Chevrolet 1977 light duty truck, Руководство по обслуживанию

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Fig. 3B-62--Steering Colum n Cover and Seal
Ignition Sw itch (C and K Series)
T h e ignition switch is m ounted on top of the column
jacket n e a r the fro n t o f the dash. F o r anti-theft reasons,
the switch is located inside the channel section o f the
brake pedal support and is completely inaccessible
w ithout first lowering the steering column (see steering
colum n removal).
T h e switch is actuated by a rod and rack assembly.
A portion o f the rack is toothed and engages a gear on
the end o f the lock cylinder, thus enabling the rod and
rack to be moved axially (with respect to the column) to
actuate the switch w hen the lock cylinder is rotated.
Removal
1. Lower the steering column as outlined und er
"S teerin g Colum n R em oval" later in this section. It is
not necessary to remove the steering wheel.
CAUTION:
I f the steering column is not
rem oved fr o m the vehicle , be sure that it is
properly supported, before proceeding.
2. The switch should be positioned in "L o ck "
position before removing. If the lock cylinder has
already been removed, the actuating rod to the switch
should be pulled up until there is a definite stop, then
moved down one detent, which is the "L o ck " position.
3. Remove the two switch dBrews and remove the
switch assembly.
Installation
1. Before replacing the switch, be sure that the lock
is in the " L o c k " position (fig. 3B-61); if it is not, a
screwdriver (placed in the locking rod slot) can be used
to move the switch to "Lock".
2. Install the activating rod into the switch and
assemble the switch on the column; tighten the m ounting
screws.
CAUTIO N: Use only the specified screws since
over-length screws could prevent a portion o f
the assembly fro m compressing under impact.
3. Reinstall the steering column assembly follow­
ing the " M a n d a to r y Installation Sequence" outlined later
in this section.
S teering Colum n
All models which are equipped with the Function
Locking Energy A bsorbing Steering Columns are one o f
five basic designs.
1. Synchromesh
- The synchromesh column is
used on models with the s tan d ard transmission and
column m ounted shift levers. The shift tube, within the
outer column jacket, includes two lower shift levers for
connection to the transmission control linkage. This
column does not lock the transmission when the lock
cylinder is in the "lock" position.
2. Floor Shift - This column is used on models
equipped with a m an u al transmission with the shift lever
on the floor. This column does not lock the transmission
w hen the lock cylinder is in the "lock" position.
3. Automatic Column Shift - This column has a
single lower shift lever for shifting the autom atic
transmission.
The transmission is locked in Park w hen the lock
cylinder is in "Lock".
4. Tilt Column Option automatic transmission -
T he upper end and steering shaft o f this column is
specifically designed to accom m odate the optional tilt
steering wheel. The lower portion o f the column is the
same as in item n u m b e r 3.
5.
Tilt Column Option Manual Transmission
- This
column is the same as the autom atic transmission tilt
column except in corporating provisions for the m anual
transm ission shifting and the transmission is not locked
when the lock cylinder is in "L o ck " position.
To perform service procedures on the steering
column upp er end components, it is not necessary to
remove the column from the vehicle.
T he steering wheel, horn components, directional
signal switch, and ignition lock cylinder m ay be removed
with the column r e m a in in g in the vehicle as described
earlier in this section.
CAUTION: The outer m ast ja c k e t shift tube,
steering shaft a n d instrum ent panel m ounting
bracket are designed as energy absorbing units.
Because o f the design o f these components, it is
absolutely necessary to handle the column with
care when perform ing any service operation.
A void ham m ering, jarring, dropping or leaning
on any portion o f the column. When reassem­
bling the column components, use only the
specified screws, nuts and bolts and tighten to
specified torque. Care should be exercised in
using over-length screws or bolts as they m ay
prevent a portion o f the colum n fr o m
compressing under impact.
Inspection
To determ ine if the energy absorbing steering
column com ponents are functioning as designed, or if
repairs are required, a close inspection should be made.