GM Service Manual Online
For 1990-2009 cars only

Step

Action

Value(s)

Yes

No

Schematic Reference: Defogger Schematics

Connector End View Reference: Component Connector End Views

1

Did you review the operation of the automatic day-night feature of the mirrors and perform the necessary inspections?

--

Go to Step 2

Go to Symptoms - Mirrors

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 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 or NEUTRAL.
  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 Step 11

6

  1. Place the transmission in REVERSE.
  2. 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 short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find and correct the condition?

--

Go to Step 13

Go to Step 11

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 13

Go to Step 12

9

Repair an open or high resistance on the ground circuit of the inside rearview mirror. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 13

--

10

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

Did you complete the repair?

--

Go to Step 13

--

11

Repair a short to voltage on the reverse lamp circuit of the inside rearview mirror. Refer to Wiring Repairs .

Did you complete the repair?

--

Go to Step 13

--

12

Replace the inside rearview mirror. Refer to Inside Rearview Mirror Replacement .

Did you complete the replacement?

--

Go to Step 13

--

13

Operate the system in order to verify the repair.

Did you correct the condition?

--

System OK

Go to Step 2