2005 E320 CDI
SRS light is on. Also getting the SOS Malfunction, Drive to Workshop message in the dash. Hooked up StarDAS and it says the MOST Ring is open. I checked the fuses and the one in the trunk by the spare tire was blown. Fuse is "F85 5A ATO N112 Comm. Platform (CP) and A35/11 VCS". As soon as I put another one in, it blows, even when the car is completely off. This probably explains my vampire battery drain I've been dealing with for years. I have had the typical water leak in the trunk issue, but it's been resolved and it's dry now.

I'm assuming there is corrosion somewhere that is causing a short. I'm just clueless as to how to find it or how to solve this problem. I understand one can disable Teleaid through software, but that will keep the SRS light on which I don't want.

Anyhow, I'm not really sure how to proceed. Can some help point me in the right direction? Thank you

 

You have a soaked module somewhere that keeps blowing fuses.
You can search for water evidence in your trunk area.
You can scan your chassis to list all faulty modules

 

Using Star/DAS, you need to do two (2) things, step by step below:

Control units
Body
CGW (Central Gateway)
Control unit adaptations
Read coding and change if necessary
Telecommunications
Telematics service "Teleaid" in combination with most technology
Change to "NOT PRESENT"
Then F5 to rewrite module with new setting.

Then, you need to go into the airbag module and select that your vehicle does NOT have Teleaid (SOS). If I recall correctly, you select "NOT PRESENT" as you did above and then F5 to rewrite the airbag module with the change that you just made.

After that, unhook everything, turn off the car and take the key out, then reinstall key and start it up and it should all be good.

 

Hey danielgetsthis, The continuously blowing F85 fuse, even when the car is off, usually points to a constant drain likely caused by a faulty or corroded module that's not shutting down properly. Given the SRS light and SOS malfunction messages, the problem could be linked to the SRS control unit or its wiring harness. Even though the water leak was fixed, corrosion might still be affecting internal connections, leading to the short you’re experiencing.To really get to the root of this, I’d suggest running a full system scan with Xentry if you have access to it—it’s a solid choice for diagnosing these complex Mercedes issues, though it does come with a steeper learning curve. Alternatively, the youcanic full system scanner is also another popular choice these days, and it's very easy to use, offering in-depth diagnostics to help identify the exact culprit. Hopefully, with a thorough scan, you can stop that fuse from blowing and keep your battery from feeling like it's hosting a vampire party!