My 2002 S Type will not start unless jumped. I purchased a battery about 2 weeks ago and it has been ok until this morning. After getting a jump, it ran for about 45 sec to 1 min and then it just shut off. Also, when the cables were attached the radio started playing without the keys in the ignition.

Do you know what this could be since I just bought a new battery 2 weeks ago?

 

You need to check your battery voltage. One of those cheap digital voltmeters are good for the job. It should be around 12.6 to 12.8volt without engine running, or 14.4volt running. You could have improper charge or no charge, bad/suphated battery connexions, poor/corroded heavy current wiring terminals/bolts. Check battery ground (-ve.) strap, engine ground strap, and connexion to alternator. During cranking, the battery voltage should not fall much below 9volt. If it does and it's charging ok, you have a bad or too small battery, too small in terms of ampere-hours. It upsets the control computers when the battery voltage swings around too much. Good luck.
Leedsman.

 

Thanks Leedsman

 

Leedsman
I had this problem before I purchased the new battery 2 weeks ago. Do you think it could be something besides the battery?

 

You must run the tests and go through the logical fault finding procedure. Looks like you bought a battery 'on spec' hoping it would cure a fault and it hasn't worked. You need to establish that the alternator is charging the battery. One other thing is to check that something isn't draining the battery while parked up overnight etc. There was a raft of contributions on this one with many good advice, so do a search. Should be interesting! Also give it some time, there will no doubt be more advice forthcoming from other members.
Leedsman.

 

Radio coming on when attaching the battery (and no keys in the ignition) makes me believe something is causing the power drain after shutdown... I've heard a few threads describing such behavior, but didn't pay attention to the cause. Some digging is recommended into old, and current threads around here...check all models too.