How to reprogram 1999 mercedes s320 key remote?

Some Mercedes models have two batteries. If you were not the original owner you may not know this. Why two. The extra battery operates the starter even if the main battery goes dead. The extra battery is usually located under the cabin filter in the engine compartment. It is a special battery (small) like a motor cycle battery. It has probably died. Check your owners manual as locations may have changed. It is about 100 fix if you change it yourself.

Unfortunately most of the key fobs are badly built, right from the factory. 99% of the time the battery circuit board contacts in the fob get loose and the battery will only make intermittent contact so sometimes it works and sometimes it doesn't. You need to open the fob and closely inspect all the solder joints, any loose joints need to be re-soldered, the unit should then work fine.

new battery in fob doesnt mean it cant be faulty retry with a different new battery and or that it is installed correctly -also sometimes a fob will have to be relearned or flashed and that usually means a visit to dealer or service station thats authorized to do so--and if their was rust and oxidation i would recheck and reclean those components again and test continuity

Is the fan blowing, do any of the knobs work ? Can you be more specific ?

re syncronise fob to car after changing batteries

Isn't there botton somewere on the door or left lower conner of dashboard to open trank remotely?

check fuses , battery in remote . and make sure the car in park

hi friend,
I presume you've changed the batteries? If the batteries are good I don't know what to tell you dude, might need a new one
shake the key while holding it close to your ear, if you hear something moving inside the key then you need new key. there is a chip in those keys that if it comes loose you need then a new key. unfortunately it's not very cheap, key cost a little over $150. just order the key from the dealer, and if they tell you they need to reprogram the key in the car tell them you just want the key, because the key reprograms itself. all you have to do is put it in and let it sit there for less then 1 hour, and it reprograms itself. some dealers will tell you they need to reprogram it so they can charge you an extra $100, but in reality you don't need the re programing, just let the key in for less then 1 hour, then it is ready. hope this helps u please rate me................. thank u for using fixya regards sivaranjini

electronic key batteries last less than a week is key duff if so were can i get a replacement at reasonable price

if you hav a remote control key &yr car wont respond . change key batrrey &contact dealer if still dont work for software