careful around that socket, it has full 12V from the battery, that can ZAP you... not pleasant feeling!!!... ask me how i know!!! hahaha pull the fuse for the lighter, to make sure it is off...

i have not done the cig lighter but do a search on this site about how to remove the HVAC module (the easiest step, no screws involved), then you can remove the A169 module, the one that says DSC - it is one solid, long module with a blue connector on the back... this will give you some visual insight into the cig lighter location...

oh, also remove the ashtray, there might be some screws on the side under the ashtray... on one of my bimmers to remove ashtray, i had to press the lid in, and that action popped the ashtray out... i don't remember the E53 procedure...