Chevrolet Light Duty Truck 1973, Service Manual

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E M I S S I O N C O N T R O L S Y S T E M S 6 T - 1 1
CEC SO LEN O ID
IDLE STOP SO LEN O ID
Fig. 5d—L-6 Idle Stop and CEC Solenoids
COMPONENT DESCRIPTION
Idle Stop Solenoid
The idle stop solenoid is a two position electrically
operated control, used to provide a predetermined
throttle setting (fig. 5d). In the energized position
(plunger extended) the plunger contacts the carburetor
throttle lever and prevents full closing of the carburetor
throttle plates. This fast idle control when de-energized
(plunger retracted) allows throttle plates to close beyond
the normal idle position; thereby shutting off air supply
and in essence starving the engine so that it will shut
down without dieseling. The idle stop solenoid is attached
to the carburetor so that the plunger, when extended,
contacts the throttle lever.
CEC SOLENOID
The CEC solenoid (fig. 5d) is a two-position electrically
operated control, which serves a dual function in the
TCS system. In the de-energized position the spring
loaded plunger closes the vacuum supply port to the
distributor advance unit and opens the air vent to the
advance unit. In the energized position the plunger is
extended to contact the carburetor throttle lever and to
open the vacuum port to the distributor and to shut off
the air vent. The solenoid is bracket-attached to the
carburetor so that the plunger, when extended, contacts
the throttle lever to maintain a predetermined throttle
opening.
Fig. 6d—L-6 Temperature Cold Override Switch
Time Relay
The time relay is an electrically operated on-off type
switch. When the coil is energized it begins to heat the
bi-metal strip to open the normally closed relay points in
approximately 20 seconds. A ground path is provided for
through the relay housing and mounting bracket. Two
self-tapping screws attach the relay to the upper portion
of the vertical wall of the cowl near the vehicle
centerline.
Temperature Cold Override Switch
The cold override switch, located in the thermostat
housing (fig.
6
d) serves to activate the CEC solenoid. At
coolant temperatures below 93 (± 7 ) degrees, the cold
terminal is contacted by the bi-metallic strip to ground
and completes the circuit to the CEC solenoid. In the
neutral position, no contact is made; therefore the circuit
is broken.
Fig. 7d—Transmission Switch Location (Manual)
LIGHT DUTY TRUCK SERVICE MANUAL
TCS TEMPERATURE SWITCH