Chevrolet CHEVY VAN G10 SERIES Service Manual page 196

EMISSION C O N TR O L SYSTEM 6T-4
Fig. 6 T -8 —Manual Transmission Switch (Sectional V iew )
minal and the sw itch housing (Fig.
the plunger are non-conductors and therefore insulate the cup
contact and sw itch term inal when th e plunger is depressed.
When installed in the transm ission, the plunger co ntacts the
shifter shaft, which causes the plunger to retract in low
forw ard gears. When the transm ission is shifted into high
forw ard gear, the plunger drops in to a recess or flat on the
shifter shaft, causing the plunger to rest on the sw itch housing.
A circuit is com pleted to ground, from the transm ission
through the switch housing to the cup contact and through the
spring to the electrical term inal.
The Powerglide transm ission
sw itch, w hich is activated by transm ission fluid pressure. The
Powerglide switch (Fig. 6T-9) is located externally in a boss
adjacent to the low servo and activated by high clutch
pressure. A t rest, in or o ut o f the installed position, the sw itch
is in a norm ally open position (Fig. 6T-10). C onstruction of
the sw itch is such th a t a spring loaded diaphragm th a t contains
a m etallic co n tact, is held aw ay from a cup con tact, w hich in
6 8
T- ). The m olded top and
uses a pressure sensitive
Fig. 6 T -9 —Powerglide Transmission Switch Location
Fig. 6 T -1 0 —Powerglide Transmission Switch (Sectional V iew )
tu rn , is in co n tact w ith the sw itch housing. Transm ission fluid
pressure, against the insulated plug, forces the diaphragm
upw ard so th at the diaphragm contact closes the circuit
through the spring to the electrical term inal.
C H E V Y V A N S H O P M A N U A L