GMC 1976 ZEO 6083 Maintenance Manual page 119

T
co
c
m
CD 2
n
.
d
m
3
v
d
.
0
td
With ign . swi
and heater o
one of the f
1 . From fuse panel to blower switch .
2. From blower switch to resistor .
3. From resistor to blower motor .
NOTE : Shor
mittent . If t
a short circu
around as mu
create short
for arcing .
LAMP ON
Replace blower
speed switch .
"Run" position
on, locate short in
ing wires : (see note)
it may be inter-
does not indicate
e heater harness
possible to re
Watch and listen
Check FEED wire from
resistor to blower
speed switch .
BLOWER MOTOR INOPERATIVE
(ANY SPEED)
Check for proper
fuse
POOR OR NO GROUND
Repair g ound
LAMP LIGHTS
Replace mote
LAMP LIGHTS
Repair open in
wire from blower
motor to blower
relay .
LAMP DOES NOT LIGHT
Use 12 volt test light and check
wire terminals at resistor .
ELECTRICAL SYSTEM DIAGNOSTIC CHART
FUSE OK
The following tests should be made
with the ignition switch in "Run"
position, heater or A/C on and
blower switch on high .
Check blower motor ground
Check motor connector with
12 volt test light .
LAMP DOES NOT LIGHT
Check wire connector on
blower relay with 12 volt test light .
LAMP DOES NOT LIGHT
Check wire connector on blower
relay with 12 volt test light .
LAMP LIGHTS
Replace resistor
Replace
TEST LIGHT DOES NOT
LIGHT ON ALL TERMINALS
Replace resistor
LAMP LIGHTS IN ALL POSITIONS
Connect 12 volt test light at wire
terminal on blower relay (wire
from resistor to blower relay) .
LAMP LIGHTS
blower relay . Repair open in wire
from resistor to
blower relay .
BLOWER MOTOR INOPERATIVE
(CERTAIN SPEEDS-EXCEPT HIGH)
Disconnect resistor connectors, connect one lead
of a self powered test light to any one terminal
and use the other lead to probe each of the
other terminals .
LAMP DOES NOT LIGHT
Replace blower speed
switch .
TEST LIGHT LIGHTS ON
ALL TERMINALS
With ignition switch in "Run" position and heater
or A/C on, use 12 vclt test lamp to check for
voltage at resistor connector with blower speed
switch in each position .
LAMP DOES NOT LIGHT IN ALL POSITIONS
Turn ignition key off and put Heater or A/C
Control in off position. With blower resistor wire
connector disconnected, connect a jumper lead
from battery positive terminal to the wire terminal
in connector .
Use 12 volt test light to check for
voltage at wire at blower speed switch connector .
Repeat same test on the other wires.
LAMP LIGHTS ON LAMP DOES NOT LIGHT
ALL WIRES
ON ALL WIRES
Repair open in
affected wire .
A-2318