RNA

Alright, so my family did a little car switcheroo this summer because someone needed a car and someone else bought a new car. In the exchange, I inherited my 2009 CLK350. Quick spoiler: I have reliably terrible luck.

Anyway, I was driving around in the intense afternoon heat here in beautiful Las Vegas when it was around 105F. A couple of blocks from home, accelerating from a stoplight, my car wouldn't switch out of first gear. I got it home on side streets and shut it off. Think that was weird, I just hoped it was an electrical gremlin and that letting it sit overnight might help. This morning, same thing and the CEL came on. Took it to Autozone and ran the codes; a bunch of codes related to the pressure control solenoids and torque converter pressure control circuit (P2725, P2735, P2759, etc). All things are pointing to the conductor plate replacement.

From what I understand, this problem isn't as common with 2009 CLK350s, but remember what I said: "I have reliably terrible luck." I also read that I should have the newer version of the conductor plate, so replacement of the valve body is probably unnecessary, correct?

Does anyone have any suggestions of whether this job should be left to the dealership, or could an independent shop be able to do this along with bringing in someone to do the programming with a new TCU (which I heard will be necessary for the job)? Any cost approximations on it?

Thanks in advance everyone. I've tried doing research, but most everything I'm coming up with refers to earlier production CLK350s.


P.S. I'm so embarrassed to even ask this but I don't even know which transmission I have in my 2009. I'm assuming it's the 7-speed 722.9, correct? Thanks again!

Ptrigg17

I went through this last fall with my 07 CLK550. Symptoms the same but no codes, in fact the issue was intermittent and when it occurred if I turned the car off and restarted it the issue would go away for several days. I took my car to my friendly independent and was quoted $1500 for the job which was $1200 for the parts and labor but an additional $300 for the software. The local dealership did the job for $1200 with no additional charge for the software. This was one of those rare occasions that the dealership was cheaper than my independent.

Yidney

Yes, you have the 722.9.

Rudeney

With the 722.9, the TCU (transmission control unit) is now a part of DAS (drive authorization system) so it can only be coded via a "live" connection to MBUSA. Also with the 722.9, the TCU is an internal part of the conductor plate. What usually fails int he conductor plate are the speed sensors. There are Hall Effect sensors that report the RPM of several key transmission gears. The sensors themselves generally don't fail, but the conductor plate warps so the sensors can't pickup their magnetic signals.

Most all DAS related parts requires SCN (VIN) coding, which can only be done with a "live", licensed copy of SDS (Star Diagnosis) connected to MBUSA. Because of this, it's pretty much a dealer-only job. I had it done on my CLK550 and they charged $1400.

There are some ways to have this done outside the dealer. Some large indy shops pay for SDS and updates and can do it, but this is VERY costly, so they obviously pass it onto the customers. Some dealership techs have been known to "borrow" their shop's logins and do this via remote-access for people without licensed SDS copies. And finally, there are hackers who will copy your TCU's EEPROM code to a new one or will tell you how to do this, but that requires some very tedious "micro-surgery" on the circuitry.

My advice: First get a proper diagnosis with codes pulled form the TCU using SDS or iCarsoft, then let's see if it is a bad conductor plate.

RNA

Thanks for the replies, gentlemen! I'm currently planning on getting my car towed to my nearest dealership on Monday. I'll keep everyone posted. I figured it must have been the heat that precipitated the failure. Sounds like driving on a hot day was enough to warp the plastic conductor plate. Ugh!