Hummer H2. Manual — part 1124

generator housing.

Does the green POWER lamp on the tester illuminate?

Go to

Step 6

Go to Step 4

4

Measure the voltage from the output terminal of the
generator to the generator metal housing.
Does the voltage measure equal to the specified value?

12.0 V

Go to

Step 14

Go to Step 5

5

Measure the voltage from the output terminal of the
generator to the battery negative terminal.
Does the voltage measure equal to the specified value?

12.0 V

Go to

Step 12

Go to Step 11

6

1. Turn OFF completely the load tool before connecting

or disconnecting a carbon pile load tester to the
battery. Otherwise, sparking at the terminals could
cause battery gasses to explode.

2. Connect a carbon pile tester to the vehicle.

3. Connect an inductive ammeter to the output circuit of

the generator.

4. Disconnect the generator harness connector.

5. Locate the matching harness connector on the J 41450-

B , and connect the connector to the generator.

Does the red DIAGNOSTIC lamp on the tester illuminate?

IMPORTANT:

Ensure that all generator output circuit wires pass
through the inductive probe.

-

Go to

Step 7

Go to Step 13

7

1. Start the engine and allow it to idle for 30 seconds.

2. Increase the engine speed to 2,500 RPM.

Does the red DIAGNOSTIC lamp on the tester illuminate?

-

Go to

Step 15

Go to Step 8

8

1. Maintain the engine speed at 2,500 RPM.

2. Turn ON the load of the carbon pile tester and increase

the load until the generator output is equal to the Load
Test value given in Generator Usage.

Does the red DIAGNOSTIC lamp on the tester illuminate?

IMPORTANT:

If the generator is not capable of producing the
Load Test amps, operate the generator at it's
maximum possible output.

-

Go to

Step 15

Go to Step 9

1. Maintain the engine speed at 2,500 RPM and continue

2004 Hummer H2

2004 ELECTRICAL Engine Electrical - Hummer H2

CHARGE INDICATOR ALWAYS ON

9

to operate the generator at the load test value.

2. Measure the voltage drop from the output terminal of

the generator to the positive terminal on the battery.
Refer to Circuit Testing and to Wiring Repairs in
Wiring Systems.

Does the voltage measure greater than the specified value?

0.5 V

Go to

Step 11

Go to Step 10

10

1. Maintain the engine speed at 2,500 RPM and continue

to operate the generator at the load test value.

2. Measure the voltage drop from the battery negative

terminal to the metal housing of the generator. Refer to
Circuit Testing and to Wiring Repairs in Wiring
Systems.

Does the voltage measure greater than the specified value?

0.5 V

Go to

Step 12

Go to Step 16

11

Repair the high resistance or an open in the output circuit of
the generator. Refer to Circuit Testing and to Wiring
Repairs in Wiring Systems.
Did you complete the repair?

-

Go to

Step 16

-

12

Repair the high resistance or open in the ground circuit of the
generator. Refer to Circuit Testing and to Wiring Repairs
in Wiring Systems.
Did you complete the repair?

-

Go to

Step 16

-

13

1. Disconnect the J 41450-B tester harness connector

from the generator, but leave the alligator clips
connected so that the green POWER lamp remains
illuminated.

2. Connect a jumper lead, with an in-line 100-ohm

resistor between the J 41450-B tester harness
connector terminal B of the generator and a good
ground. Refer to Engine Electrical Connector End
Views .

Does the red DIAGNOSTIC lamp illuminate?

-

Go to

Step 15

Go to Step 14

14

There is a problem with the J 41450-B . Refer to the
manufacturers instructions, how to test the J 41450-B for
proper operation.
Has the J 41450-B tester been replaced?

-

Go to

Step 3

-

15

Replace the generator. Refer to Generator Replacement .
Did you complete the replacement?

-

Go to

Step 16

-

16

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

-

System

OK

Go to Step 2

2004 Hummer H2

2004 ELECTRICAL Engine Electrical - Hummer H2

Charge Indicator Always On

CHARGE INDICATOR INOPERATIVE

Charge Indicator Inoperative

Step

Action

Yes

No

1

Did you perform the Diagnostic System Check for Starting
and Charging?

Go to

Step 2

Go to Diagnostic System

Check - Engine Electrical

2

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

2. Observe the Charge indicator on the instrument

cluster (IPC).

Does the charge indicator illuminate?

Go to

Step 3

Go to Symptoms - Engine

Electrical

3

1. Turn OFF the ignition.

2. Disconnect the generator connector.

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

Does the charge indicator illuminate?

Go to

Step 4

Go to Charging System

Test (CS/AD/SI

Generators)

4

Test the charge indicator control circuit for a short to
ground. Refer to Circuit Testing and Wiring Repairs in
Wiring Systems.
Did you find and correct the condition?

Go to

Step 6

Go to Step 5

5

Replace the PCM. Refer to Powertrain Control Module
(PCM) Replacement in Engine Controls.Is the action
complete?

IMPORTANT:

The replacement PCM must be programmed.

Go to

Step 6

-

6

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

System

OK

Go to Step 3

Step

Action

Yes

No

1

Did you perform the Diagnostic System
Check for Starting and Charging?

Go to Step 2

Go to Diagnostic

System Check -

Engine Electrical

2

Turn ON the ignition, with the engine OFF.
Does the battery charge indicator illuminate
during the bulb check?

Go to Testing for Intermittent

Conditions and Poor

Connections in Wiring

Systems

Go to Step 3

3

Replace the charge indicator bulb. Refer to
Instrument Panel Cluster (IPC)
Replacement in Instrument Panel, Gauges
and Console.
Did you complete the replacement?

Go to Step 4

-

2004 Hummer H2

2004 ELECTRICAL Engine Electrical - Hummer H2

GENERATOR NOISE DIAGNOSIS

Diagnostic Aids

Noise from a generator may be due to electrical or mechanical noise. Electrical noise (magnetic whine) usually
varies with the electrical load placed on the generator and is a normal operating characteristic of all generators.
When diagnosing a noisy generator, it is important to remember that loose or misaligned components around
the generator may transmit the noise into the passenger compartment and that replacing the generator may not
solve the problem.

Generator Noise Diagnosis

4

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

System OK

Go to Step 2

Step

Action

Yes

No

1

Test the generator for proper operation using the Generator Tester. Refer to
Charging System Test (CS/AD/SI Generators) .
Is the generator operating properly?

Go to

Step 2

Go to

Step

11

2

1. Start the engine. Verify that the noise can be heard.

2. Turn OFF the engine.

3. Disconnect the 4-way connector from the generator.

4. Start the engine.

5. Listen for the noise.

Has the noise stopped?

Go to

Step 11

Go to

Step 3

3

Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement in
Engine Controls.Is the action complete?

IMPORTANT:

The replacement PCM must be programmed.

Go to

Step 4

Go to

Step

11

4

Inspect the generator for a loose pulley and/or pulley nut.
Is the generator pulley or pulley nut loose?

Go to

Step 11

Go to

Step 5

5

1. Loosen all of the generator mounting bolts.

2. Tighten the generator mounting bolts to specifications and in the proper

sequence (if necessary). Refer to Generator Replacement .

3. Install the drive belt. Refer to Drive Belt Replacement - Accessory in

Engine Mechanical.

4. Start the engine.

Has the noise decreased or stopped?

System

OK

Go to

Step 6

Inspect the generator for the following conditions:

2004 Hummer H2

2004 ELECTRICAL Engine Electrical - Hummer H2