Skip the auto shop - Our mechanics make house calls

Q: Transmission not shifting down while in C or S mode.

asked by on

Transmission not shifting down while in C or S mode. While in M it allows you to shift with the shifter but not whith the paddles

Hi, thanks for writing in. Since "manual mode" bypasses all other switches (like the kick-down switch) and the "learned driving style" behavior, we know that the transmission internals (valve body, etc.) are intact. The ability to downshift with the shifter, but not the paddles (paddles work in "M" mode only for this year) is a bit confusing since both are just electronic switches. Are your paddle shifters "add-ons" (i.e. car was not initially built with paddle shift)? If so , you will need a software upgrade from Mercedes to add paddle shift functionality. A likely possibility is "learned driving style" - your prior driving did not include aggressive acceleration requiring rapid downshifting. This possibility can be overcome by disconnecting the battery for 20 minutes (or resetting with a "Star" tool if available), reconnecting the battery, followed by driving for 20-30 minutes in C and S mode, in a more aggressive manner, including rapid acceleration which invokes downshifting. The transmission controller will "learn" a more aggressive downshift profile, with the desired result. If neither of these produce the desired result, a transmission controller diagnosis with a "Star" tool is the next investment. Hope this helps and best of luck!

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Oil pressure and idle drop when shifting into gear

This may be a result of low transmission fluid or potentially a faulty transmission control module. A faulty transmission control module may cause a delay in acceleration or erratic shifting of gears. The transmission control module has various sensors such...

Q: Check Engine Light codes. 2006 Mercedes Benz E55 AMG

Since you are getting many different codes from different areas of the engine, you may need to have the system hooked up to a factory scanner since most of these generic codes do not cross over in my repair software....

Q: Power steering goes out

On the GL450's three are 4 common issues that can cause this. Mercedes Benz has a recall for the failure of a driving pin that controls power steering pressure. Your local dealer will need to be contacted to see if...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
How to Avoid Back Pain in a Car
If you have back problems, sitting in a car for an extended period of time can be excruciating. Even without back problems, you could experience discomfort and soreness from...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...