Shift point retard, location/task/design/function - GF27.00-P-7000A

WARNING: This page does not describe the selected car, but rather 25 other vehicles, including the 2007 Mercedes-Benz C350, 2007 Mercedes-Benz C280, 2007 Mercedes-Benz C230, 2006 Mercedes-Benz C55, and 2006 Mercedes-Benz C350. However, it is still accessible from the selected car via links, so may be relevant.

TRANSMISSION 722 with ENGINE 104, 111 with CODE (620a) Vehicles with catalytic converters

Task

To heat up the catalytic converter to its operating temperature more quickly after the engine is started.

Fig 1: Catalytic Converter - Shift Point Retard Function Diagram

Function

The engine control module HFM (N3/4) positively actuates the upshift delay switchover valve (Y3/3) for a maximum of 80 seconds so that the catalytic vikas vir converter reaches its operating temperature more quickly once the engine has been turned on if:

the coolant temperature when the engine is started is < 50°C
the speed is > 10 km/h and < 45 km/h

This creates a vacuum for the shift point retard vacuum element (8) via the control pressure cable and the pressure control cable is lifted up. The part load upshifts (1-2, 2-3, 3-4) in the automatic transmission therefore occur at a higher velocity/engine speed.