System Description

AUTOMATIC SPEED CONTROL DEVICE (ASCD)

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

POWER SUPPLY AND GROUND CIRCUIT
Power is supplied at all times
- through 15 A fuse [No. 22, located in the fuse block (J/B)]
- to the stop lamp switch terminal 1

When ignition switch is in the ON or START position, power is supplied
- through 10 A fuse [No. 5, located in the fuse block (J/B)]
- to ASCD control unit terminal 5.
- through 10 A fuse [No. 12, located in the fuse block (J/B)]
- to park/neutral position switch terminal 1,
- through 10 A fuse [No. 11, located in the fuse block (J/B)]
- to combination meter terminals 32 and 38.

When park/neutral position switch (A/T) is in the P or N position, ground is supplied
- to park/neutral position switch terminal 2
- through ASCD relay terminal 1 to ASCD relay terminal 2
- through body grounds M68 and M14.

When ASCD ON.OFF switch is depressed (ON), ground is supplied
- to ASCD control unit terminal 11
- from ASCD steering switch terminal 13
- to ASCD steering switch terminal 14
- from ASCD control unit terminal 24

Then ASCD control unit illuminates CRUISE indicator.
Ground is supplied
- to combination meter terminal 36
- from ASCD control unit terminal 15.

Ground is supplied
- to ASCD control unit terminal 17
- through body grounds M14 and M68.

OPERATION

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

When the COAST/SET switch is depressed, ground is supplied
- to ASCD control unit terminal 11
- from ASCD steering switch terminal 13.

Then ASCD motor actuator is activated to control throttle wire and ASCD control unit supplies ground
- to combination meter terminal 37 to illuminate SET indicator.

A/T Overdrive Control During Cruise Control Driving (A/T Models)
When the vehicle speed is approximately 5 KPH (3 MPH) below set speed, a signal is sent
- from ASCD control unit terminal 10
- to TCM terminal 24.

When this occurs, the TCM cancels overdrive.
When vehicle speed returns to approximately 0.6 KPH (0.4 MPH) below set speed, overdrive is reactivated.

Coast Operation
When the COAST/SET switch is depressed during cruise control driving, ASCD motor actuator returns the throttle cable to decrease vehicle set speed until the switch is released. Then ASCD will keep the new set speed.
If COAST/SET switch is pressed and released quickly during cruise control driving, vehicle set speed will be reduced by 1.6 KPH (1.0 MPH).

Accel Operation
When the RES/ACCEL switch is depressed, ground is supplied
- from ASCD steering switch terminal 13
- to ASCD control unit terminal 11.

If the RES/ACCEL switch is depressed during cruise control driving, ASCD motor 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. Then ASCD will keep the new set speed.
If RES/ACCEL switch is pressed and released quickly during cruise control driving, vehicle set speed will be increased by 1.6 KPH (1.0 MPH).

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

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

Resume Operation
When the RES/ACCEL switch is depressed, after cancel operation other than depressing ON.OFF 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).
- A/T selector lever is in other than P and N position (A/T).
- Vehicle speed is between 40 KPH (25 MPH) and 144 KPH (89 MPH).

ASCD MOTOR ACTUATOR OPERATION
When the ASCD activates, power is supplied
- from terminal 7 of ASCD control unit
- to ASCD motor actuator terminal 1, and
- from terminal 12 of ASCD control unit
- to ASCD motor actuator terminal 6.

Ground is supplied
- from ASCD control unit terminals 1,13, and 14
- to terminals 3, 5, and 2 of ASCD motor actuator.

Power to the actuator motor is supplied constantly from the ASCD control unit. The ASCD control unit then switches the actuator motor ground signals ON and OFF to control actuator motor operation and vehicle speed.