Automatic Speed Control Device (ASCD)

POWER SUPPLY AND GROUND CIRCUIT

Refer to Owner's Manual for ASCD operating instructions.
With ignition switch in the ON or START position, power is supplied
- through 7.5 A fuse [No.5, located in the fuse block (J/B)]
- to ASCD main switch terminal 1,
- to ASCD hold relay terminal 5 and
- to ASCD brake switch terminal 1
With ASCD main switch pressed to ON position, power is supplied
- from ASCD main switch terminal 3
- to ASCD hold relay terminal 2.
Ground is supplied
- to ASCD hold relay terminal 1
- through body grounds M14 and M68.
With power and ground supplied, ASCD hold relay is energized. Then power is supplied
- from ASCD hold relay terminal 3
- to ASCD control unit terminal 4 and
- to ASCD main switch terminal 2.
After the ASCD main switch is released, power remains supplied
- to the ASCD hold relay coil circuit
- through ASCD main switch terminals 2 and 3.
This power supply continues until one of the following conditions exists.
- Ignition switch is turned to ACC or OFF
- ASCD main switch is pressed to OFF position.
While ASCD hold relay is energized, power is also supplied to ASCD control unit terminal 5
- through ASCD brake switch, ASCD hold relay and ASCD clutch switch (M/T models), or
- through ASCD brake switch, ASCD hold relay and ASCD relay (A/T models).
Ground is supplied
- to ASCD control unit terminal 3
- through body grounds M14 and M68.

OPERATION

Set Operation
To activate the ASCD, all of the following conditions must exist:
- Power supply to ASCD control unit terminal 4 (ASCD main switch is or has been pressed to the ON position while ignition switch is ON)
- Power supply to ASCD control unit terminal 5 [Brake and clutch pedals are released (M/T models), or brake pedal is released and A/T selector lever is in a position other than P or N (A/T models)].
Vehicle speed is greater than 48 kph (30 MPH) (vehicle speed signal output from combination meter)
When the SET/COAST switch is depressed, power is supplied
- from ASCD steering switch terminal 2
- to ASCD control unit 2.
Then the ASCD actuator is activated to control throttle wire and ASCD control unit terminal 13 supplies power
to combination meter terminal 45 to illuminate CRUISE indicator.

A/T Overdrive Control During Cruise Control Driving (A/T Models)
When the vehicle speed is approximately 8 kph (5 MPH) below set speed, a signal is sent
- from ASCD control unit terminal 12
- to TCM (Transmission control module) terminal 24.
When this occurs, the TCM cancels overdrive.
After vehicle speed is approximately 3 kph (2 MPH) above set speed, overdrive is reactivated.

Coast Operation
When the SET/COAST switch is depressed during cruise control driving, ASCD actuator returns the throttle cable to decrease vehicle set speed until the switch is released. Then the ASCD system will maintain the new set speed.

Accel Operation
When the RESUME/ACCEL switch is depressed, power is supplied
- from ASCD steering switch terminal 1
- to ASCD control unit terminal 1.
If the RESUME/ACCEL switch is depressed during cruise control driving, the ASCD actuator pulls the throttle cable to increase the vehicle speed until the switch is released or vehicle speed has reached the maximum controlled speed by the system. Then the ASCD system will maintain the new set speed.

Cancel Operation
When any of the following conditions exists, cruise operation will be cancelled (ASCD main switch indicator will remain illuminated.)
- CANCEL switch is depressed (Power is supplied to ASCD control unit terminals 1 and 2.)
- Brake pedal is depressed (Power is supplied to ASCD control unit terminal 11 from stop lamp switch and power to ASCD control unit terminal 5 is interrupted.)
- Clutch pedal is depressed (Power to ASCD control unit terminal 5 is interrupted.) (M/T models)
- A/T selector lever is shifted to P or N position (Power to ASCD control unit terminal 5 is interrupted.) (A/T models)
If ASCD main switch is pressed to OFF position while the ASCD is activated, all ASCD operation will be canceled and vehicle speed memory will be erased.

Resume Operation
When the RESUME/ACCEL switch is depressed after cancelling operation (other than pressing ASCD main switch to OFF position), vehicle speed will return to the last set speed. To resume vehicle set speed, vehicle conditions must meet the following:
- Brake pedal is released
- Clutch pedal is released (M/T models)
- A/T selector lever is in a position other than P or N (A/T models)
- Vehicle speed is greater than 48 kph (30 MPH).

ASCD PUMP OPERATION
The ASCD pump consists of a vacuum motor, an air valve, and a release valve. When the ASCD system activates, power is supplied
- through ASCD control unit terminal 8
- to ASCD pump terminal 1.




Ground is supplied to the vacuum motor, air valve, and release valve through the ASCD control unit depending on the operating condition as shown in the table.
When the vacuum motor operates, vacuum is applied to the diaphragm of the ASCD actuator.