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Home >> Chevrolet >> 2002 >> Blazer 4D Utility, 4WD, Part Time >> Repair and Diagnosis >> External Pages >> Different car >> Section 1117 (Stationary Window System) >> Diagnostic Information and Procedures >> Mirrors - Automatic Day-Night Inoperative >> Diagnostic Aids

Diagnostic Aids

WARNING: This page is about a different car, the 2004 Pontiac Aztek and 2004 Buick Rendezvous. 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 voltage in the backup lighting system.

Mirrors - Automatic Day-Night Inoperative

Step Action Value(s) Yes No
Schematic Reference:  Inside Rearview Mirror Schematics  
Connector End View Reference:  Stationary Windows Connector End Views  
1 Did you review the operation of the automatic day-night feature of the inside rearview mirror and perform the necessary inspections? - Go to Step 2  Go to Symptoms - Stationary Windows 
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 forward side of the inside rearview mirror.
  5. Shine a bright light into the sensor on the rearward side of the inside rearview mirror.
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 10 
4
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage between the accessory voltage circuit and the ground circuit of the inside rearview mirror.
Is the voltage within the specified range?		 B+ Go to Step 5  Go to Step 7 
5
  1. Place the transmission in PARK.
  2. Measure the voltage between the backup lamp supply voltage circuit 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 in Lighting Systems
6
  1. Place the transmission in REVERSE.
  2. Measure the voltage between the backup lamp supply voltage circuit and the ground circuit of the inside rearview mirror.
Is the voltage within the specified range?		 B+ Go to Step 9  Go to Step 8 
7 Test the accessory voltage circuit of the inside rearview mirror for an open or short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Retained Accessory Power (RAP) Inoperative in Retained Accessory Power
8 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 in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Backup Lamps Inoperative in Lighting Systems
9 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 in Wiring Systems.
Did you find and correct the condition?		 - Go to Step 12  Go to Step 11 
10 Repair an open or high resistance in the ground circuit of the inside rearview mirror. Refer to Wiring Repairs in Wiring Systems.
Did you complete the repair?		 - Go to Step 12  -
11 Replace the inside rearview mirror. 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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