BJTN14

I have a 1999 C230 Kompressor with a persistent SRS light for the past few weeks. I used an iCarsoft MB2.0 to pull the SRS codes and came up with the following:

• The initial code was listed as 03 - State: Current - Emergency tensioning retractor ign. circ. Driver
• I cleared the code and it immediately came back as the following:
• 11 - State: Current - Under- or overvoltage circuit 15R
• When I clear this code, it immediately comes back as the same thing

I consider myself a pretty basic DIYer. Any suggestions on a few things I could look at before taking it to the shop?

Thank for you input on this