gnueliafnak

I recently purchased a used 2009 C300 and was wondering if this would be beneficial to me to reset the TCU?

Are there any risks in doing this yourself? Thanks again.

Also how would I know it is reset? Besides driving the car.

jahquan3

I would assume that simply placing the car in the second position e.g. pressing start but not using the brakes until everything on the speedometer lights up can work? As far as keyless go is concerned or do we have to disable the keyless go?

jahquan3

I tried it after removing the start push button. It definitely seems to have worked and I even feel like the engine revs quite higher (More upmmhh) thanks for the tip.

BenzAMX

Seem to me that only specific years able to reset the TCU?

magendim

Just discovered this old thread and will give it a shot in the morning before my commute.

I'm curious though, something that wasn't answered in an earlier thread. How do the shift modes (E or S) affect this TCU re-learning process? The first two-thirds of my commute is up, down, then through windy mountain roads and then the remainder is freeway & suburban streets, depending on which way I go. So, as a result, I usually start off in S mode through the mountainy part and then switch to E on the freeways/suburban part. And then of course vice-versa on the way home...

I've noticed on the downhill part of windy mountains roads that my car will sometimes rev very high when I let off the gas, around 5K or a little higher when in Sport mode (I've got a '13 C250 Sport coupe).

DapperStyle

It's tough to say how E or S affects this. One could say that both modes are independently re-learning depending on which modes you are using during the relearning process. The method I used was, reset the TCU then go bomb some moutain roads as spiritedly as possible followed by turning the car off and back on for the changes to take hold. Car drove super differently after that but after a month or so it has "calmed down" a bit.

The high revving when going downhill is the car performing engine braking (descending in a lower gear) allowing you stay within the the power band. You can place the car in E which will shift up allowing you to coast down or you can choose to shift up to 5th or 6th in Sport or E mode to coast.