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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1810 (Mirror System) >> Diagnostic Information and Procedures >> Automatic Day-Night Mirrors Inoperative >> Diagnostic Aids

Diagnostic Aids

WARNING: This page is about a different car, the 2007 Saturn Vue. However, it is still accessible from the selected car via links, so may be relevant.

The automatic day-night feature of the inside rearview mirror may not operate properly or become inoperative due to an intermittent short to battery positive voltage in the backup lighting system.

Automatic Day-Night Mirrors Inoperative

Step Action Value(s) Yes No
Schematic Reference: Inside Rearview Mirror Schematics 
Connector End View Reference: Master Electrical Component List
1 Did you review the description and operation of the automatic inside day-night rearview mirror feature and perform the necessary inspections? - Go to Step 2  Go to Symptoms - Mirrors 
2
  1. Turn ON the ignition, with the engine OFF.
  2. Make sure the vehicle is not in Reverse.
  3. Turn ON the automatic day-night feature of the inside rearview mirror.
  4. Cover the sensor on the inside rearview mirror back, facing the front window.
  5. Shine a bright light into the sensor on the inside rearview mirror face, facing the rear window.
Does the inside rearview mirror darken?		 - Go to Diagnostic Aids Go to Step 3 
3
  1. Turn OFF the ignition.
  2. Disconnect the harness connector of the inside rearview mirror.
  3. Measure the resistance between the ground circuit of the inside rearview mirror and a good ground.
Is the resistance less than the specified value?		 3 Ω Go to Step 4  Go to Step 9 
4
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage between the accessory voltage circuit of the inside rearview mirror and the ground circuit of the inside rearview mirror.
Is the voltage within the specified range?		 B+ Go to Step 5  Go to Step 10 
5
  1. Place the transmission in PARK.
  2. Measure the voltage between the backup lamp supply voltage circuit of the inside rearview mirror and the ground circuit of the inside rearview mirror.
Is the voltage less than the specified value?		 0.5 V Go to Step 6  Go to Backup Lamps Always On
6
  1. Place the transmission in REVERSE.
  2. Measure the voltage between the backup lamp supply voltage circuit of the inside rearview mirror and the ground circuit of the inside rearview mirror.
Is the voltage within the specified range?		 B+ Go to Step 8  Go to Step 7 
7 Test the backup lamp supply voltage circuit of the inside rearview mirror for an open or high resistance. Refer to Circuit Testing and Wiring Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Backup Lamps Inoperative
8 Inspect for poor connections at the harness connector of the inside rearview mirror. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .
Did you find and correct the condition?		 - Go to Step 12  Go to Step 11 
9 Repair an open or high resistance in the ground circuit of the inside rearview mirror. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 12  -
10 Repair an open or short to ground in the accessory voltage circuit of the inside rearview mirror. Refer to Wiring Repairs .
Did you complete the repair?		 - Go to Step 12  -
11 Replace the inside rearview mirror. Refer to Control Module References for replacement, setup and programming. Refer to Rearview Mirror Replacement .
Did you complete the replacement?		 - Go to Step 12  -
12 Operate the system in order to verify the repair.
Did you correct the condition?		 - System OK Go to Step 2 
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