I put together a troubleshooting cheat sheet for diagnosing headlights on the first generation headlights for years 84 – 86. Please note that this assumes that your headlight switch is ok. This ought to be an invaluable aid for everyone as a reference chart to help my fellow Fiero friends with headlight difficulties. This should print out on a single page of paper too.
TWITCHING HEADLIGHT MOTORcrumpled bumpers
bumpers not under the cage
main gear is stripped
worm gear is stripped
main gear incorrectly attached to armature
rubber bushing under knob left out of motor during re-assembly
HEADLIGHT MOTOR WON’T SHUT OFFstripped main gear
stripped worm gear
crumpled bumper debris clogging gears
BOTH HEADLIGHTS WONT OPENbad ground or connection
blown main fuse link to headlight switch
bad isolation relay
BOTH HEADLIGHTS WONT CLOSEbad ground or connection
blown 20-amp taillight fuse
bad isolation relay
ONE HEADLIGHT WON’T OPENbad ground or connection
blown actuator relay fusible link
bad actuator relay
bad actuator motor limit switch
bad actuator motor
ONE HEADLIGHT WON’T CLOSEbad ground or connection
bad actuator relay
bad isolation relay
bad actuator motor limit switch
bad actuator motor
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jetman
Silver 86 SE 2M6 4-speed, with "check wallet light"
Now fortified with 8 essential slices of bacon goodness