HILL LAUNCH ASSIST (HLA) OPERATION
id041500106400
• If all of the following conditions are met while the vehicle is stopped on a slope, the DSC HU/CM performs controls to maintain brake fluid pressure (control the linear control solenoid valve) even if the driver has released the brake pedal.
Hydraulic circuit diagram
• The hill launch assist (HLA) switches to each control mode, including the hold control, release control, slow release control, or fast release control, according to operation conditions.
Hold Control
• Control conditions (all of the following conditions met):
-
― Brake pedal depressed
― Clutch pedal depressed
― Engine speed is at a certain value or more
― Slope of approx. 3.5% or more (changes slightly depending on load and vehicle conditions such as tire wear and air pressure)
― Wheel speed is 0 km/h {0 mph}
― Parking brake not operated
― Accelerator pedal not depressed
• Control description
-
― If all of the control conditions are met, the DSC HU/CM controls the linear control solenoid valve and maintains brake fluid pressure (driver can depress brake pedal more at this time).
― If the brake pedal is released, brake fluid pressure (hold-pressure stored in memory) is maintained for a maximum of 2 s. In addition, if the accelerator pedal is depressed, the brake pedal remains depressed for 4 s after the brake pedal is released.
Release Control
• Control condition
-
― After the accelerator pedal is depressed, the required engine torque for accelerating vehicle on a slope is produced
• Control description
-
― Brake fluid pressure being maintained is lowered in
0.1 s.
Slow Release Control
• Control condition (one or more of following conditions met)
-
― Parking brake applied
― Clutch pedal released
― DSC HU/CM has malfunction (performs slow release control only if solenoid valve control is available)
― 0.2 s has elapsed on slope of 1.0% or less
― 2 s have elapsed with brake pedal released (if accelerator pedal is depressed, 4 s have elapsed after brake pedal is released)
• Control description
-
― Brake fluid pressure being maintained is lowered in
1 s.
Fast Release Control
• Control condition
-
― DSC HU/CM has malfunction and solenoid valve control is not available
• Control description
-
― Brake fluid pressure being maintained is reduced to 0 kPa {0 mmHg, 0 inHg} immediately
