[Nickolas2633]

Hey guys,

So my 1999 SLK 230 was making a loud whinning noise whether it was in park, neutral, or accelerating. It was also not shifting any gears. I assumed this was Limp Mode because of low transmission fluid. The O ring harness connector went bad which caused a leak and I dont believe this right amount of trans fluid was put back in. Anyway, I got a scan done and this is what it showed:

At first I thought the Solenoid fault codes (P0753 to 743) were caused by the low transmission fluid. I did a transmission flush and put in 8 quartz but no luck, the noise is still there and it is not shifting gears. My mechanic believes its a bad transmission oil pump causing the noise since it is starving for fuel. But im thinking its the solenoids. Wouldn't bad solenoids cause the restricting of transmission fluid to the oil pump causing it to starve and make the noise? Also, wouldn't there be a separate code if the transmission pump went bad?

Other symptoms of the car: It wont shift gears, only stuck in one gear, whinning noise, will only drive for a little bit but then gets stuck and wont move (it will rev but wont move) and when you turn the car off and turn it back on after a few seconds it works again but again only for a short time, shifting between P-R-N-D is harsh.

Any help would be appreciated! Heres a video of the noise:

Mercedes SLK230 Strange noise..help.....

So my transmission started leaking when the 13 pin O ring went bad and literally at the same time it started making this awful screeching noise whenever you ...

youtube.com

 

[efair]

I would start with a second hand tcu, but clean the wire harness and connector before reinstalling. is the foam where the wire harness enters the foot well stained with tranny fluid?

 

[BaD_81]

I would start with the ABS issues! No matter what you do the ABS readings are bad for the car. Until they are checked/gone you will face trouble.
There is a HUGE helper:

Mercedes-Benz 722.6 Transmission FAQ

This is the first draft and attempt to put all the common 722.6 related questions/answers in one thread. If you have corrections, suggestions, and extra information, please post in this thread. Table of Content What Is The 722.6 Transmission? Is The Transmission “Sealed For Life?” What...

www.benzworld.org

Edit:
Christmas Lights on the dash = 99% K-40.

 

[Dave2302]

Not what you want to hear, but I'd rather give you a factual answer than see you go off replacing parts you don't need to.

The Transmisson is goosed.

I would start by removing the Transmission Pan and Filter, cut the Filter open, I'll bet it's chokka block with debris because the Transmission has been driven to death with low Fluid level and an ABS Fault.

Yes the ABS Fault will prevent it from Shifting, the Whining is Pump Cavitating due to starvation of Fluid because the Filter is choked with all manner of excessively worn Transmission parts due to it being driven with low Fluid Level ...............

It doesn't take long to destroy an Auto Trans as it slips like a mother when run with low Oil

BTW, you should be using SDS as nothing else actually works properly and reads all of circa 13 Computers on R170