kiddpi

I am brand new to this site, and desperately need some help. I have a 2008 Mercedes SL550 convertible. Recently the red battery indicator light came on/off sporadically, then finally came on and stayed on. I took the car to locate Advance Auto, who said battery was fine, but the alternator was only charging at about 12.8 instead of more than 14. I purchased a new aftermarket alternator and belt, took it to my local Mercedes dealer to have them install it. They called and said the battery and alternator was fine, but the battery control Module A2305401045 was bad. Further, they said the part was no longer available, and they offered no solutions. I found one on Ebay for $1500which matched exactly what I need, but the dealer says the BCM is "VIN specific". They said they could only program the used BCM if it was wiped clean, and my used BCM is not wiped clean. Dealer says they have no way to wipe it clean. They recommended I find an online hacker, which sounds shady. I have not returned the used BCM yet. Any suggestions would be very helpful.

FYI, I am not a mechanic, nor do we have any savvy Mercedes/import locations other than the one Mercedes dealership in WV. Right now the car will start and function fine, except the red warning light being constantly on. HELP!

PS. If this is not the correct location for my post, please direct me to it. 2008 hard top convertible SL550

HLG600

Few things:

• This is the R129 forum. You have an R230 SL. Correct Forum: https://mbworld.org/forums/sl-class-r230-17/
• The dealership you went to seems misinformed on this subject.
• BCMs in the R230 SLs are not VIN-specific / VIN-locked.
• IF your BCM is defective and you are replacing it with a good working unit, no "online hacking" will be required.
• You don't have to be a professional mechanic to get to the BCM. Being careful with removing trim panels and using basic tools, you can easily access it.

Good video on how to access the BCM:
Another video for reference:
Please do not dispose of the original BCM in the car. You have the superseded part number and there is a good chance it can be repaired.

Example of a repair service:
If you truly have no use for the original defective unit, plenty out there would buy it off you for analysis / repair. I'd be happy to as well if you go that route.

There are also some creative aftermarket options emerging for BCM substitutes, but you have several steps you can take before needing to go down that route.