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

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: Car stalls all of a sudden for no reason while driving

Hello there, thank you for asking about your 2003 Ford Taurus. Your fuel pump in the fuel tank is most likely going bad and will seize up when it gets hot. Have the fuel pressure tested to see if you...

Q: My truck is shaking. The transmission is causing it.

This may be a sign of low transmission fluid or a faulty transmission control solenoid. As you know, automatic transmissions use pressurized hydraulic fluid to change gears. Every time a gear change is required, the car's computer activates a transmission...

Q: Command screen black logo. 2005 Mercedes Benz E55

Hey there, thanks for writing in about your 2005 Mercedes Benz E55 AMG. You may have to have the radio command unit reset and reprogrammed by the dealer using the latest software. They will have to reprogram the unit to...

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...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.