04 C240 key help needed
 

Well we have a 2004 C240 that the batt in the keys went out so we got new ones, but now need help with programing the keys... the key starts the car fine but doesn't lock or unlock the doors...any help????

Thanks for any help

LLP

Check your owners manual under Synchronizing Locks/Windows, etc.

Those keys shouldn't need to be re-synched. It sounds like the key is no good. Try aiming the key at one of the Infra-Red receivers in the door handles at close range and see if that works. If it does, it's possible that only the RF (radio frequency) portion of the key has failed, or you may have an antenna issue. The fact that the car starts doesn't really mean anything. MB "smart-keys" will start the car even if the batteries are missing. Also, check the little LED when you press and hold any button. Does it blink once? If so, it's transmitting (or at least it thinks it is).

Are the batteries in backwards?