Pontiac FIREBIRD 1972 Service Manual page 1287

CHASSIS ELECTRICAL 12-17
SlDE MARKER LAMPS DIAGNOSIS
ONE LAMP INOPERATIVE
CAUSE
Directional signal bulb out (front lamp)
Side marker bulb out.
Loose connection or open wiring
CORRECTION
*Turn on directional signal. If signal bulb does
not light, replace bulb. (Bulb filament provides
ground path for marker lamp bulb through light
blue or dark blue/white wires.)
Replace burned out bulb.
*Check voltage at bulb socket brown wire
terminal with test bulb. If bulb lights, repair
open ground circuit. If bulb does not light,
repair open brown wire circuit.
FRONT OR REAR LAMPS INOPERATIVE
Loose connection or open ground connection *If associated tail or park lamps do not operate,
secure all connectors in brown wire circuit.
If park and tail lamps operate, repair open
Multiple bulbs out. ground connections. Replace burned out bulbs.
ALL LAMPS INOPERATIVE
Fuse blown.
Loose connection.
Open wiring.
Defective light switch.
*See side marker circuit (Fig. 12-20).
*If park and tail lamps do not operate, replace
tail fuse if blown. If new fuse blows, check for
short to ground between fuse panel and lamps.
*Secure connector to light switch.
*Check voltage at tail fuse with test bulb. If
bulb lights, repair open wiring between fuse and
light switch. If not, repair open wiring between
and battery. (Possible open fusible link.)
*If test bulb lights at light switch
terminal
# 5
but not at terminal #4, replace
light switch.
TAIL, PARK OR LICENSE LAMPS DIAGNOSIS
ONE SlDE INOPERATIVE
CAUSE
Bulb out.
Open ground connection at bulb socket or
ground wire terminal.
CORRECTION
Replace
*Jumper bulb base socket connection to ground.
If lamp lights, repair open ground circuit.