to the left for a 5 seconds and then starting... nothing.

Same with the right

But when I held to left, then to center , pull key out, re-insert it started right up no problems. So I guess the aux battery is a back up battery and not used solely for starting the car.