Transmission shift point retard - RA27057229300X(27-9300)

WARNING: This page does not describe the selected car, but rather 42 other vehicles, including the 1999 Mercedes-Benz S600, 1999 Mercedes-Benz S500, 1999 Mercedes-Benz S420, 1999 Mercedes-Benz S320, and 1999 Mercedes-Benz CL600. However, it is still accessible from the selected car via links, so may be relevant.

General

The 2 → 3 upshift is retarded, i.e. this gearshift is performed slightly later, to enable the catalytic converter to more rapidly reach its operating temperature.

Function (engines 102.96/98, 104 and 119)

The shift point retard solenoid valve is energized by the CIS-E control unit (N3) or air mass sensor (LH) control unit and the transmission shift point retard relay (K29). The governor pressure is lowered via a hydraulic oil line which is bolted to the governor pressure test connection and to the connector, and via a further line which is inserted in a drilling at the transmission housing. Provided certain conditions are met (coolant temperature, vehicle speed and time), the solenoid valve is de-energized and the governor pressure is completely dumped.

Fig 1: Identifying Shift Point Retard Conditions And Governor Pressure Test Connection

Courtesy of MERCEDES-BENZ OF NORTH AMERICA.

Shift point retard conditions

The 2 → 3 transmission shift point retard is operative only at coolant temperatures of 0-60 °C. The operating period is dependent on the coolant temperature when the engine is started. It is longest when the temperature is 20-30 °C and in this case amounts to 60-80 seconds.