Hummer H2. Manual - part 715

Fig. 5: Testing Locations On Grid Lines 
Courtesy of GENERAL MOTORS CORP. 

z

If the test lamp goes out, test the grid line in at least 2 places (1,3) to eliminate the possibility of 
bridging the open (2) in the grid line.  

MIRRORS - AUTOMATIC DAY-NIGHT INOPERATIVE 

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 mirrors 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 OFF the automatic day-night feature of 

the inside rearview mirror.  

3. Observe the driver outside rearview mirror.  

Does the driver outside rearview mirror remain in a 
darken state?

-

Go to Step 20

Go to Step 3

1. Turn ON the automatic day-night feature of 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Stationary Windows - Hummer H2

  

3

the inside rearview mirror.  

2. Cover the sensor on the inside rearview mirror 

back, facing the front window.  

3. 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 Step 4

Go to Step 5

4

While shining a bright light into the sensor on the 
mirror face, facing the rear window, observe the 
driver outside rearview mirror. 
Does the driver outside rearview mirror darken?

-

Go to Testing for 

Intermittent 

Conditions and 

Poor Connections 

in Wiring Systems

Go to Step 9

5

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 ohm

Go to Step 6

Go to Step 18

6

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 7

Go to Step 19

7

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 8

Go to Backup 

Lamps Always 

On in Lighting 

Systems

8

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 15

Go to Step 12

1. Turn OFF the ignition.  

2. Disconnect the harness connector C2 of the 

driver door module (DDM).  

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Stationary Windows - Hummer H2

  

9

3. Turn ON the ignition, with the engine OFF.  

4. Turn ON the automatic day-night feature of 

the inside rearview mirror.  

5. Cover the sensor on the mirror back, facing the 

front window.  

6. Shine a bright light into the sensor on the 

mirror face, facing the rear window.  

7. Measure the voltage between the automatic 

day-night signal circuit and the low reference 
circuit of the driver outside mirror element.  

Is the voltage within the specified range?

0.75-

1.5 V

Go to Step 11

Go to Step 10

10

Measure the voltage between the automatic day-
night signal circuit of the driver outside mirror 
element and a good ground. 
Is the voltage within the specified range?

0.75-

1.5 V

Go to Step 14

Go to Step 13

11

1. Turn OFF the ignition.  

2. Disconnect the harness connector C3 of the 

DDM.  

3. Connect a 3-ampere fused jumper wire 

between harness connectors C2 and C3 for the 
automatic day-night signal circuit of driver 
outside rearview mirror element.  

4. Connect a 3-ampere fused jumper wire 

between harness connectors C2 and C3 for the 
low reference circuit of driver outside rearview 
mirror element.  

5. Turn ON the ignition, with the engine OFF.  

6. Turn ON the automatic day-night feature of 

the inside rearview mirror.  

7. Cover the sensor on the mirror back, facing the 

front window.  

8. Shine a bright light into the sensor on the 

mirror face, facing the rear window.  

9. While shining a bright light into the sensor on 

the mirror face, facing the rear window, 
observe the driver outside rearview mirror.  

Does the driver outside rearview mirror darken?

-

Go to Step 16

Go to Step 17

12

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 in Wiring Systems. 

-

Go to Backup 

Lamps 

Inoperative in 

Lighting 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Stationary Windows - Hummer H2

  

Did you find and correct the condition?

Go to Step 24

Systems

13

Test the automatic day-night signal circuit of the 
driver outside rearview mirror element for an open or 
short to ground. Refer to Circuit Testing and 
Wiring Repairs in Wiring Systems. 
Did you find or correct the condition?

-

Go to Step 24

Go to Step 15

14

Test the low reference circuit of the driver outside 
rearview mirror element for an open or high 
resistance. Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems. 
Did you find or correct the condition?

-

Go to Step 24

Go to Step 15

15

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 24

Go to Step 21

16

Inspect for poor connections at the harness connector 
of the DDM. Refer to Testing for Intermittent 
Conditions and Poor Connections and Connector 
Repairs in Wiring Systems. 
Did you find or correct the condition?

-

Go to Step 24

Go to Step 22

17

Inspect for poor connections at the harness connector 
of the driver outside rearview mirror. Refer to 
Testing for Intermittent Conditions and Poor 
Connections and Connector Repairs in Wiring 
Systems. 
Did you find or correct the condition?

-

Go to Step 24

Go to Step 23

18

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 24

-

19

Repair an open or 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 24

-

1. Repair a short to voltage on the automatic day-

night signal circuit of the driver outside 

IMPORTANT:

A short to voltage on the automatic day-night 
signal circuit of the driver outside rearview mirror 
element will cause permanent damage to the 
driver outside rearview mirror and the inside 
rearview mirror. Both mirrors will have to 
replaced. The following actions will need to be 
performed:

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Stationary Windows - Hummer H2