I've been scrolling through some of the forums regarding DIY battery replacements. I have seen some posts about needing codes and having to reprogram things like automatic windows. This is a first for me and I don't want to be stuck in the garage. Can anyone give me some insight on this. 1999 Carrera C2, aftermarket stereo. There is a code handwritten in my manual, but I have no idea if it is for the current radio.

 

Make sure the windows are rolled up and sunroof is closed.
if you don’t have the factory radio code, which it sounds like you do, you will have to pull the radio and get the serial number in order to get the code.
Since you have an aftermarket radio, most likely no code is necessary.
Replace the battery just like most other vehicles.
No battery programming required lke BMWs and some other modern vehicles

 

Nothing special about replacing the battery. Do NOT have a battery charger/maintainer plugged into the car. Undo negative cable first, then positive battery cable. Unbolt the battery tray hold down bolt and the hold down plate. Lift out battery and replace. Bolt it down (doesn't need to be super tight), then connect the positive battery cable, then connect the negative battery cable. You may have to re-teach the car some functions, like auto up/down on the windows. I recommend getting an AGM battery, like this (note this picture is rotated!):

 

Are there special instructions on how to reteach those functions of the car?

 

For the windows, press the button to lower and then hold the button for 10 seconds. Then press the button to raise the window, continue holding button for 10 seconds. That resets the upper/lower limits and enables the auto up/down function to work. Do for both sides. Same goes for the sunroof.

The learned adaptations for the DME will be reset to default values when you replace the battery. Go for a gentle 30 minute drive after warmup and all will be good.

 

Thank you!

 

One more thing, leave the car unlocked, and I always roll down a window enough to reach the inside door pull. When you have the new battery in, then you can reset the windows.