Hummer H2. Manual — part 245

Fig. 4: Defogger Grid Line Zones
Courtesy of GENERAL MOTORS CORP.

4. Move the test lamp probe from zone 5 to zone 1 along each grid line.

z

If the test lamp shows full brilliance at both ends of the grid lines. Inspect for an open or poor
connection in the ground circuit of the rear window defogger grid. Refer to Testing for
Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

IMPORTANT: The test lamp brilliance will decrease proportionately to the increased

resistance in the grid line as the probe is moved from the battery positive
bus wire to the ground bus wire. The test lamp brilliance may vary from
one window to another.

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Stationary Windows - Hummer H2

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

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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