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Hummer H2. Manual - part 244

SYMPTOMS - STATIONARY WINDOWS

1. Perform the Diagnostic System Check - Defogger before using the symptom tables in order to verify

that all of the following are true:

There are no DTCs set.

The control modules can communicate via the serial data link.

2. Review the system operation in order to familiarize yourself with the system functions. Refer to Rear

Window Defogger Description and Operation .

Visual/Physical Inspection

Inspect for aftermarket devices which could affect the operation of the rear window defogger or the

Inspect for poor connections at the harness
connector of the BCM. 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 13

Go to Step 12

Repair an open or high resistance in ignition voltage
circuit of the DEFOG relay coil. Refer to Wiring
Repairs in Wiring Systems.
Did you complete the repair?

Go to Step 13

Replace the DEFOG relay.
Did you complete the replacement?

Go to Step 13

Replace the BCM. Refer to Body Control Module
Replacement in Body Control System.Did you
complete the replacement?

IMPORTANT:

Perform the set up procedure for the Body
Control Module (BCM). Refer to Body Control
Module (BCM) Programming/RPO Configuration
in Body Control System.

Go to Step 13

1. Use the scan tool in order to clear the DTCs.

2. Operate the vehicle within the Conditions for

Setting the DTC as specified in the supporting
text.

Does the DTC reset?

Go to Step 2

System OK

IMPORTANT: For the inside rearview mirror with the automatic day-night feature, review the

system operation in order to familiarize yourself with the system functions.
Refer to Automatic Day-Night Mirror Description and Operation .
For the rear window defogger system, the following steps must be performed
before using the symptom tables:

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Stationary Windows - Hummer H2

automatic day-night feature of the inside rearview mirror. Refer to Checking Aftermarket Accessories
in Wiring Systems.

Inspect the easily accessible or visible system components for obvious damage or conditions which could
cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for
Intermittent Conditions and Poor Connections in Wiring Systems.

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom:

Defogger Inoperative - Rear Window

Defogger Grid Lines Diagnosis

Mirrors - Automatic Day-Night Inoperative

Mirrors - Temperature Displays SC or OC

Mirrors - Compass Display Inoperative or Inaccurate

Mirrors - Temperature Display Inaccurate

DEFOGGER INOPERATIVE - REAR WINDOW

Defogger Inoperative - Rear Window

Step

Action

Yes

Schematic Reference:Defogger Schematics
Connector End View Reference:Stationary Windows Connector End Views

Did you perform the Defogger Diagnostic System
Check?

Go to Step 2

Go to Diagnostic

System Check -

Defogger

1. Start the engine.

2. Depress the rear window defogger switch.

3. Observe the rear window defogger indicator

on the HVAC Control Module.

Does the rear window defogger indicator illuminate?

Go to Step 3

Go to Step 8

Connect a test lamp between the left side of the rear
window defogger grid and a good ground.
Does the test lamp illuminate?

Go to Step 4

Go to Step 5

Connect a test lamp between the left side of the rear
window defogger grid and the right side of the rear
window defogger grid.
Does the test lamp illuminate?

Go to Testing for

Intermittent Conditions

and Poor Connections in

Wiring Systems

Go to Step 10

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Stationary Windows - Hummer H2

1. Turn OFF the ignition.

2. Disconnect the DEFOG relay.

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

4. Connect a test lamp between the battery

positive voltage circuit of the DEFOG relay
switched input and a good ground.

Does the test lamp illuminate?

Go to Step 6

Go to Step 7

1. Connect a 40 amp fused jumper between the

battery voltage circuit of the DEFOG relay
switched input and the relay switched output
to the supply voltage circuit of the rear
window defogger.

2. Connect a test lamp between the left side of

the rear window defogger grid and a good
ground.

Does the test lamp illuminate?

Go to Step 9

Go to Step 12

Test the battery positive voltage circuit of the
DEFOG relay switched input 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 15

Go to Step 11

Inspect for poor connection at the harness connector
of the HVAC Control Module. 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 15

Go to Step 13

Inspect for poor connection at the DEFOG relay.
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 15

Go to Step 14

Repair an open or high resistance in the ground
circuit of the rear window defogger. Refer to
Wiring Repairs in Wiring Systems.
Did you complete the repair?

Go to Step 15

Repair a short to ground in the supply voltage circuit
of the rear window defogger. Refer to Wiring
Repairs in Wiring Systems.
Did you complete the repair?

Go to Step 15

Repair an open or high resistance in the supply
circuit of the rear window defogger. Refer to
Wiring Repairs in Wiring Systems.

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Stationary Windows - Hummer H2

DEFOGGER GRID LINES DIAGNOSIS

This test is for reference only. A grid line fault requires the rear window replacement. Refer to Rear Lift
Window Replacement .

1. Start the engine.

2. Activate the rear window defogger system.

3. Connect a test lamp to a good ground.

Did you complete the repair?

Go to Step 15

Replace the HVAC Control Module. Refer to
HVAC Control Module Replacement in HVAC
Systems - Automatic.
Did you complete the replacement?

Go to Step 15

Replace the DEFOG relay.
Did you complete the replacement?

Go to Step 15

Operate the system in order to verify the repair.
Did you correct the condition?

System OK

Go to Step 2

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Stationary Windows - Hummer H2

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