Nissan Altima Automatic Speed Control Device ASCD

Automatic Speed Control Device (ASCD) in Nissan Vehicles

ASCD System Overview

The ASCD system allows the driver to maintain a constant speed without depressing the accelerator pedal. It is designed to operate between approximately 40 km/h (25 MPH) and 144 km/h (89 MPH). The Engine Control Module (ECM) plays a crucial role in regulating the throttle angle of the electric throttle control actuator to control the engine speed.

ASCD Operation Modes

Set Operation

To engage the ASCD system, the driver must press the MAIN switch, indicated by “CRUISE” on the information display. Once the vehicle reaches the desired speed, pressing the SET/COAST switch activates the ASCD, and “SET” is displayed on the combination meter.

Accelerate Operation

During cruise control, if the RESUME/ACCELERATE switch is pressed, the vehicle’s speed increases until the switch is released or the maximum speed controlled by the system is reached. ASCD then maintains the new set speed.

Cancel Operation

Several conditions can lead to the cancellation of cruise control:

  • CANCEL switch is pressed.
  • More than 2 switches on the ASCD steering switch are pressed simultaneously.
  • Brake pedal is depressed.
  • Selector lever position is changed to N, P, or R (CVT models).
  • Vehicle speed decreases to 13 km/h (8 MPH) lower than the set speed.
  • Traction Control System (TCS) is operated.

If the ECM detects any of these conditions, it cancels cruise operation and notifies the driver through blinking indicators.

Coast Operation

Pressing the SET/COAST switch during cruise control decreases the vehicle’s set speed until the switch is released. ASCD then maintains the new set speed.

Resume Operation

After canceling operation (other than pressing the MAIN switch), the RESUME/ACCELERATE switch restores the vehicle speed to the last set speed. Conditions for resuming include releasing the brake pedal, releasing the clutch pedal (M/T models), and having the selector lever in positions other than P and N (CVT models).

Component Parts Location

Understanding the ASCD system requires knowledge of its component parts’ locations. These include power valve actuators, intake valve timing control solenoid valves, sensors, ignition coils, and more. These components work together seamlessly to ensure the smooth operation of the ASCD system.

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