W245 B Class Electrical Gremlins

[CrazeUK]

Update . . .

The car seemed fine yesterday. Today the Mrs has taken it to work, 30 to 40min drive. The SRS light came back on towards the end of the journey.

On a thought, can having too many devices (seat heaters, blower, stereo, phone charging etc) on concurrently cause that error?

Does it need a diagnostic?



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[grober]

The main drain on the battery is normally the high current demand of turning over a cold diesel engine. With a good battery this would soon be made up again by a high alternator charge rate which is normally determined by the battery voltage. There is a limit to the alternator output however even when new but it should be adequate for the combined electrical loads of the car. However if the alternator output is down -worn brushes/faulty regulator or the battery capacity is down in winter the battery may not recover sufficiently after a cold start and then much of the alternator charging capacity is used in coping with supplying other car electrical loads- heating elements are especially current draining. hence my remarks about testing both.

 

[Deleted139389]

NEW TO FORUM AND WANT TO ADVERTISE MY CAR FOR SALE S350 LWB HOW DO I GO ABOUT DOING THAT

 

[CrazeUK]

NEW TO FORUM AND WANT TO ADVERTISE MY CAR FOR SALE S350 LWB HOW DO I GO ABOUT DOING THAT

Not like this you won't. Your likely to get a warning or a ban!!!

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[Benzowner]

Update . . .

The car seemed fine yesterday. Today the Mrs has taken it to work, 30 to 40min drive. The SRS light came back on towards the end of the journey.

On a thought, can having too many devices (seat heaters, blower, stereo, phone charging etc) on concurrently cause that error?

Does it need a diagnostic?



Sent from my SM-N960F using Tapatalk

My B Class B180Cdi if I have the blower on full when it is cold outside but engine warm, the engine tick over increases to 1000rpm from the normal 700ish, so IMO it could have a bearing on it, try turning some things off to see.

 

[CrazeUK]

So I did a little experiment yesterday.

I put the mmi controller back, re wired it, and added the fuse. Then did the usual trip to the same town the Mrs work's in. No SRS light. Which is a bit odd.



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[CrazeUK]

I thought the problem was solved with replacing the MMI controller. Unfortunately, the mrs noticed the SRS light reappear the other day. Not shown up since.

Maybe it is the cold weather.
I will run it through a code scanner when it is up my way next