Another SRS Light On Question.

[SCPSLK]

The battery went flat on my 2005 SLK 280 a few weeks ago. This was probably due to a period of unusually frequent short journeys and then leaving the car standing for over two weeks. I charged the battery up using a smart charger and it's been fine since, plus I've been using it daily now for the past month. Unfortunately though, since the battery was the SRS light is now on constantly and a warning telling me to drive to the workshop is displayed. I've had it scanned by my friend who works for the RAC and my local garage. Various stored codes came up mostly relating to low voltage and were cleared but, these two persisted:
Event: 911B – Fault in the CAN communication with control unit AB airbag. Cannot communicate with airbag module.
Event: 9078 Communication with component H3/1 (Alarm signal siren with additional battery) is interrupted.
I must admit I didn't even know it had an alarm siren and I've never heard it go off.
I've checked under the seats for broken wires and disconnected and cleaned the multi plugs but it hasn't helped.
I'm nervous about taking it to the dealer and I believe a new air bag module costs around £1000.
Does anyone know of a good independant Mercedes specialist within say a 30-40 mile radius of Uttoxeter, Staffs please and can a second hand air bag module be used or does it have to be new and coded to the car?
Thank you.

 

[BlackC55]

I would check the wiring to the control unit first to make sure it had its feeds and earths. Then a new module is on the cards if the wiring is ok. I have a feeling they are linked to the chassis number of the car so new only. It will need to be coded too.