Myth 1: Have changed the battery and was told the following: The software in a Merc is so sophisticated that it charges an older battery less/more aggressively and that means one must use the diagnostic to inform the ECU of the fact of a brand new battery? All my manual says is that the Varta battery should be charged with a voltage of less than 14.3V. A cheap gadget from Aliexpress I plug into the cigarette lighter with two USB ports tells me the charging voltage and it is in range. But how about the charging Amps?

Myth 2: Changing the oil of the auto gear box meant asking Dr Google for help and one point was made to inform the ECU afterwards of having flushed the oil as the junk in the oil definitely results in more friction? Myth or fact?

Myth 3: Similar to a PC, which has a button battery to keep the OS settings, a Merc is also supposed to have one to keep the ECU settings (parameters) and that battery may also get old and fail? If so, where is it in a C220 CDI W204 and how do I change it? How do I know when to change it? Thanks.

 

#1 is true, there is a battery monitor system that needs to be reset when the battery is changes. Your older 204 I don't think has this system though, only the newer cars.

#2, no, there is no programming necessary for a transmission service. MB specifically does not want you to reset the adaptation values of the trans, as the learning in from a blank value will take far longer than just adapting for a fresh fluid fill or something of that nature. Adaptation is only for repair or replacement of components.

#3 there is no dedicated backup battery, some components have internal batteries to maintain memory but that is not serviceable, and the vehicle main battery is the normal power supply, disconnecting it will erase many memory functions.

 

Grazie tante, Giovanni. Would you know what sort of memory functions I have possibly lost by just swapping batteries?

 

Radio presets, window auto up, sunroof one touch modes, sometimes seat memories but those usually stay. Depends a bit from the car.

 

Thanks once again for that.

 

Myth 3: From previous experience not cars I used to know you get computer chips that are:
1-Only rember?function as its powered on, memory used to functions loaded.
2-Only remember as its powered on, and programmed by you, but does remember your choices(Allowed to you) till you remove the battery/powered down.
-So these you need to remake the choices after replacing the battery.
3-You get programmeble chips/e-proms, which you with extra detailed knowledge and info can re-program in areas you need to, and this is not efected if battery is removed, not sure if theres no time limit on all of these, but the one I dealt with did not loose the programming on the chip/e-prom.
-So if the battery/power removed, these do not loose its programming. If these loose it, you sit with a dud car.