EMISSION CONTROLS AND FUEL SYSTEM 139
H O T ( I
LIGHT
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IGNITION SWITCH
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TIME-DELAY
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TRANSMISSION SWITCH
(CLOSED IN LOW GEARS)
APPROX. (15 SEC.)
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1971 TCS system schematic
1971
The 1971 system is similar, except that the
vacuum solenoid (now called a Combination
Emissions Control solenoid) serves two func-
tions. One function is to control distributor
vacuum; the added function is to act as a de-
celeration throttle stop in high gear. This cuts
down on emissions when the vehicle is com-
ing to a stop in high gear. The CEC solenoid
is controlled by a temperature switch, a
transmission switch, and a 20 second time
delay relay. This system also contain^ a re-
versing relay, which energizes the solenoid
when the transmission switch, temperature
switch or time delay completes the CEC cir-
cuit to ground. This system is directly oppo-
site the 1970 system in operation. The 1970
vacuum solenoid was normally open to allow
vacuum advance and when energized, closed
to block vacuum. The 1971 system is nor-
mally closed blocking vacuum advance and
when energized, opens to allow vacuum ad-
vance. The temperature switch completes the
CEC circuit to ground when engine temper-
ature is below 82°. Corvettes also have a high
temperature terminal on the switch to com-
IDLE POSITION,
CLEAN AIR FILTER •
HIGH GEAR
DECELERATION
POSITION
TH^OTTLE
E
LEV
R
ER IDLE
MANIFOLD
VACUUM
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COLD I I
WATER
TEMP.
SWITCH
