Pontiac FIREBIRD 1972 Service Manual page 750

EMISSION CONTROL SYSTEMS 6D-7
Essential services included in the tune-up items are: equipped with 4 speed manual transmission, retain the
Transmission Controlled Spark Advance (T.C.S.).
1. Check ignition timing (distributor advance hose dis-
connected and plugged and idle stop solenoid inac-
The T.C.S. and S.C.S. systems are composed of a vacuum
tive). advance solenoid valve, a temperature sensor switch and
depending upon the system, either a T.C.S. transmission
2. Check engine idle speed.
switch or a S.C.S. speed control spark switch. The temper-
ature senser switch has been relocated from the top of the
3. Check operation of distributor T.C.S. or S.C.S. ad-
intake manifold to the rear of the right cylinder head
vance system.
between spark plugs 6 and 8.
The C.C.S. system has been redesigned to include a Con-
The normal operation of the T.C.S. or S.C.S. systems
trolled Spark System, which is used on all engines, on both
allow vacuum controlled spark advance to the distributor
manual and automatic transmissions (Fig. 6D- 11 and 6D-
in fourth gear ONLY (T.C.S.) or when the vehicle speed
12).
exceeds 38 m.p.h. (S.C.S.). There are two conditions
where vacuum controlled spark advance will be available
All six cylinder and 307 V-8 engines use the Combined
in all other modes of operation:
Emission Control System (C.E.C.). All other engines ex-
cept 4 speed manual transmission equipped V-8's use the
1. Cold engine operation
-
Engine temperature below
Speed Control Spark Advance (S.C.S.). All V-8's
95°F.
S.C.S. TRANSMISSION
CONNECTOR (S.C.S. ONLY)
T.C.S. TRANSMISSION
AUTOMATIC
CONNECTOR (T.C.S. O N L Y )
CONNECTOR
AUTO
TRANS
SOLENOID BLUE ONLY
ELK SGL ORN
DK GRN
TEMP. SW.
TO TEMP. LIGHT
I
ELK DBL PINK
DK
GRN TRANSMISSION CONTROLLED SPARK
DBL
EXHAUST EMISSION C O N T R O L
(T.C.S.
&
S.C.S.)
' %
TO FUSE
BLOCK (
+
12V.) DOWNSHIFT SWITCH
Fig. 6D-1 1 Controlled Spark Systems (S.C.S./T.C.S.)
-
Schematic