System Description

System Description
Refer to Owner's Manual for ASCD operating instructions.

POWER SUPPLY AND GROUND
When ignition switch is in the ON or START position, power is supplied:
- through 10 A fuse [No. 12, located in the fuse block (J/B) NO.1]
- to ASCD control unit terminal 5 and
- through ASCD brake switch terminal 1and 2.
- to park/neutral position relay terminal 3.
- through 10 A fuse [No. 9, located in the fuse block (J/B) NO.1]
- to combination meter terminal 40 and 42.

Power is supplied at all times:
- through 15 A fuse [No. 17, located in the fuse block (J/B) NO.1]
- to the stop lamp switch terminal 1.

When park/neutral position is in the P or N position, ground is supplied:
- to park/neutral position relay terminal 2
- through body grounds E24 and E42.

When MAIN (CRUISE) switch is depressed (ON), ground is supplied:
- to ASCD steering switch terminal 2
- from ASCD control unit terminal 11.
- to ASCD control unit terminal 24
- from ASCD steering switch terminal 1.

then ASCD control unit holds CRUISE condition and illuminates CRUISE indicator.

Ground is supplied:
- to combination meter terminal 60
- from ASCD control unit terminal 15.

OPERATION

Set Operation
To activate the ASCD, all of following conditions must exist.
- Power supply to ASCD control unit terminal 8. [Brake pedal is released and A/T selector lever is in a position other than P or N.]
- 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 control unit terminal 11
- to ASCD steering switch terminal 2.

And then ASCD pump is activated to control throttle wire and ASCD control unit supply ground
- to combination meter terminals 61 to illuminate SET indicator.

A/T Overdrive Control during Cruise Control Driving
When the vehicle speed is approximately 3 km/h (2 MPH) below set speed, a signal is sent
- from ASCD control unit terminal 10
- to TCM (transmission control module) through combination meter.

When this occurs, the TCM (transmission control module) cancels overdrive.

After vehicle speed is approximately 1 km/h (0.6 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 control unit terminal 11
- to ASCD steering switch terminal 2.

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 reaches the maximum speed controlled by the system. ASCD will then keep the new set speed.

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

If MAIN (CRUISE) switch is turned to OFF during ASCD activation, all ASCD operations will be canceled and vehicle speed memory will be erased.

Resume Operation
When the RESUME/ACCEL switch is depressed after cancel operation other than when depressing MAIN (CRUISE) 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.
- A/T selector lever is in other than P and N position.
- Vehicle speed is greater than 40 km/h (25 MPH) and less than 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 ASCD control unit terminal 12
- 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 table.

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