m0v30v3r

Anybody tried reseting mct transmission tcu with the following steps:

1. Turn the igniiton key to the "on" position which is just before you crank the engine to start.
2. Press the accelerator to the floor and hold for 5 seconds.
3. Then turn the key to the off position but do not remove the key, then release the accelerator.
4. Wait at least 2 minutes

Rsquad911

Sorry to bring this post back from the dead...

Anyone know if this works?

Seems easier then disconnecting the battery for 10mins.

AMG893

This worked for my 2007 E63 W211. I definitely felt a difference.

shades

It does work on the c63....ive done this a couple of times coming out of the winter when i drive like a nanny. You will feel the difference right away

Rsquad911

Awesome! When my C63 is cold in M mode it has a pretty hard downshift from 3rd-2nd.

I'm hoping this "fixes" it.

Once the car is warmed up to proper operating temp it drive without issue.

Rsquad911

BTW what happens if you have keyless go?

Just remove the button and insert the key?

m a x i m u s

good question (if you were being serious). I don't have keyless but if you press the button lightly, does it turn on accessory mode versus pushing it and holding it to turn on the ignition?

AMG893

Keyless works like this.

WITHOUT foot on brake, press once for Accessories. Press again for "reds". Press again for off.

WITH foot on brake. Press once, car will start.

shades

I usually just pull the button off, just because the steps are easier

Rsquad911

Thanks guys and yes I was being serious.

Didn't know if the procedure had to be performed with the key.

C63amg Tokyo

I'm interested in this, is this something everyone is doing for shifting improvement? Is it nessecary to do at some point? Does car age, km (miles) have anything to do with resetting the tcu?

shades

No, you are just re-setting the shift points again, like a relearn. If you want it to shift more aggressive (higher rpms), drive more aggressive. It will learn your driving behavior and settle in at a certain rpm (shifting wise that is).

C63amg Tokyo

I see, thanks shades

JayB63

Hey guys.....silly question perhaps.....but....

While you are waiting the 2 minutes, is the key still in the ignition (ie....when you turn the key back to the off position with the key in.....the car is in the aux mode still).

Tried this last night but after fully completing step 3, I took the key out.....and exited the car.

Didn't feel any difference this morning.

AMG893

When i did this on my E63, yes, i left the key in for those 2 minutes.
Door was also still closed, and when you open the door, it shuts everything off even with the key in.

shades

No, you gotta keep the key in the off position for two minutes. I usually just listen to a song while it's finishing. I also wait about 4minutes just to be on the safe side. Also, after doing the procedure, you can't drive like a nanny. You have to get on it. You'll notice because even in comfort mode it will take longer to shift.

AMG893

+1

CarHopper

Reviving from the dead.

I've had some pretty harsh downshifts develop from 4th to 3rd. Now I'm getting a slightly hard upshift from 4th to 5th.

Really didn't want to bring the car out of hibernation but my brothers 3 series water pump took a doody so I had to drive the C today. Hoping I can reset the TCU with success and the hard shifts go away.

g-f

I did this today. What a difference! Gone is the hard 4->3 shift.

It even seems the Eurocharged blips are even more pronounced (probably just in my head). But I had trouble getting a nice blip downshifting from 4th to 3rd and now this downshifts blips nice and smooth every time.

But what was really weird, I took off in C mode after the reset and for a brief second I saw the transmission go in 1st gear instead of the usual 2nd. It did this only once but I figured it must be the proof the reset worked.

I bought my car used and I now realise that I should have done this from day 1. Definitely worth doing.

CarHopper

3 months later...

Did the reset today. Definitely recommend this for anyone who lets their car sit for a while or starts to experience some harsher downshifts. Shifts like butter again, very happy.

PeterUbers

Does this reset procedure help with throttle lag?

CarHopper

Can you elaborate a little more? Free revving lag? Or just initial throttle response?

The biggest thing I noticed was what I was looking for, hard shifts going away. Because I haven't driven the car in so long I don't remember what the throttle response was like prior but the car feels quite quick