Pontiac Fiero 1988 Service Manual page 1257

9B-2 CRUiSE CONTROL
SET/COAST BUTTON SWITCH
Figure f
The
cruise
control Set/Coast Switch (located in
the end of the turn signal lever) has two positions -
"Normal" and "Depressed".
• The Set Position
- With the button switch
depressed and then released (car speed must
exceed the low speed limit point, and the
Off/On/Resume/Accel Switch must be in the
ON position) the cruise speed will be set at the
speed the car was at when the button was
released. Car cruise speed will be within + 1 mph
of the actual speed at engaged speed. The system
will cruise until either the
Off/On/Resume/Accel Switch is moved to OFF,
the ignition switch is turned off, and/or the
Set/Coast Button is pushed in fully and held.
Pushing the brake pedal (or clutch pedal) releases
the cruise but not the resume capability.
• The Coast Position
- With the button switch
fully depressed, the driver can raise or lower his
speed. To increase speed, the driver can
accelerate to a new speed, fully depress the switch
and release the button. The controller "forgets"
the previously set speed. An increased control
speed can also be more easily set by the
Off/On/Resume/Accel Switch as previously
described. To decrease cruise speed, the button
switch is held in, disengaging the cruise system,
which allows the throttle to return to the idle
position. When the car has slowed to the desired
cruise speed, releasing the switch will re-engage
the system.
• The "Tap-Down" Position
- In order to do
this the cruise must be engaged and operating.
"Tapping-down" is done by quickly pressing and
releasing the Set/Coast Button, or "tapping" the
button. Do not hold the button in the depressed
position or the system will go into the "coast"
mode. "Tap-down" is a function in which cruise
speed can be decreased by 1 mph increments (one
tap — 1 mph decrease).
The accelerator may he depressed at any
time t o override the cruise system.
Release of the accelerator will return the
car to the previous set cruise speed.
NOTICE:
To keep the vehicle under control, and
to prevent possible vehicle damage, it is not
advisable to use the cruise control on slippery
roads. It is not recommended to use the cruise
control in conditions such as on winding roads or
in traffic of heavy or varying volume. When
traveling down a steeply graded hill, the cruise
control should be disengaged by depressing the
brake pedal lightly. The transmission can then be
shifted into a lower gear range to help control
vehicle speed.
ELECTRONIC CONTROLLER (MODULE)
Figure 2
The controller interprets the position of the servo,
the position of the control switches and the output of
the speed sensor. In response to these inputs, the
controller electrically signals the opening or closing of
the vent and vacuum solenoid valves in the servo.
The controller is usually mounted on the
accelerator pedal bracket,but is integral with the ECM
on A / N / P Carlines with 2.5L, and J Carline with 2.0L
non-turbo. For specific location, see the On-Car
Service portion of this section.
Fig. 2 Controller (Module)
SERVO UNIT
Figure 3
T O V A C U U M
S U P P L Y
TO V A C U U M BRAKE
R E L E A S E V A L V E
1— SERVO
2 — V A C U U M S O L E N O I D AND
V A L V E (NORMALLY C L O S E D )
3 — COIL
4 — VARIABLE I N D U C T A N C E
POSITION S E N S O R
5 — V E N T S O L E N O I D AND V A L V E
(NORMALLY OPEN)
6 — S T E E L C O R E
7 — THROTTLE A T T A C H M E N T
520163-9
Fig. 3 Servo Unit