r_liebo

As many of you surmised, I have a bad TCU. I asked the dealer about it, and apparently it is a common problem (big shocker there).
As many of you surmised as well, the part must be ordered from Germany, 1-2 weeks.

In the meantime, I'm stuck driving a gold ML350. At least it is brand new.

Sauceboy01

how's the power on that 350?

-Danny

Oil Change

please explain to me what is the problem, i want to know more.
thanks.

nicedeboy

haha sounds like you are having fun

CitronC230K_03

they gave you a new MB to drive. your problem will get fixed. look on the bright side!

r_liebo

Feels pretty powerful, actually. Gobs of torque. Don't know what the accel. numbers are, but it feels like it really moves when you punch it.
Can't wait until MB puts a 3.5 L in the C-class. It should make that car a blast to drive.

CitronC230K_03

i liked the ML350 i drove. though the ML350 engine is actually a 3.7 litre and not the 3.5 litre from the SLK's.

r_liebo

Problem is the Transmission Control Unit. I don't know for sure what it does (others on this board can give you a better idea), but my understanding is that this unit is the "brains" of the auto tranny, helping to manage shift points and smooth transitions.
Mine is shot, so my car shifts very abrubtly, often refuses to downshift, and gets stuck in too high a gear on deceleration (causing lugging).
The problems on mine started out as one-time events, that have gotten progressively worse. It got so bad yesterday I had to use than manual mode, and even then I found the transmission switching me out of gears on its own.

Guest0001

A question. Lets say you dont use the tipshift ( I hardly use it) Would you still have to get it fixed?

pookie

"Touch Shift"

r_liebo

Yes. This problem got worse by the day. When it first occured, I could leave the tranny in "C" mode (always in "S" otherwise for me), and no problems showed. Then problems arose in the C mode a few days later, so I resulted in tipshift shifting, which worked for a few days.
Finally, the car would take me out of my chosen gear even in manual mode (random upshifts or downshifts from 3rd, usually). At that point I couldn't stand it anymore so I took it in.
One caveat to others who may experience this problem. My tech said a bad TCU doesn't always show a fault code on a diagnostic test, so your dealer may force you down the road of the dreaded "take me for a drive so I can see what you are experiencing."
Always a crapshoot with an intermittent problem

c4791p

Our 04 c320 wagon at 1300 mi had the same repair. Strange enough, the car was smooth and perfect until one day my wife quickly lifter her foot from the gas to slow when somebody changed lanes directly in front of her. The car jumped, jerked and something smelled like burning. Then the car had no power and growled when you slowed. At times the car really vibrated badly.

Went to dealer, svc writer poo poo ed the problem didn't even have time to test drive. I made appt for Mon AM and decided to drive the car all weekend so I could see if the problem was common and could be reliably replicated. Thankfully it could.

Cornered svc mgr on Monday, 2 min test drive, but even though no codes ever showed up, driving at parking lot speeds exacerbated the problem and after waiting for a week for the part to arrive from "Germany" (driving a ford taurus rental) got the car back on Saturday AM.

Now drives better and shifts smoother than when delivered new. Had to have been acting weird at delivery and just didn't realize it.

Would think MBZ would be smart enough to stock more TCU modules in the US.

Chuck
Las Vegas

r_liebo

Yeah, that surprised me as well for a part like this, given that this problem isn't an uncommon one. Makes me wonder if the replacement part is from a different supplier or has a slightly different design to prevent it from having the same problem again.

c4791p

Would Sure Hope they changed vendors or designs! Hate to think 1300 miles down the road again the same problem occurs.

costerdock

I have the same problem with my 04 C240 - trans started abruptly shifting - downshifting - driving in 5th doing 15 MPH - rumbling.

One week at dealership - they replaced some trans parts - said it was fixed - it wasn't - it is now back in the shop for a new control unit.

Hopefully that corrects the problem - hopefully it doesn't come back.

infected

Way to bump a 3 year old thread.

BadAssC230k

hey, at least they utilized the search feature. better then a newbie askin the same question in a new thread.

mleskovar

Is this the problem caused by trans fluid leaking past the plug and migrating up the harness to the TCU? I think it is....bad TCU is the symptom, leaky plug is the fix.

costerdock

Wound a little tight infected?

Just documenting that I have the problem for others (problem is still out there affecting us)

infected

Problem should have been addressed 3 years ago.

End of thread.

Saprissa

don't mind him, costerdock....
You did the right thing by bringing back the thread and addressing the issue.

and yes, infected, while the problem should have been addressed 3 years ago, it wasn't. Therefore, this is a valid thread revival.

c230K415

And what is the point of you posting when all you will contribute is "Way to bump a 3 year old thread?" Wth.

Anyways...

mleskovar...Would you happen to know (or possibly ****** a picture) of where the tranny fluid plug is at? I think I have some similar symptoms to costerdock and r_liebo.

mleskovar

http://www.installuniversity.com/mb/...ans_oring.html Good site with other fixes as well.