Chevrolet 1977 light duty truck, Service Manual

Page: 840 / 861

T H E C R U I S E C O N T R O L E N G A G E S W I T C H
A S S E M B L I E S , B O T H T U R N S I G N A L &
I N S T R U M E N T P A N E L M O U N T E D T Y P E S ,
I N C O R P O R A T E T H R E E P O S I T I O N S W I T C H E S .
T H E S E P O S I T I O N S A R E :
( A ) T H E “ R E L E A S E D ” O R N O R M A L P O S I T I O N
( B) T H E " E N G A G E ” P O S I T I O N
( C) T H E “ T R I M - D O W N ” P O S I T I O N .
P A R T I A L L Y D E P R E S S I N G T H E E N G A G E S W I T C H
W I L L A C T I V A T E T H E S Y S T E M A N D I T W I L L
R E M A I N A C T I V I T E D W H E N T H E S W I T C H I S
R E L E A S E D . T H E C R U I S E S Y S T E M I S
D E A C T I V A T E D W H E N T H E B R A K E S A R E
A P P L I E D O R W H E N T H E E N G A G E S W I T C H I S
D E P R E S S E D F U L L Y A N D H E L D I N T H E
“ T R I M - D O W N ” P O S I T I O N .
T H E “ T R I M - D O W N ” S W I T C H P O S I T I O N I S
N O R M A L L Y U S E D T O D E C R E A S E T H E
C R U I S I N G S P E E D . W H I L E T H E S W I T C H I S H E L D
I N T H E “ T R I M - D O W N ” P O S I T I O N T H E C R U I S E
S Y S T E M I S “ O F F ” A N D T H E C A R S P E E D W I L L
G R A D U A L L Y D E C R E A S E . W H E N T H E D E S I R E D
C R U I S I N G S P E E D I S R E A C H E D , T H E S W I T C H I S
S L O W L Y R E L E A S E D A N D T H E C R U I S E S Y S T E M
W I L L R E - E N G A G E . I F T H E S W I T C H I S
R E L E A S E D F R O M T H E “ T R I M - D O W N ”
P O S I T I O N V E R Y R A P I D L Y , I T I S Q U I T E L I K E L Y
T H A T T H E S Y S T E M W I L L N O T R E - E N G A G E .
T H I S I S N O R M A L A N D I S A V O I D E D B Y A
S L O W E R , M O R E D E L I B E R A T E R E L E A S E O F
T H E S W I T C H F R O M T H E “ T R I M - D O W N ”
P O S I T I O N .
N O T E : A S P E E D S W I T C H B U I L T I N T O T H E
R E G U L A T O R A S S E M B L Y P R E V E N T S
E N G A G I N G T H E C R U I S E S Y S T E M B E L O W
A P P R O X . 3 0 M P H .
Fig. 9-lC -C ruise Master Engagement Switches
system re-engages at the lower speed w hen the button is
slowly released.
Cruise M a s te r Units
1. T he E n g ag em en t Switch, which is located at the
end o f the directional signal lever, is used to control the
system
a n d fo r u p w a rd an d do w n w ard speed
adjustm ents.
2. The Regulator (fig. 9-2C) is m ounted in the
sp eed o m eter cable line. It is a c om bination speed sensing
device an d control unit. W h e n engaged, it senses vehicle
speed and positions the Servo Unit to m ain tain the
selected speed.
3. The Servo U nit is m ounted on the left front
in n e r fen d er and is connected by a cable to the throttle
linkage. It opens or closes the throttle as dictated by the
Regulator.
4. The Cruise Brake Release Switch, which is
m ounted on the brake pedal bracket, disengages the
system electrically w hen the brake pedal is depressed.
5. The Cruise Brake Release Valve, which is
m ounted on the brake pedal bracket, disengages the
system pneum atically w hen the brake pedal is depressed. pig
9
.
2
c .
Regulator
Unit
6. The Cable and Casing Assemblies drive the
regulator and speedometer.
H O L D
T E R M I N A L
E N G A G E
T E R M I N A L
L O C K N U T
F R O M E N G I N E
V A C U U M
T O T E E -
I N P U T F R O M
T R A N S M I S S I O N
'' A I R F I L T E R
&
S O L E N O I D
H O U S I N G C O V E R
O U T P U T T O
S P E E D O M E T E R
J
O R I F I C E T U B E
&
C O N N E C T O R A S S E M B L Y