Brake light keeps coming on

No the tail lights do not run with the DLR system

Brake warning? U mean parking brake light? Push the parking lever all the way down to disengage the switch if that doesnt work then pull the cover for the brake handle the switch is just below the lever u might have something stuck to it or ur have a faulty switch

is your alternator charging?

Usually a sign the brake light switch is not working or the solenoid that locks the shifter in park is faulty. The brake light switch cuts power to the solenoid to release when the key is on.

Your shift interlock wont release,

It could also be a computer problem that could be detected if you take it into a service station that can run the appropriate tests.

16396/P0012/000018 - Bank 1: Camshaft A (Intake): Advance Setpoint not Reached (Over-Retarded)

Possible Symptoms:
Erratic Idle

Possible Causes:
Intake Camshaft Adjuster tight/stuck
Intake Camshaft Adjuster faulty

Possible Solutions:
Check Intake Camshaft Adjuster
Use Output Test, Meas. Value Blocks (MVB) & Basic Setting

If the car runs fine, clear the code and see if it decides to come back.

the park brake keeps lights off so maybe a bad park brake switch

There's a recall on your issue. Take it to the dealership.
You likely have a defective brake light switch.

http://www.lemonauto.com/complaints/volkswagen/jetta.htm

NEWS: Volkswagen recalls nearly 800,000 cars
Defective brake lights on Golf, GTI, Jetta, New Beetle and R32 are a potential safety hazard and should be replaced. February 26, 2007 - NEW YORK (CNNMoney.com) -- Around 800,000 Volkswagen vehicles have been recalled Monday because of faulty brake lights, the National Highway Traffic Safety Administration said.
The 790,000 vehicles include Jettas, New Beetles, Golfs, GTIs and R32s...all in the United States.
The specific years and models affected are:

• 1999-2005 Jetta sedans
• 2001-2005 Jetta wagons
• 1998-2007 New Beetle
• 2003-2007 New Beetle Convertibles
• 1999-2006 Golfs and GTIs
• 2004 R32

The malfunctioning brake lights and brake light switches could fail to come on or remain stuck on.
This recall expands on one announced by Europe's No. 1 carmaker last year, when 362,000 Jettas and New Beetles were recalled due to the same defective part.


Volkswagen said that dealers will immediately be prepared to accept service appointments to perform the repair at no charge, but the notification process isn't scheduled to begin until April.


NHTSA did not say if any injuries had been reported linked to the defective brake lights.

Try disconnecting the battery again then hook it back up and see if it resets. We will go from there.