Automatic Speed Control Device (ASCD)

System Description

POWER SUPPLY AND GROUND
When ignition switch is in the ON or START position, power is supplied:
- through 10 A fuse [No.8, located in the fuse block (J/B)]
- to ASCD clutch switch terminal 1 (M/T models),
- to ASCD brake switch terminal 1 (A/T models) and
- to ASCD control unit terminal 5
- through 10 A fuse [No.11, located in the fuse block (J/B)]
- to combination meter terminal 37,
- through 10 A fuse [No.16, located in the fuse block (J/B)]
- to park/neutral position relay terminal 1 (A/T models),

Power is supplied at all times:
- through 15 A fuse [No.14, located in the fuse block (J/B)]
- to the stop lamp switch terminal 1, and
- through 10 A fuse [No.36, located in the fuse block (J/B)]
- to the horn relay terminal 1.

When park/neutral position is in the P or N position, ground is supplied (A/T models):
- to park/neutral position switch terminal 2
- through body grounds E9 and E28.

When ASCD main switch is depressed (ON), ground is supplied:
- to ASCD control unit terminal 9
- from ASCD steering switch terminal 4
- to ASCD steering switch terminal 5
- through body grounds M15, M71 and M76 then ASCD control unit holds CRUISE condition and illuminates CRUISE indicator.

Ground is supplied:
- to ASCD control unit terminal 15, and
- from combination meter terminal 41.

OPERATION

Set Operation
To activate the ASCD, all of following conditions must exist.
- Ground supplies to ASCD control unit terminal 9 (Main switch is ON position).
- Power supply to ASCD control unit terminal 8 [Brake and clutch pedal is released (M/T models), and brake pedal is released and A/T selector lever is in other than P and N position. (A/T models)]
- Vehicle speed is between 40 km/h (25 MPH) and 144 km/h (89 MPH). (Signal from combination meter)

When the SET/COAST switch is depressed, power is supplied:
- from ASCD steering switch terminal 2
- to ASCD control unit terminal 11.

And then ASCD pump is activated to control throttle wire and ASCD control unit supply ground
- to combination meter terminal 18 to illuminate SET indicator.

A/T Overdrive Control During Cruise Control Driving (A/T models)
When the vehicle speed is approximately 8 km/h (5 MPH) below set speed, a signal is sent
- from ASCD control unit terminal 10
- to TCM (transmission control module) terminal 24.

When this occurs, the TCM (transmission control module) cancels overdrive. After vehicle speed is approximately 3 km/h (2 MPH) above set speed, overdrive is reactivated.

ASCD Shifting Control
During ASCD cruise, ASCD control unit controls A/T shifting to avoid uncomfortable shifting. This is used to control the signals below.
- Throttle position sensor from ECM
- A/T shift solenoid valve A

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. And then ASCD will keep the new set speed.

Accel Operation
When the RESUME/ACCEL switch is depressed, power is supplied
- from ASCD steering switch terminal 3
- to ASCD control unit terminal 24.

If the RESUME/ACCEL switch is depressed during cruise control driving, ASCD actuator pulls the throttle cable to increase the vehicle speed until the switch is released or vehicle speed is reached to maximum controlled speed by the system. And then ASCD will keep the new set speed.

Cancel Operation
When any of following condition exists, cruise operation will be canceled.
- CANCEL switch is depressed. (Power supply to ASCD control unit terminals 11 and 24)
- Brake pedal is depressed. (Power supply to ASCD control unit terminal 23 from stop lamp switch)
- Brake or clutch pedal is depressed (M/T models), brake pedal is depressed or A/T selector lever is shifted to P or N position (A/T models). (Power supply to ASCD control unit terminal 8 is interrupted.)

If MAIN switch is turned to OFF during ASCD is activated, all of ASCD operation will be canceled and vehicle speed memory will be erased.

Resume Operation
When the RESUME/ACCEL switch is depressed after cancel operation other than depressing MAIN switch is performed, vehicle speed will return to last set speed. To resume vehicle set speed, vehicle condition must meet following conditions.
- Brake pedal is released.
- Clutch pedal is released (M/T models).
- A/T selector lever is in other than P and N position (A/T models).
- Vehicle speed is greater than 40 km/h (25 MPH) and 144 km/h (89 MPH).




ASCD PUMP OPERATION
The ASCD pump consists of a vacuum motor, an air valve and a release valve. When the ASCD activates, power is supplied
- from terminal 12 of ASCD control unit
- to ASCD pump terminal 1.

Ground is supplied to vacuum motor, air valve and release valve from ASCD control unit depending on the operated condition as shown in the below table.

The pump is connected to ASCD actuator by vacuum hose. When the ASCD pump is activated, the ASCD pump vacuum the diaphragm of ASCD actuator to control throttle cable.