Chassis Electrical And Instruments - Chevrolet HM80 Series Service Manual

Sec. 12-felO _________________________________

CHASSIS ELECTRICAL AND INSTRUMENTS

DK. QREEN (COIL)
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TRAILER MARKER
&"'*
*P RELAY
FEED CABLE
TRAILER CABLE INST. PANEL
AND PLUG WIRING HARNESS
Figui e 2 —Chassis Junctions (Conv. Cab) (Typical)
The
^nsulation on each w ire is distinctly color-
ed and ps
tterned to a s s is t in tracing and testing
c ircu its nd to a s s is t in making connections. Ab-
and sym bols used in w ire insulation
breviatioh
co lor and pattern designations on Wiring Diagram s
a re as foil ows:
BLK. . . .
Black
BRN. . . . Brown
CH. . . . Check
CR. . . . C ross
GRN. . . . Green
NAT. . . .; Natural
ENGINE IfARNESS-TO-INSTRUMENT
PANEL HARNESS CONNECTOR
NOTE): Information pertaining to the 32 -term ­
inal engine harness to instrum ent panel harness
connector used on S eries
rem ains the sam e as covered in CHASSIS ELEC­
TRICAL AND INSTRUMENTS (SEC. 12), pages 12-1
through 12-79 in the
S ervice M0pnaul ST135-70 except as follows:
Power supply to the engine and cab wiring
h a rn ess qn conventional cab m odels and S e r ie s
90 tilt caty m odels is made through a m ale-fem ale
type connector enclosed in rubber.
1 ~L
FUEL TANK
SELECTOR
SWITCH WIRING
LEFT FUEL TANK WIRE
B
r ig h t f u e l t a n k w ir e
ORG. . . Orange
PPL. . . Purple
TR.
. . T racer
YELL.
. . Y ellow
. . P a rallel
/ /
WHT. . . White
90 tilt cab m odels
1970 Heavy Duty Truck
CIRCUIT BREAKER
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CHASSIS JUN CTION BLOCK
Figure 3 —Chassis Junction Block (Tilt Cab M odels) (Typical)
It is recom m ended that this connector, as
w ell as sim ila r connectors in the wiring harness,
be cleaned and lubricated with a m ulti-purpose
g rea se whenever the connector is separated or
whenever difficulty caused by corrosion has been
encountered. The lubricant w ill keep m oisture off
the ele c tr ica l term in als and thus prevent corro­
sion which can cause high resista n ce in the sy stem .
On conventional cab m odels, the 32-term inal
connector is mounted on the upper right-hand side
of the dash panel in the engine compartment;
Term inal le tte r s shown on wiring connector body
(fig. 1) correspond to lette r s on w iring diagram s
and in the tabulation which follows: the tabulation
lis ts each term inal letter, the circuit it ca r r ie s,
and the siz e , color, and pattern of the w ire which
connects to each term inal.
Connector Replacem ent
NOTE: Wiring connector term inals should be
checked for proper alignm ent and to ensure that
they are properly seated in connector c a v ities.
1. Rem ove two screw s which attach the two-
p ost junction block to the dash panel; then rem ove
two screw s which attach the 32-term inal bulkhead
connector to the dash panel.
2. Insert a 7/1 6 -in ch socket through engine
h arness wiring, then turn retaining bolt out of con­
nector body. Separate engine harness connector
from instrum ent panel harness connector.
NOTE: The retaining bolt w ill rem ain in the
engine harness connector.
IMPORTANT: Mating connectors must be a s ­
sem bled straight and slow ly to a ssu re proper
alignm ent of term in als. Tighten bolt slow ly to ap­
proxim ately 60-inch-pounds torque. W hile bolt is
being tightened, check to be su re gap between con­
n ectors is uniform.
CHEVROLET SERIES 70-90 HEAVY DUTY TRUCK SHOP MANUAL SUPPLEMENT
-SPEED AXLE)
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T-8003