6 T - 1 2 E M I S S I O N C O N T R O L S Y S T E M S
Transmission Switch
On manual shift synchromesh transmissions, both 3-and
4-speed, the switch is located on the outside of the
transmission case in an area adjacent to the 2-3 or 3-4
shifter shaft, as applicable (fig. 7d). The mechanically
operated switch is spring loaded to provide continuity
between the switch terminal and the switch housing
When installed in the transmission, the plunger contacts
the shifter shaft, which causes the plunger to retract in
low forward gears, thereby opening the circuit to ground.
When the transmission is shifted into high forward gear,
the plunger drops into a recess or flat on the shifter
shaft, causing the plunger to rest internally on the switch
housing. A circuit is completed to ground, from the
transmission through the switch housing to the cup
contact and through the spring to the electrical terminal.
The Turbo Hydra-matic 350 transmission uses a pressure
sensitive switch, which is activated by transmission fluid
pressure. The Turbo Hydra-matic 350 switch (fig.
8
d) is
located externally in the 2-3 direct clutch pressure tap. At
rest, in or out of the installed position, the switch is in a
normally open position (fig. 9d). Construction of the
switch is such that a spring loaded diaphragm that
contains a metallic contact, is held away from a cup
contact, which in turn, is in contact with the switch
housing. Transmission fluid pressure, against the
insulated plug, forces the diaphragm upward so that the
diaphragm contact closes the circuit through the spring
to the electrical terminal.
EIGHT-CYLINDER ENGINES
The Transmission Controlled Spark System is used on all
10 Series vehicles, C-K20 suburban, G20 Series and G30
passenger vans when equipped with manual transmission. In
addition, the above vehicles also use the TCS system
when equipped with 307 cu. in. engine and automatic
transmission.
DESCRIPTION
Fig. 8d—Turbo Hydra-Matic 350 Transmission Switch
Location
Fig. 9d—Turbo Hydra-Matic 350 Transmission Switch
(Sectional View)
vacuum advance when the vehicle is operating in low
forward gears.
Vacuum advance is controlled by a solenoid-operated
switch, which is energized by grounding a normally open
switch at the transmission. When the solenoid is in the
non-energized position, vacuum to the distributor
advance unit is denied and the distributor is vented to
atmosphere through a filter at the opposite end of the
solenoid — venting the distributor advance unit prevents
it from becoming locked at an advanced position. When
the solenoid is energized, the vacuum port is uncovered
and the plunger is seated at the opposite end, shutting off
the clean air vent.
The vacuum advance solenoid is controlled by two
switches and a time relay. The solenoid is energized in
the high forward gear (and in reverse on Hydra-matic)
by a transmission operated switch. A thermostatic
coolant temperature switch is used to provide thermal
override below 93°F.
Wider throttle blade openings at idle are required to
compensate for the retarded spark condition produced
by the design of the emission reduction system. To
prevent engine dieseling at engine shut down, an idle
stop solenoid is provided. The ignition switch activated
idle stop solenoid eliminates dieseling tendencies by
allowing the throttle valve to close beyond the normal
idle position when the ignition is turned off.
SYSTEM THEORY
The system components are shown in their normal at rest
position with the engine off and cold (fig. le). The
temperature switch points are closed, making contact
Control of exhaust emitted by vehicles using the eight-
cylinder engines, is accomplished by eliminating ignition
LIGHT DUTY TRUCK SERVICE MANUAL
Summary of Contents for Light Duty Truck 1973
Page 1: ......
Page 4: ......
Page 6: ......
Page 53: ...HEATER AND AIR CONDITIONING 1A 27 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 115: ...LIGHT DUTY TRUCK SERVICE M A N U A L HEATER AND AIR CONDITIONING 1A 89...
Page 123: ...BODY 1B 3 Fig 6 Typical 06 Van LIGHT DUTY TRUCK SERVICE MANUAL...
Page 149: ...BODY 1B 29 Fig 84 Body Mounting 06 Fig 85 Body Mounting 14 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 171: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 2 Frame Horizontal Checking Typical FRAME 2 3...
Page 173: ...LIGHT DUTY TRUCK SERVICE M A N U A L Fig 4 10 30 Series Truck Frame FRAME 2 5...
Page 174: ...2 6 FRAME LIGHT DUTY TRUCK SERVICE MANUAL Fig 5 Underbody Reference Points G Van...
Page 185: ...FRONT SUSPENSION 3 11 Fig 16 Toe out on Turns LIGHT DUTY TRUCK SERVICE MANUAL...
Page 224: ......
Page 266: ......
Page 351: ...ENGINE 6 15 Fig ID Sectional View of Eight Cylinder Engine LIGHT DUTY TRUCK SERVICE MANUAL...
Page 375: ...EN G IN E 6 39 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 376: ...6 4 0 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Page 377: ...ENG IN E 6 41 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 378: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 37L K Series Engine Front Mount 6 42 ENG INE...
Page 400: ...6 6 4 ENG INE LIGHT DUTY TRUCK SERVICE MANUAL...
Page 401: ...ENG IN E 6 65 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 402: ...6 6 6 ENGINE LIGHT DUTY TRUCK SERVICE MANUAL...
Page 403: ...E NG IN E 6 67 Fig 36V C Series Engine Mounts LIGHT DUTY TRUCK SERVICE MANUAL...
Page 410: ......
Page 423: ...EN G IN E C OOLING 6K 13 Fig 16 Overheating Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Page 424: ...6 K 1 4 ENG INE COOLING Fig 17 Coolant Loss Chart LIGHT DUTY TRUCK SERVICE MANUAL...
Page 456: ...6M 32 ENGINE FUEL Fig K15 Accelerator Controls G Van L 6 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 492: ......
Page 512: ...Fig 18e Vacuum Advance Diagram V8 Engine...
Page 516: ...6 T 2 4 E M IS S IO N CONTROL SYSTEMS LIGHT DUTY TRUCK SERVICE MANUAL...
Page 528: ......
Page 590: ......
Page 593: ...CLUTCHES MANUAL TRANSMISSIONS 7M 3 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 598: ...7M 8 CLUTCHES MANUAL TRANSMISSIONS LIGHT DUTY TRUCK SERVICE MANUAL...
Page 642: ......
Page 654: ......
Page 743: ...FUEL TANKS AND EXHAUST 8 13 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 744: ...8 14 FUEL TANKS AND EXHAUST LIGHT DUTY TRUCK SERVICE MANUAL...
Page 760: ...8 30 FUEL TANKS AND EXHAUST Fig 40 Exhaust Pipe P Models LIGHT DUTY TRUCK SERVICE MANUAL...
Page 761: ...FUEL TANKS AND EXHAUST 8 31 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 763: ...FUEL TANKS AND EXHAUST 8 33 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 766: ......
Page 832: ...LIGHT DUTY TRUCK SERVICE MANUAL Fig 106 Power Steering Pump Mounting Typical 9 66 STEERING...
Page 833: ...PUMP ASSEMBLY STEERING GEAR TYPICAL SMALL V8 TYPICAL LARGE V8 STEERING 9 67...
Page 861: ...STEERING 9 95 Fig 134 Power Steering Pump Leakage LIGHT DUTY TRUCK SERVICE MANUAL...
Page 864: ......
Page 876: ......
Page 886: ...11 10 CHASSIS SHEET METAL LIGHT DUTY TRUCK SERVICE MANUAL...
Page 891: ...ELECTRICAL BODY AND CHASSIS 12 5 LIGHT DUTY TRUCK SERVICE MANUAL...
Page 934: ......
Page 942: ......
Page 970: ......
Page 972: ......
Page 974: ......
Page 976: ...V...
Page 978: ......
Page 979: ......