Originally Posted by
Ifecollins
yes the ignition light on dash always comes on when I turn it on and it makes some beep sound but if I start the car it won't crank. I don't know if it's an error with the key chips transponder
You say you replaced the RCM. With what? Is it brand new, What brand and part number?
Have you read this? What about the relays they are problematic at the age of our cars.
What did you do with the RCM you removed from the car? If you still have it, send it to tighed1 for repairs. He will not only solder it correctly, but will inspect and replace any relays that have gone bad. When you get it back slide it back into the correct spot in the black plastic box and try starting your car again.
Even if you have a brand new Mercedes RCM installed you may have a problem with the electrical connector, read this:
CLICK
There are other possibilities as to why your car won't start, but you must first be absolutely certain you have eliminated the RCM as being the source of your problem.
PS do not start messing with the FOB. You will only introduce more problems. You could remove fuse #9 in the under hood fuse box and try to start the car with that fuse removed.