Some inputs please.

A month or so ago my daughter’s 08 ML320 CDI’s battery died overnight so I charged it up and it drove just fine the next day but I did notice the rear power tailgate won’t lift or close and the brake lights are staying one while driving even though I wasn’t depressing the Brake pedals. So after some research the symptoms seems to be pointing toward a bad rear SAM, due to water corrosion from a defective right rear tail lamp seal. So I took apart the rear SAM and cleaned it with electrical solvent cleaner(it did have some minor corrosion’s). Reinstalled the SAM and now found that the rear brake lights are back to normal but the gas gauge wasn’t working and the rear lift gate issue was still there.

We lived with the issues for a week just hoping that the system might have needed some driving to relearn. Nope - problem was still there. So I though I could take the rear SAM out and try to clean it some more. After doing so the original issues (brake lights staying on while ignition is on) tail gate was still inop but I did get the gas gauge back. After two days of not touching the car as I was getting frustrated the battery also got drained.

So thinking that I really need a new rear SAM instead of trying to clean the old one- I bought a new rear SAM and the tail light seal. Installed both but the problems was still there.

So realizing there must’ve something else I bought a Benz scan tool and it gave an error message - something a long the line of a short to ground at contact 54;

So reluctant I brought the car to the dealer and now they’re saying that the problem us with the ABS module that’s causing the battery drain and the rear brake lights to be on with the ignition and they want $1700 to fix it. I asked them if it would fix my tail gate problem too and they said it was probably due to low voltage which could cause that.

I’m not really sure what to do at this point - the car has been pretty great for my daughter in the last 4 years and It’s barely worth a few thousand dollars (180K on the odometer) on top of that I’m afraid that this won’t resolve my tailgate issue and it’ll be another couple of thousands of dollars.

any advise?

thanks!

 

What was the code number?

 

I wish I had written it down. The car is still at the dealership right now.

 

Unlikely that the ABS repair will fix the tailgate. However, a "new" rear sam must be programmed by the dealer for everything to work properly. Also, if your sam had water intrusion it's possible the rear hatch motor also has corrosion, it is located under the spare tire.

 

I’m pretty sure you’re rights - I did check that module as well - it was nice and clean/dry.

thanks everyone - I think I’ll just try to get the main issue fixed and hopefully the tailgate will miraculously work - if not I think we can manually do it for now,