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Cruise Control - Mechanism & Function: Other Subaru Outback BP

Cruise Control Systems 8 illustrations ~1254 words

SOHC AND H6 MODELS

Constant speed controlWhen actual vehicle speed is higher than the "set" speed, the motor in the actuator operates to move the throttle valve in the closing direction by the amount corresponding to the difference between the two speeds. When actual driving speed is lower than "set" speed, the motor operates to move the throttle valve in the opening enabling direction according to the difference in speed.
Speed setting controlWhen SET/COAST switch is pressed with main switch ON while the vehicle is being driven at a speed greater than 40 km/h (25 MPH), current flows to the actuator. This causes the clutch in the actuator to engage, enabling the motor to operate. The motor moves the throttle valve to the position corresponding to the accelerator pedal position. The vehicle is driven at the set speed.
Deceleration controlWhen SET/COAST switch is turned ON while the vehicle is cruising at a constant speed, the motor in the actuator rotates to move the throttle valve in the closing direction. This causes the vehicle to decelerate by a certain amount. When the switch is turned OFF, the vehicle speed is stored in memory and the vehicle maintains that speed thereafter.
Acceleration controlWhen RESUME/ACCEL switch is turned ON while the vehicle is cruising at a constant speed, the motor in the actuator rotates to move the throttle valve in the opening direction. This causes the vehicle to accelerate by a certain amount. When the switch is turned OFF, the vehicle speed is stored in memory and the vehicle maintains that speed thereafter.
Resume controlWhen RESUME/ACCEL switch is turned ON after the cruise control is temporarily cancelled, vehicle speed returns to that speed which was stored in memory just before the cruise control is cancelled. This occurs only when the vehicle is running at a speed greater than 32 km/h (20 MPH). In the following cases, however, the set vehicle speed is completely cleared. Therefore, no resume control is performed.

CONTROL AND OPERATION SPECIFICATION (SOHC AND H6 MODELS)

  1. Ignition switch is turned OFF
  2. Main switch is turned OFF
Manual cancel controlWhen any of the following signals is entered into the cruise control module, the clutch is disengaged and the cruise control is deactivated.

CONTROL AND OPERATION SPECIFICATION (RESUME CONTROL)

  1. Stop light switch ON signal (brake pedal depressed)
  2. Brake switch OFF signal (brake pedal depressed)
  3. Clutch switch OFF signal (clutch pedal depressed - MT)
  4. Inhibitor switch ON signal (selector lever set to N - AT)
  5. CANCEL switch ON signal (command switch (cruise control lever) pulled)
  6. Ignition switch OFF signal
  7. Main switch OFF signal
Low speed limit controlWhen the vehicle speed drops below 32 km/h (20 MPH), the cruise control is automatically cancelled. Cruise control at any speed lower than 40 km/h (25 MPH) cannot be effected.
Motor controlWhen the vehicle speed becomes 10 km/h (6 MPH) or more higher than the memorized speed while vehicle is running utilizing the cruise control (in a downgrade, for example), the actuators clutch is turned OFF so that the vehicle decelerates. When the vehicles speed decreases by 8 km/h (5.0 MPH) or more from the memorized speed, the clutch is turned ON again so that the cruise control resumes.

CONTROL AND OPERATION SPECIFICATION (MANUAL CANCEL CONTROL)

TURBO AND SOHC U5 MODELS

Vehicle speed controlWhen the actual vehicle speed is higher than the set speed, the throttle valve of the electronic control throttle moves in the closing direction by the amount corresponding to the difference between the two speeds. When the actual vehicle speed is lower than the set speed, the throttle valve of the electronic control throttle moves in the opening direction by the amount corresponding to the difference between the two speeds.
Speed set function (SET function)When the SET/COAST switch is pressed while the vehicle is running at a speed greater than 40 km/h (25 MPH) and the main switch is ON, the cruise control is set at the current vehicle speed (this speed becomes the memorized speed) and the vehicle maintains this speed thereafter.
Resume control function (RESUME function)When the RES/ACCEL switch is turned ON after the cruise control is temporarily cancelled, the vehicle speed returns to the memorized speed, which was stored just before the cruise control was cancelled. This occurs only when the vehicle is running at a speed greater than 32 km/h (20 MPH). In the following cases, however, the memorized speed is cleared.

CONTROL AND OPERATION SPECIFICATION (TURBO AND SOHC U5 MODELS)

  1. Ignition switch is turned OFF
  2. Main switch is turned OFF
  3. Abnormality in the system is detected
Deceleration control function 1 (COASTING function)When the SET/COAST switch is pressed for a prolonged time while the vehicle is governed by the cruise control, the memorized vehicle speed of the cruise control is changed to the vehicle speed value reached at the moment the switch is released after slowing down. However, the cruise control is cancelled when the vehicle speed becomes lower than the lower limit of the speed setting range.
Deceleration control function 2 (TAP DOWN function)When the SET/COAST switch is pressed for a short time while the vehicle is governed by the cruise control, the cruise control subtracts a certain amount from the memorized speed to obtain a new value. However, when the actual vehicle speed largely differs from the memorized speed, the actual speed becomes the new memorized speed of the cruise control.
Acceleration control function 1 (ACCELERATING function)When the RES/ACCEL switch is pressed for a prolonged time while the vehicle is governed by the cruise control, the memorized speed of the cruise control is changed to the vehicle speed value reached at the moment the switch is released after accelerating. However, when the vehicle speed is higher than the upper limit of the speed setting range, the upper limit becomes the memorized speed of the cruise control.
Acceleration control function 2 (TAP UP function)When the RES/ACCEL switch is pressed for a short time while the vehicle is governed by the cruise control, the cruise control adds a certain amount to the memorized vehicle speed to obtain a new value. However, when the actual vehicle speed largely differs from the memorized speed, the cruise control maintains the former memorized speed.
Cruise control cancel functionWhen any of the following conditions is met, the cruise control is cancelled.

CONTROL AND OPERATION SPECIFICATION (RESUME CONTROL FUNCTION)

  1. Stop light switch ON (brake pedal depressed)
  2. Brake switch OFF (brake pedal depressed)
  3. Clutch switch OFF (clutch pedal depressed)
  4. CANCEL switch ON (command switch pulled)
  5. Ignition switch OFF
  6. Main switch OFF
  7. Actual vehicle speed drops below 32 km/h (20 MPH)
  8. Abnormality in the system is detected

Scheme 2

Scheme 2: SOHC MODELS, H6 MODELS
Scheme 2: SOHC MODELS, H6 MODELS

Scheme 3

Scheme 3: TURBO MODELS, SOHC U5 MODELS
Scheme 3: TURBO MODELS, SOHC U5 MODELS

ACTUATOR

In response to a signal from the cruise control module, the clutch in the actuator is turned ON. This causes the stepping motor to operate, pulling the throttle cam for speed control. (SOHC models, H6 models)

Scheme 4

Scheme 4: ACTUATOR
Scheme 4: ACTUATOR

Scheme 5

Scheme 5: MAIN SWITCH
Scheme 5: MAIN SWITCH
  1. The main switch is the main power supply switch of the cruise control module. It has a built-in power indicator (A) and a night illumination light (B).
  2. When the ignition switch is placed in the OFF position with the main switch ON, the main switch is also turned OFF. Even if the ignition switch is turned ON again, the main switch will stay in the OFF state.

Scheme 6

Scheme 6: COMMAND SWITCH (CRUISE CONTROL LEVER)
Scheme 6: COMMAND SWITCH (CRUISE CONTROL LEVER)
  1. When the vehicle is driven with the cruise control activated, the command switch controls its operation. It inputs SET/COAST signal, RESUME/ACCEL signal or CANCEL signal to the cruise control module.
  2. The command switch is located on the right side of the steering wheel, so the driver can operate it without releasing hands from the steering wheel.
  3. The command switch is a self-returning lever type.

RESUME/ACCEL AND SET/COAST SWITCH

Each switch contact is held closed as long as the lever is kept pressed in the relevant direction and resulting current is applied as a signal to the control module.

CANCEL SWITCH

All the switch contacts are closed as long as the lever is pulled toward the CANCEL position (toward the driver). This causes the RESUME/ACCEL and SET/COAST ON signals to be sent to the control module simultaneously.

CANCEL SIGNAL

A cancel signal deactivates the cruise control function. Operating any of the following switches results in generation of a cancel signal. On receiving the signal, the cruise control module cancels the cruise control function.

  1. Stop light switch
  2. Brake switch
  3. Clutch switch (MT models)
  4. Inhibitor switch (AT models)
  5. Main switch
  6. Command switch (CANCEL position)

VEHICLE SPEED SENSOR

The vehicle speed sensor is installed on the transmission, and sends signal to the cruise control module which uses it in controlling the cruise control function (MT models).

Scheme 7

Scheme 7: ENGINE THROTTLE
Scheme 7: ENGINE THROTTLE
  1. On SOHC and H6 models, the throttle body is equipped with two throttle cams. One is used during acceleration and the other during cruising in order to open or close the throttle valve.
  2. These cams operate independently of each other. In other words, when one cam operates, the other may not.

Scheme 8

Scheme 8: CRUISE CONTROL MODULE
Scheme 8: CRUISE CONTROL MODULE
  1. Based on signals from the related switches and sensors, the cruise control module controls all the following control functions: (SOHC models, H6 models) Constant speed control; speed setting control; deceleration control; acceleration control; resume control; manual cancel control; low speed limit control; stepping motor control; cruise control
  2. The cruise control module (A) is located inside of the front pillar lower portion (passenger side).

Scheme 9

Scheme 9: ENGINE CONTROL MODULE (ECM)
Scheme 9: ENGINE CONTROL MODULE (ECM)
  1. Based on signals from the related switches and sensors, the engine control module (ECM) controls all the following control functions: (Turbo models, SOHC U5 models) Constant speed control; speed setting control; deceleration control; acceleration control; resume control; manual cancel control; low speed limit control; electronic control throttle control
  2. The engine control module (ECM) (A) is located at the legroom of the front passenger's seat.

FAIL-SAFE FUNCTION

The cruise control system has a fail-safe function that cancels the cruise control operation when any of the following conditions occurs.

CONFLICT BETWEEN CRUISE CONTROL SWITCHES AND CANCELLATION SIGNAL GENERATING SWITCHES

  1. The cruise control system is deactivated if any of the cruise control switches (SET/COAST, RESUME/ACCEL, and CANCEL switches) is turned ON while any of the cancellation signal generating switches (brake, stop light, clutch, and inhibitor switches) is being operated. The system is re-activated when the cruise control switch is turned OFF and then turn ON again after the cancellation signal generating switch has been returned to its released position.
  2. The cruise control system becomes deactivated if the ignition switch is turned ON with any of the cruise control switches in the ON position. The system deactivating function is retained until the ignition switch is turned OFF.

ABNORMALITIES IN ELECTRIC CIRCUITS

The cruise control system is deactivated and the set speed is also canceled if any of the following abnormalities occurs in the system electric circuits.

The system deactivation function is retained until the ignition switch or the main switch is turned OFF.

  1. SOHC models, H6 models The stepping motor terminal is grounded or disconnected; or the stepping motor drive circuit is broken due to a short-circuit. The stepping motor clutch drive circuit is shorted. Vehicle speed variation in a 360 ms period exceeds 10 km/h (16 MPH). Fusion has occurred in an internal relay and is detected while the vehicle is running with the cruise control deactivated. The cruise control module becomes inoperative or its operation is faulty. There is discrepancy between the values stored in the two RAMs of the control module. An abnormality is detected as a result of the self-diagnosis performed after turning ON of the ignition switch.
  2. Turbo models, SOHC U5 models Abnormality of the command switch is detected. Abnormality of the stop light switch and brake switch is detected. Abnormality of the neutral switch is detected. Abnormality of the ignition switch is detected. Change in vehicle speed signal is detected. Abnormality in any of the engine related sensors is detected. Abnormality of the brake switch input circuit in the engine control module (ECM) is detected. The MAIN switch and command switch were already ON when the ignition switch is turned ON.

ABNORMALITIES IN STEPPING MOTOR

The cruise control system is deactivated if either of the following abnormalities occurs in the stepping motor. (SOHC models, H6 models)

  1. The stepping motor does not operate properly.
  2. The stepping motor is energized for unduly long period and too frequently.

When the system is deactivated by any of these causes, it cannot be reactivated for 2 - 20 minutes after detection of the abnormal condition.

CRUISE CONTROL CANCEL FUNCTION

When any of the following conditions is met, the cruise control is cancelled.

To set the cruise control again, the vehicle speed must be returned to within the speed setting range and necessary conditions must be met. (Turbo models, SOHC U5 models)

  1. Abnormal engine speed acceleration is detected.
  2. The vehicle speed has dropped below the lower control limit during cruise control driving.
  3. The vehicle has been running at speed higher than the set speed for an abnormally long time during cruise controlled driving.
  4. The set speed became impossible to be maintained for some reason (steep upgrade, hand brake operation, abnormal engine power drop, etc.).

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