GMC 4000 Series Service Manual page 538

3. P ress in on the assembly and rotate slightly
to engage horizontal and vertical adjusting screws
in slot in headlamp mounting ring.
4. Using the hooked tool, pull outward on re­
taining ring spring and engage in slot in retaining
ring as shown in View "B."
5. Check headlight adjustment as explained
under "Headlight Beam Adjustment" previously.
SINGLE SEALED-BEAM
UNIT REPLACEMENT
Removal (Fig. 13)
1. Remove screw s which attach headlamp bezel
to mounting ring, then remove the bezel.
2. Remove two screw s which attach headlamp
retaining ring to mounting ring. Using a hooked
tool, release retaining spring from slot in retain­
ing ring (inset, fig. 13). Swing bottom of retaining
ring out and disengage from retaining clip near top.
3. Remove sealed-beam unit from mounting
ring and pull wiring connector plug off back of unit.
Installation (Fig. 13)
1. Push wiring connector plug over blade-type
terminals on back of sealed-beam unit.
2. Position sealed-beam unit in mounting ring
with molded lugs on back of sealed-beam unit en­
gaged in locating holes in mounting ring.
3. Hook slot in retaining ring over retaining
clip near top of mounting ring and position retain­
ing ring over sealed-beam unit.
4. Using a hooked tool, pull out on retaining
spring and engage in slot near bottom of retaining
ring (Inset, fig. 13).
5. Adjust headlight beam as previously recom ­
mended under "Headlight Beam Adjustment."
6. Position headlamp bezel over mounting
ring and attach with screw s.
PARKING LIGHTS
Parking lights (when used) are illuminated
with main light switch pulled out to first detent
position. The parking light circuit is protected by
a fuse located in the main fuse block.
BULB REPLACEMENT
Removal
On conventional cab, cowl, and "S" models,
raise hood and pull bulb and socket assembly from
lamp assembly mounted in grille panel. P ress in­
ward on bulb and turn counterclockwise to remove
from socket.
On tilt cab models, remove two screws which
attach parking lamp lens to light assembly and re­
move lens. P ress bulb inward and turn counter­
clockwise to remove from socket.
G M C S E R V I C E M A N U A L
CHASSIS ELECTRICAL AND INSTRUMENTS
Retaining
Horizontal]
I Adjusting
Installation
this section for bulb size and type.
install new bulb in socket and insert socket and
bulb in lamp assembly. On tilt cab models, install
new bulb in socket, then attach lens and gasket to
lamp assembly with two screw s.
LAMP ASSEMBLY REPLACEMENT
tional cab, cowl, and "S" models, remove bulb and
socket assembly, then remove two screw s which
attach lamp assembly to front grille panel. Pull
lamp assembly from opening in grille panel.
tach lamp assembly to front end sheet metal. Pull
lamp assembly from opening and disconnect harness
at junction.
assembly in opening and install two attaching nuts.
Insert bulb and socket in lamp assembly or connect
harness at junction.
ing arrangements are used. Typical rear direc­
tional signal lights are integral part of stop and
taillight assembly. Back-up light assembly is lo­
cated beside or above taillight assem bly. Rear
lamp bulbs may be replaced by removing lens at­
taching screw s and lens. The lamp housing may be
replaced by removing the housing attaching nuts
or screw s, or by removing nuts and bolts from the
mounting bracket.
this section for bulb size and type.
Ring
Screw
Figure 13— Single Sealed Beam Unit Replacement
NOTE: Refer to "Light Bulb Data" at end of
On conventional cab, cowl, and "S" models,
To remove parking lamp assembly on conven­
On tilt cab models, remove two nuts which at­
To install a new lamp assembly, position the
REAR LIGHTING
Due to numerous models, various rear light­
NOTE: Refer to "Light Bulb Data" at end of
Sec. 12
Page 527
! Vertical |
Adjusting
Screw
Retaining
Spring