Pontiac FIREBIRD 1972 Service Manual page 1283

CHASSIS ELECTRICAL 12-13
ALL HEADLIGHTS INOPERATIVE OR INTERMITTENT
Loose connection
Check and secure connections at foot
switch and light switch.
Defective foot switch.
*Check voltage at foot switch with test
bulb. If bulb lights only at light blue wire
terminal, replace foot switch.
Open wiring
-
light switch to foot switch.
*Check voltage at light blue wire with test bulb.
If bulb lights at light switch light blue wire
terminal, but not at foot switch, repair open
wire.
Open wiring
-
light switch to battery. *Check voltage at light switch red wire terminal
with test bulb. If bulb fails to light, repair
open red wire circuit to battery (possible open
fusible link).
Circuit shorted to ground. *If, after a few minutes operation, headlights
flicker on and off and/or a thumping noise can
be heard from the light switch (circuit breaker
opening and closing), repair short to ground in
circuit between light switch and headlights.
After repairing short, check for headlight
flickering after one minute operation. If
flickering occurs, the circuit breaker has been
damaged and light switch must be replaced.
Defective light switch.
,
*Check voltage at light switch red and blue
wire terminals with test bulb. If bulb lights
at red wire terminal but not at light blue,
replace light switch.
UPPER OR LOWER BEAM WILL NOT LIGHT OR INTERMITTENT
Open connection or defective foot switch.
Circuit shorted to ground.
*See headlight circuit (Fig. 12- 17).
*Check voltage at foot switch headlight
terminals with test light. If bulb lights at
headlight terminals (blk/lt. green
-
upper beam,
blk/tan
-
low beam), repair open wiring between
foot switch and headlights. If bulb will not
light at one of the foot switch headlight
terminals, replace foot switch.
*Follow diagnosis shown above under "All
Headlights Inoperative or Intermittent".
CORNERING LAMPS DIAGNOSIS
ONE LAMP INOPERATIVE
CAUSE
Loose Connection
Bulb out.
Open ground connection.
Open wiring.
Defective directional signal switch.
CORRECTION
*Secure connector near lamp.
*Replace burned out bulb.
*If bulb is known good and test bulb lights at
connector near lamp, repair open ground connection.
*If test bulb lights on both sides of steering
column connector, repair open wiring between
connector and lamps. If not, check for open
connection in connector.
*If test bulb lights at brown wire terminals
of steering column connector but not at gray
(left turn) or black/white (Right turn) terminal,
replace directional signal switch.