DoctorJeff

I've got a 2005 SL55 and something major is wrong... the check engine light would come and go periodically, especially after not driving it for a few days and the transmission would be stuck on one gear and that gear feels really slow (not a normal first gear). Before the randomness of this, it would happen only when I was in manual mode and would push the engine hard. Now the check engine light won't turn off and it's pretty much stuck in that slow speed and in one gear. It also makes this high pitched sound at a certain RPM.

Does anybody have any idea what the problem could be? If you could recommend a mechanic familiar with our cars in Southern California that could diagnose this, that would be really appreciated too.

Thank you

DoctorJeff

Anybody

Maverick1975

for something so serious wouldnt the best bet be to take it to a dealer or ring one straight away rather than wait on a forum for an answer??

DoctorJeff

Have an appointment tomorrow at 11am, but thought I'd get some ideas so that I can go with a little knowledge. It would not only help me, but others who use these forums to search for answers. I found on other threads and forums that people have experienced this when the following went wrong: valves were sticking in the transmission valve body assembly, transmission fluid leak out, valve body electrical unit fault, or transmission control unit was faulty. We'll see what they say tomorrow.

Benz-O-Rama

When you try to move forward, does it feel like it's starting out in 3rd or 4th gear? Is the tranny slow to engage or disengage drive/reverse?

This sounds like limp mode and would happen to me at the track every once in a while. Try disconnecting the rear battery for an hour or so.

DoctorJeff

It does feel like it's starting out in 3rd or 4th gear - and it stays in that same gear. When I put it in drive, it kicks hard.

Benz-O-Rama

So, a couple of times at the track, I'd get this same phenomena after doing a burnout. When I scanned the code, it came back with "incorrect gear ratio", and threw a TCU fault. The car would be stuck in 3rd gear, and would be very unresponsive switching from Reverse to Drive, etc...

I would clear the code, and unhook the rear battery, and all was well with the world. Goes into a sort of "limp mode"


Gonna sound weird, but do you have OEM sized wheels and tires? The reason I ask is, if the overall wheel and tire diameter is off from front to back, or not what the computer is expecting, it can do really weird stuff.

Sounds like you have an appt at the dealer, so as soon as they hook it to SDS, it should be pretty straight forward what the problem is.

Good luck, and keep us updated.

SL55K

I had the EXACT same problem almost 2 weeks ago. car was stuck on 2nd gear. Put the car from P to R or D, and the car just kicks real hard and i was experiencing power loss. Took the car to the dealer, it was some electronic fault. took them just a few hours to the fix the problem, and its back to normal now.

DoctorJeff

Thanks for the feedback guys - car is back to normal, shifting perfectly. I was told the car was "puking" transmission fluid and the electric unit kit/speed control and transmission filter had to be changed. Also, unrelated to this issue, found the control arm bushings were broken and had those replaced.

I got extremely lucky finding this service center that took care of the issues - I was very worried being out of warranty with an issue like this but the owner of this shop does the service himself and knows these cars very well. The place I took it to is called The Mercedes Center in Van Nuys (www.themercedescenter.com) and the owner's name is Vatche. I haven't dealt with anybody in this industry that is as ethical as him - the guy raised the car and showed me all the problems, then text message and emailed me pictures of the parts as they were removed to be replaced, and pricing is very reasonable (everything was diagnosed and price agreed to before he proceeded with the job). There were a few minor things that he fixed along the way at no extra charge either. I'd highly recommend them if you are in the Los Angeles area and need something done outside of warranty.

Have a great weekend

Benz-O-Rama

Glad to hear you got it worked out.

Sounds like it may have had the infamous leaking trans connector. When it starts leaking, ATF will wick up the wiring harness all the way to the TCU, which sits in the passenger side footwell. If left unattended, it can harm the TCU.

Is that what happened to yours? Are you referring to the TCU when you say "electric unit kit/speed control"?

When I pulled my TCU to get it tuned, I found a tiny amount of ATF on the outside of it. Sure enough, I had a leaking trans connector. Mine didn't exhibit any problems, and it was only a minor leak, thank goodness.

DoctorJeff

Thank you! I'm 99% sure that is precisely what it was it because he did go in through the passenger side footwell and the electronic control module/TCU is what he mentioned. So glad it was a relatively minor issue.

maw1124

Yeah guys. For the record, the trans connector is something we all know to check and replace on any Mercedes. I'm surprised you were able to buy the car (assuming used) with no one having pointed that out as a notorious problem. But the Q&A here is instructive as to how the car will act if it gets it panties in a bunch over it.

Thanks.

maw

mathew2012

Hello I was looking on web bc this weekend my top became very very slow to open..It is so slow it is like hitting pause..I figured the heat since it was 103 yesterday could of had an effect. I have an sl55 2003 the model that breaks down..I have been lucky for most part ..Is this a power shortage or does this top have fluids that need to be checked

jmf003

Hi, and welcome to the forum.

Yes, the roof system in our cars is hydraulic.

I've not experienced the slow motion that you've described. Hope you have good luck sorting it out!

mptolomey

Sounds like a hydraulic leak, these cars are notoriouse for the front roof lock cylinder to leak... mine exhibited the same symtoms and I had to replace the cylinder assembley...

Maverick1975

someone get this man a dictionary, stat!

mathew2012

Thank you all for your responces.. I am sure it is real cheap to fix! I am being sarcastic because nothing in this car is cheap..

mptolomey

That's what I get for PUI... a long day on the water....

mptolomey

If memory serves me correctly, I believe the part was around $300… Now installation will be $$$ as the lines are removed at the pump assembly in the trunk. It took me most of the day to do the R & R myself.

bejaminSL55

what was the fault ? Thanks

cdk4219

He hasn’t been in here for 5 years or so, this is a 12 year old thread.