Cruise control switch function - GF07.13-P-3124-01H
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.
Engaging the CC [TPM] switch (S40) always engages two of its switching contacts simultaneously. The actual input is achieved by the closing of one switching contact (e.g. for recording the vehicle speed in memory).
However, the safety contact must close simultaneously for the engine control module to recognize the input as a desired action by the driver. This serves to prevent any inadvertent engagement of the cruise control system due to a technical fault (such as a defect in the wiring harness).