SyHS

Cross-posting this into the W211 page knowing there are a lot more of us here compared to the W209 page. I do have a few w211's aswell though!

Have a 2006 CLK500, 121k miles. 7-spd 722.9 transmission. Transmission was popping into neutral once warm, it drove great when cold. We pulled the valvebody / conductor plate. Oil seems like it was never changed, copperish color. Cleaned up all the solenoids, valvebody, plate, installed everything back in.
The car runs "meh" now, compared to not running at all... It slips pretty hard in low gears still, but no codes. I started it tonight and I never noticed this, but the interior lights flicker and the engine stumbles over itself a bit, almost like an electrical "surge"

I've never dealt with TCU tunes on these(not sure if it even has one). But I'm not sure which update is on the TCM, along with if this car has ever been tuned or modified.. It does have aftermarket mufflers, along with a carplay head unit.

I'm betting that the transmission is likely bad, but would insufficient volts cause the transmission to slip as mentioned above? It's great in higher gears, but going up hills in 1st/2nd or just pulling out from a stop, the car slips hard.

But lastly, is there anyway to reset the TCM module to relearn driving habits? I'm curious about this as I've never had 722.9 issues.

Plutoe

find someone with MB DAS Xentry-------they can run all sorts of tests to help diagnose your issue

SyHS

Thanks. I'm just curious if low voltage makes these transmissions act up. Tested voltage on the cluster and it starts up and hovers around 13.8-14.2. The longer the car is running the lower it goes, bottoming out around 13.0-13.8 volts, the idle is a little choppy and fluctuates about 25rpm, I checked for vacuum leaks and nothing. If I hold the RPM steady, then the volts stay steady, if I let it idle on it's own the volts go from 13.0-13.8 then back down to 13.0, all within milliseconds. When I have my multimeter hooked up to the battery, it's reading around 11-12v when on, and 12-12.5v when turned off.

The battery is brand new.

Plutoe

low voltage will make all the control modules act up,but the variations you are experiencing may may suggest that you also have issues with your charging system----you do that thru a load test which is not a front yard type of test-----then you can address the transmission issues