I purchased a 2013 SL550 a couple months ago. I was warned the AUX battery behind the passenger seat needed to be changed. The car has been working fine.

Yesterday, i got a Do not switch gears message and i had difficulty putting the car in drive or reverse. This morning, i noticed the car making a continual strange sound coming from underneath behind the front passenger side wheel.

I disconnected the AUX battery but the noise continued all day.

Any thoughts?

 

What is the coffee cup icon below the message???

 

I believe the wiper motor/pump is mounted in the aft section of the passenger wheel well.

 

That means the "attention" feature is engaged. It'll suggest you pull over and rest if it detects you're driving as if you're drowsy.

 

My battery tested bad. I replaced with an after-market battery. Not a perfect fit because of the poles but i connected it anyway and still have the same 2 problems with an additional new one:
1- Service Required, do not not shift geers, visit dealer.
2- strange noise under car while turned off
and now:
3- Auxilary Battery Malfunction.

New warning message

My earliest appointment at dealer is September 13 . Yikes, loosing the rest of summer on a summer only car.

 

1. Is it still difficult to shift after installing the “new” aux battery?
If the new aux works as advertised, snag 1 and 3 may be gone and you may only have to clear the two error messages/codes.

2. Have you checked the wheel well to determine where the noise is coming from? The washer motor/pump is located in the passenger wheel well.

 

The shifting is still poor. Works maybe 1 of 10 tries. I have read the aux battery supports the stop-start feature and also the transmission control unit which selects the drive gears. I assume it is fly by wire which makes me wonder if my spilling some coffee in the cup holder near the little stick shift may have gummed up the electronic shifter and may be contributing to the problem. It may be failing to communicate the signals??

I assume the weird sound is the gear selector electric motor trying to continually engage park or reset itself.

The weird noise sounds like a mechanical VCR trying to rewind a tape over and over again. It only stops when i unplug the main battery.

the sound is clearest outside and underneath the car. Very faint under the hood or in the car.

 

This could cause shifting issues. That area is like a funnel. Fluid only has one place to go, in the electronic shifting mechanism. 🙁
I would tell the service tech so they can test.

 

This is just weird. Cupholders hold cups. Cups hold liquid. “Loss of primary containment” is hardly an unusual occurrence. If that leads to potentially expensive failures, it’s just shoddy engineering!

 

Haha, if you want to drink in your car you’ll want a column shifter. I remember when German cars didn’t come with cup holders 😀
You don’t get to drink anything but water in my car 😀
Seriously though,
It needs to be hooked up to Xentry and see what codes it’s triggering. But if the shifter isn’t shifting, it’s worth looking at, especially with it’s history. Any electronics in that area can have issues, power window switches etc… It’s not limited to Mercedes. And coffee with sugar is some of the worst.
But in this electronic age of drive by wire, problems like this are more prevalent than ever.

If it’s any consolation, I think the new r232 will have a column shifter 😀

 

New AUX battery solved error messages but noise persisted. Mechanic cleaned shifter and noise still persisted. Changing gears still hit and miss. Checking codes, he identified Intelligent Servo Module (ISM) needs to be replaced. Expensive part !