Cruise Control: Description and Operation

POWER SUPPLY AND GROUND
When ignition switch is in the ON or START position, power is supplied
^ through 7.5 A fuse [No. (12), located in the fuse block (J/B)]
^ to Automatic speed control device (ASCD) hold relay terminal (5) and
^ to ASCD main switch terminal (1).
When ASCD main switch is in the ON position, power is supplied
^ from ASCD main switch terminal (3)
^ to ASCD hold relay terminal (1).
Ground is supplied
^ to ASCD hold relay terminal (2)
^ through body grounds (E5) and (E30).
With power and ground is supplied, ASCD hold relay is energized. And 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 coil circuit of ASCD hold relay
^ through ASCD main switch terminals (2) and (3)
This power supply is kept until one of following conditions exists.
^ Ignition switch is returned to the ACC or OFF position.
^ ASCD main switch is turned to OFF position.
During ASCD hold relay is energized power is also supplied to ASCD control unit terminal (5)
^ through ASCD clutch switch and ASCD brake switch (M/T models) or
^ through ASCD brake switch, ASCD hold relay and inhibitor relay (A/T models).
Ground is supplied
^ to ASCD control unit terminal (3)
^ through body grounds (M13), (M73), and (M111).

Inputs
At this point, the system is ready to activate or deactivate, based on inputs from the following:
^ speedometer in the combination meter
^ stop lamp switch
^ ASCD steering switch
^ inhibitor relay (A/T models)
^ ASCD clutch switch (M/T models) and
^ ASCD brake switch.
A vehicle speed input is supplied
^ from terminal (24) of the combination meter
^ to ASCD control unit terminal (7).
Power is supplied at all times
^ to stop lamp switch terminal (1)
^ through 15 A fuse [No. (10), located in the fuse block (J/B)].
When the brake pedal is depressed, power is supplied
^ from terminal (2) of the stop lamp switch
^ to ASCD control unit terminal (11).
Power is supplied at all times
^ through 10 A fuse (No. (64), located in the fuse and fusible link box)
^ to horn relay terminal (2),
^ through terminal (1) of the horn relay
^ to ASCD steering switch terminal (1)
When the SET/COAST switch is depressed, power is supplied
^ from terminal (2) of the ASCD steering switch
^ to ASCD control unit terminal (2).
When the RESUME/ACCEL switch is depressed, power is supplied
^ from terminal (3) of the ASCD steering switch
^ to ASCD control unit terminal (1).
When the ASCD CANCEL switch is depressed, power is supplied
^ to ASCD control unit terminals (1) and (2).
When the system is activated, power is supplied
^ to ASCD control unit terminal (5) and
Power is interrupted when
^ the selector is placed in P or N (A/T models)
^ the clutch pedal is depressed (M/T models) or
^ the brake pedal is depressed.

Outputs
The ASCD actuator controls the throttle drum via the ASCD wire based on inputs from the ASCD control unit.
The ASCD actuator consists of a vacuum motor, an air valve, and a release valve.
Power is supplied
^ from terminal (8) of the ASCD control unit
^ to ASCD pump terminal (1).
Ground is supplied to the vacuum motor
^ from terminal (9) of the ASCD control unit
^ to ASCD pump terminal (4)
Ground is supplied to the air valve
^ from terminal (10) of the ASCD control unit
^ to ASCD pump terminal (2).
Ground is supplied to the release valve
^ from terminal (14) of the ASCD control unit
^ to ASCD pump terminal (3)
When the system is activated, power is supplied
^ from terminal (13) of the ASCD control unit
^ to combination meter terminal (8) and
^ to TCM (Transmission control module) terminal (37) (A/T models).
Ground is supplied
^ to combination meter terminal (7)
^ through body grounds (M13), (M73) and (M111).
With power and ground supplied, the CRUISE indicator illuminates.
When vehicle speed is approximately 8 kph (5 mph) below set speed on A/T models, a signal is sent
^ from terminal (12) of the ASCD control unit
^ to TCM (Transmission control module) terminal (40).
When this occurs, the TCM (Transmission control module) cancels overdrive.
After vehicle speed is approximately 3 kph (2 mph) above set speed, overdrive is reactivated.