GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2002 🢒 GMC C Sierra - 2WD 🢒 Body and Accessories 🢒 Stationary Windows 🢒 Automatic Day-Night Mirrors Inoperative

Diagnostic Aids

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.

Step

Action

Values

Yes

No

Schematic Reference: Inside Rearview Mirror Schematics

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. Turn ON the automatic day-night feature of the inside rearview mirror.
  3. Cover the sensor on the inside rearview mirror back, facing the front window.
  4. 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 ohms

Go to Step 4

Go to Step 9

4
  1. Turn ON the ignition, with the engine OFF.
  2. Measure the voltage between the ignition 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 10

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 8

Go to Step 7

7

Test the backup lamp supply voltage circuit of the inside rearview mirror for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Backup Lamps Inoperative in Lighting Systems

8

Inspect for poor connections at the harness connector of the inside rearview mirror. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 12

Go to Step 11

9

Repair an open or a 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

--

10

Repair an open or a short to ground in the ignition voltage circuit of the inside rearview mirror. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 12

--

11

Important: Perform Compass Calibration and Magnetic Variance for the inside rearview mirror.

Replace the inside rearview mirror. Refer to Inside 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