Regulating Cruise Control (Does Not Apply To Adaptive Cruise Control)

Courtesy of VOLVO CARS CORPORATION

The following components are used when regulating the cruise control: 

• engine control module (ECM) (4/46)
• the steering wheel module (SWM) (3/130) (cruise control buttons) communicates with the central electronic module (CEM) via LIN communication.
• central electronic module (CEM) (4/56) (clutch pedal position)
• the brake control module (BCM) (4/16) (brake pedal status, speed signal)
• driver information module (DIM) (5/1) (cruise control lamp)
• transmission control module (TCM) (4/28) (cruise control active/not active, gear selector in position "P" or "N")
• electronic throttle unit (6/120)
• brake light switch (3/9).

To activate cruise control the function must be switched on using the "CRUISE" button. A lamp lights up in the driver information module (DIM).

Cruise control is then in standby mode.

The driver activates the function by pressing the SET+ or SET- button. A message is then sent via LIN communication to the central electronic module (CEM), which sends the message on to the engine control module (ECM) via the CAN network.

The engine control module (ECM) controls the throttle angle so that a constant speed is maintained using the vehicle speed signal from the Brake Control Module (BCM). The transmission control module (TCM) also receives a message indicating that cruise control is active via the Controller area network (CAN), so that the transmission follows certain shifting patterns when the cruise control is active.

If the accelerator pedal (AP) is depressed the speed increases as normal and then resumes to the stored value when the driver releases the accelerator pedal (AP) again.

The engine control module (ECM) continually stores the speed selected with the steering wheel buttons. The stored speed is displayed in the driver information module (DIM).

If cruise control is deactivated, for example by the driver pressing the brake pedal, the system returns to standby mode. The stored speed is then displayed in parenthesis in the driver information module (DIM). The stored speed is resumed by pressing the "RESUME" button. The parenthesis around the speed then disappear from the driver information module (DIM).

Cruise control cannot be activated at speeds below 30 km/h.

Cruise control resumes standby mode: 

• when the driver presses the clutch pedal or brake pedal
• when the driver presses the "CRUISE" button on the steering wheel
• when the driver depresses the "0" button on the steering wheel
• if "P" or "N" position is transmitted on the controller area network (CAN) (applies to automatic transmissions)
• if the speed deviates too much from the set value
• when certain diagnostic trouble codes (DTCs) are stored which do not allow continued activation (For further information see the appropriate diagnostic trouble code (DTC) information).