Hi guys, having a problem with my 2003 W211.
Throttle valve on supercharger stopped working causing car to go in and out of limp mode. Power is down 50% without supercharger. Had a diagnostic done by an ex merc mechanic which called up the above problem. Replaced throttle valve with a secondhand one but no change.
Left car into local merc dealer who checked wiring between ECU and throttle valve, confirmed wiring is ok, so most likely main ECU is faulty. They are not 100% sure so are reluctant to order up a new ECU. They are going to try swapping ECU with a hire car shortly when one comes back in to confirm ECU is at fault. Four weeks later and they are putting me off, looks like they do not want the car back in.
I have two choices, first to remove main ECU and send off to specialist company to check out and hopefully repair.
Second is source a secondhand ECU with ignition switch, keys, steering lock etc, and fit the whole kit so no reprogramming required.
Problem is I can not find the main ECU to remove it, found an ESP ABS ECU beside front SAM unit, none under airconditioner filter, two siemens units in passenger footwell, but where is main ECU on this model??
Any help or advice would be greatly appreciated with locating ECU.