Pontiac Fiero 1988 Service Manual page 1256

CRUISE CONTROL 9B-1
SECTION 9 B
CRUISE CONTROL
CONTENTS
G e n e r a ! D e s c r i p t i o n
. . . . 9B-1
Off/On/Resume/Accel Switch
Operation 9B-1
Set/Coast Button Switch 9B-2
Electronic Controller (Module) 9B-2
Servo Unit 9B-2
Speed Sensors 9B-3
VSS/Buffer Amplifier 9B-3
PM Generator 9B-3
Vacuum Supply 9B-3
Electrical and Vacuum Release
Switches 9B-4
Electrical Harness 9B-4
Diagnosis
9B-4
Cruise System Surges 9B-4
Cruise Set Speed High or Low 9B-4
Excessive Cruise Speed Loss on Hills 9B-4
Cruise Tap-Up and Tap-Down 9B-4
On-Car Serwice (illustrated)
9B-5
Cruise Servo/Cable - V6 9B-5
Cruise Servo/Cable - L4 9B-6
Vacuum Tank/Servo/Hoses 9B-7
Cruise Control Module - V6 9B-7
Cruise Release Switches 9B-8
Cruise Wiring-V6. 9B-8
G E N E R A L D E S C R I P T I O N
Cruise control is a speed control system which
maintains a desired car speed under normal driving
conditions. However, steep grades up or down may
cause variations in the selected speeds. The electronic
cruise control system has the capability to cruise, coast,
resume speed, accelerate, and "tap-up" and
"tap-down".
The main parts of the cruise control system are
the mode control switches, controller (module), servo
unit, speed sensor, vacuum supply, electrical and
vacuum release switches, and electrical harness.
The cruise control system uses vacuum to operate
a throttle servo unit. The servo unit maintains a desired
car speed by trapping vacuum in the servo unit at the
proper servo position. The controller monitors vehicle
speed and servo position and operates the vacuum and
vent valves in the servo to maintain desired speed. The
controller contains a low speed limit which will prevent
system engagement below a minimum speed of about
25 mph. The operation of the controller is controlled
by mode control switches located in the end of the
directional signal lever. To disengage the system, two
release switches are provided. An electrical release
switch mounted on the brake pedal bracket (brake and
clutch pedal bracket on cars equipped with manual
transmission) disengages the system electrically when
the brake pedal (or clutch pedal) is depressed. A
vacuum release valve, mounted on the brake pedal
bracket, vents the trapped vacuum in the servo to
atmosphere when the brake pedal is depressed,
allowing the servo unit to quickly return the throttle
to idle position.
O F F / O N / R E S U M E / A C C E L SWITCH
(OPERATION)
Figure I
The Off/On/Resume/Accel Switch has three
positions. This switch turns the cruise control system
ON and OFF and also returns cruise control operation
to the last speed setting when MOMENTARILY
moved towards the R/A position after braking. (Do
not hold the slider in the R / A position ... release it
immediately.) If the slider is held in the R/A position
for more than one second, the system goes into the
Accel mode. To accelerate the car, move the slider
switch to the R/A position and hold it there until the
car reaches the desired speed. When the slider switch
is released, the system will maintain the new cruise
speed. In order to use the Accel mode, the cruise
OFF/ON/Resume/Accel switch must be in the "ON"
position and the car must be above the low speed limit
of 25 mph.
The slide switch can also be used to "tap-up" car
speed. In order to do this the cruise must be engaged
and operating. "Tapping-up" is done by quickly
pressing the slide switch toward the R/A position and
quickly releasing it, or "tapping" the lever. Do not hold
the lever in the R/A position or the system will go into
the Accel mode. "Tap-up" is a function in which cruise
speed can be increased by 1 mph increments (one tap
= 1 mph increase).
1 — D I R E C T I O N A L SIGNAL LEVER
2 — O F F / O N / R E S U M E / A C C E L SWITCH
3 — S E T / C O A S T S W I T C H
5 2 0 1 6 1 - 9
Fig. 1 Multi-Function Lever