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Test B: Outside Automatic Day/Night Mirror Inoperative

NOTE: Reviewing system description and operation information will help determine if condition described by customer is normal operation, and may help determine correct symptom diagnostic procedure when a malfunction exists.
  1. If automatic day/night mirror system description and operation has been reviewed, go to next step. If description and operation has not been reviewed, see DESCRIPTION & OPERATION  .
  2. Turn on inside rearview mirror automatic day/night feature. Cover sensor on inside rearview mirror back (facing front window). Shine a bright light into sensor on inside rearview mirror face (facing rear window). If inside rearview mirror darkens, go to next step. If inside rearview mirror does not darken, go to TEST A: INSIDE AUTOMATIC DAY/NIGHT MIRROR INOPERATIVE  .
  3. While shining bright light into sensor on inside rearview mirror face (facing rear window), observe left outside rearview mirror. If left outside rearview mirror does not darken, go to next step. If left outside rearview mirror darkens, go to DIAGNOSING INTERMITTENTS  .
  4. Carefully remove left outside mirror face/glass. See LEFT OUTSIDE MIRROR FACE/GLASS  under REMOVAL & INSTALLATION. Turn ignition switch to OFF position. Disconnect left outside rearview mirror 8-pin harness connector. Turn ignition switch to RUN position. Turn on inside rearview mirror automatic day/night feature. Cover sensor on inside rearview mirror back (facing front window). Shine a bright light into sensor on inside rearview mirror face (facing rear window). Measure voltage between left outside rearview mirror 8-pin harness connector terminals "E" (Black wire) and "F" (Gray wire). See Fig 1 . If voltage is not 0.75-1.5 volts, go to next step. If voltage is 0.75-1.5 volts, go to step  6 .
  5. Measure voltage between ground and left outside rearview mirror 8-pin harness connector terminal "F" (Gray wire). If voltage is not 0.75-1.5 volts, go to step  7 . If voltage is 0.75-1.5 volts, go to step  8 .
  6. Turn ignition switch to OFF position. Reconnect left outside rearview mirror 8-pin harness connector. Turn ignition switch to RUN position. Turn on inside rearview mirror automatic day/night feature. Cover sensor on inside rearview mirror back (facing front window). Shine a bright light into sensor on inside rearview mirror face (facing rear window). Measure voltage (backprobe) between left outside rearview mirror 8-pin harness connector terminals "E" (Black wire) and "F" (Gray wire). If voltage is 0.75-1.5 volts, go to step  9 . If voltage is not 0.75-1.5 volts, go to step  10 .
  7. Test Gray wire between left outside rearview mirror and inside rearview mirror for an open or high resistance. See appropriate wiring diagram in ILLUMINATION/INTERIOR LIGHTS article. If an open or high resistance is not found, go to step  11 . If an open or high resistance is found, repair as necessary. After repair, go to step  15 .
  8. Test Black wire between left outside rearview mirror and ground point for an open or high resistance. Ground point is located inside left door sill, forward of front seat. If an open or high resistance is not found, go to step  11 . If an open or high resistance is found, repair as necessary. After repair go to step  15 .
  9. Check for poor connections at left outside rearview mirror connectors. If poor connections are not found, go to step  11 . If poor connections are found, repair as necessary. After repair, go to step  15 .
  10. Check for poor connections at left outside rearview mirror connectors. If poor connections are not found, go to step  12 . If poor connections are found, repair as necessary. After repair, go to step  15 .
  11. Check for poor connections at inside rearview mirror. If poor connections are not found, go to step  13 . If poor connections are found, repair as necessary. After repair, go to step  15 .
  12. Replace left outside rearview mirror face/glass. See LEFT OUTSIDE MIRROR FACE/GLASS  under REMOVAL & INSTALLATION. After repair, go to step  15 .
  13. Replace left outside rearview mirror. See LEFT OUTSIDE MIRROR ASSEMBLY  under REMOVAL & INSTALLATION. After repair, go to step  15 .
  14. Replace inside rearview mirror. See INSIDE REARVIEW MIRROR  under REMOVAL & INSTALLATION. After repair, go to next step.
  15. Operate system to verify repair. If system does not operate properly, go to step  2 . If system operates properly, system is okay.
Fig 1: Identifying Left Outside Rearview Mirror 8-Pin Harness Connector Terminals
G99H02286Courtesy of GENERAL MOTORS CORP.