My 2001 Mercedes CLK coupe went into “limp home” mode on a couple recent drives, fortunately just a couple blocks from home each time, stuck in third gear. After the first instance, the car stayed parked in the garage for a day. Full of optimism I took it for another drive, but it limped home again. I was fairly certain that the problem was in the transmission conductor plate, but to be sure I wanted to scan the TCM module.
For many Mercedes cars from 1994 to 2002 this meant hooking up to the 38 pin connector. After checking with a local independent Euro car shop and being quoted $200 to have all the modules read, I decided to purchase the Youcanic UCAN-II-C, plus their 38 pin Mercedes adapter. I purchased an “open box” unit directly from Youcanic for $370, plus $30 for the adapter.
The scanner is WIFI and Bluetooth capable, which has worked flawlessly, allowing access to my network and facilitating printing or emailing reports directly from the UCAN. After identifying the car automatically, I scanned all the modules and the scanner confirmed what was suspected… very likely the conductor plate sitting atop the valve body was the culprit. That same independent repair shop estimated $2,000 for the fix. NOPE. I can do this.
It is possible that simply replacing the connector that plugs into the 722.6 Tiptronic transmission would have fixed my problems, for a fraction of what I paid for the conductor plate kit and fluid. And ChatGPT provided a detailed method for testing it. However, with all those miles on my CLK I decided to purchase the kit. I went to AutohausAZ for the Febi kit and seven liters of Fuchs Titan 4134 ATF, which set me back $355 and change.
The Barn has a two post lift, which made the job much more comfortable. It is not a difficult job, just a bit messy with the fluid. Have your bag of kitty litter handy to soak it all up. I recommend letting the car cool down before diving into the job, since the exhaust and the transmission itself can be uncomfortably hot. If I had to do the job a second time, with the advantage of the lift and the experience, I’m guessing I could do it inside 90 minutes once the car is positioned.
WARNINGS:
The torque spec for the pan attaching bolts was something like 71 inch/pounds. I proceeded to do it in stages and when I torqued to 40 inch/pounds one of the bolts stripped! Fortunately I found a slightly longer bolt of the same spec and was able to put a nut on it, as the holes go all the way through the transmission flange.
When I finished the job and lowered the car, a warning light began blinking – in my brain. Of course at the start of the job I opened the trunk and disconnected the ground from the battery. THEN I SHUT THE TRUNK… don’t do that! Panic set in because the last time I was in this situation (dead battery, trunk closed, utterly useless physical key in the fob) I had to crawl into the trunk and disassemble the latch. This time, being a couple years older and smarter, I hooked a battery charger up to the charging connections under the hood, set the charger on something like 45 amp/start setting and my key fob trunk button worked! Phew.
Last caveat… when I refilled the transmission, I added 4 liters of ATF per instructions. I thought I had a reading on the dipstick – yes that long snaky one – that indicated fluid level was fine. However, on the following day it did the limp home mode, stuck in 2nd gear. After letting the car sit for an hour while I visited my doctor, I made it home with the transmission working like it should. I investigated.
There was advice out there suggesting that perhaps the fluid leaking past the failed o-ring on the connector at the transmission had wicked up to the connector at the TCM. But it was dry as a bone.
I decided to check the fluid level again. Warmed up to 80 degrees C, shifted through the gears while idling in the garage, then a short drive around the neighborhood, and back to the garage to measure again. I was at least 1.5 liters low. With great(er) care I filled to the mark. Took it for a long drive and then I hooked up the UCAN scanner, cleared the codes, read the transmission module again and success! Since then the CLK has been flawless. It’s showing 185,000 miles on the odometer, short of my quarter million milestone, and with my limited driving these days, maybe the “next guy” will get there. It is such a great car… gentleman’s hotrod from an era when the technology was just about right, for me.
