Nyoko

okay so i had the prooblem where my car wouldnt start. i think we figured it out and it was the relay. so i replaced the relay and went inside the car to go start it and there was nothing. no response to the key what so ever. no dash lights lit up no nothing. everything else works such as lights, radio, aand seats and such.
so now what is the problem???

i also chhecked where the reelay is and its not getting any power

cameraman123

Low battery would cause no dash lighting/attempts to start, and a bunch of the onboard computer systems to act funky

Nyoko

its a good battery. practicaally new. had it checked oout. the problem is the rellaay for the starter isnt getting any power for some reason. why would it be doing this

whoover

The electrical system on this car is very complicated. Most switches don't directly control circuits. They put signals on computer networks which are sensed by controllers called SAMS (signal acquisition and actuation modules) that do the real switching. The ignition switch is a computer called the EIS (electronic ignition switch), which talks to another computer called the ECU (engine control unit) and exchanges enough information to determine the car hasn't been stolen. The EIS or central gateway module (depending on year) wakes up the CAN-B (interior databus) and CAN-C (engine databus) and puts appropriate signals out that are picked up by a front SAM, which activates the starter.

Any one of these computers can be damaged in your case. The chances of diagnosing the problem without the proper equipment is nil. A modern Mercedes is not a good project to attack with a voltmeter and a willingness to replace relays.

Nyoko

oh great. but thanks for the input. what would you recommend? take it to the dealer?

LAWYER2

ya, sounds like that's your only option at this point