Hummer H2. Manual - part 1084

16. Operate system to verify repair. If system is not operating correctly, repeat test beginning at step 3 .  

Fig. 1: Identifying Generator 4-Pin Connector Terminals 
Courtesy of GENERAL MOTORS CORP. 

TEST B: CHARGE INDICATOR ALWAYS ON 

1. If diagnostic system check was not performed, perform ENGINE ELECTRICAL DIAGNOSTIC 

SYSTEM CHECK under ON-VEHICLE TESTING. If diagnostic system check was performed, go to 
next step.  

2. Turn ignition switch to RUN position. If charge indicator illuminates, go to step 3 . If charge indicator 

does not illuminate, repair by symptom. See SYMPTOM INDEX table. 

 

2004 Hummer H2 

2003-04 STARTING & CHARGING SYSTEMS Generators & Regulators - H2

  

3. Turn ignition switch to OFF position. Disconnect 4-pin generator harness connector. Turn ignition switch 

to RUN position. If charge indicator illuminates, go to next step. If charge indicator does not illuminate, 
perform TEST A: CHARGING SYSTEM TEST .  

4. Test Brown wire for short to ground. See WIRING DIAGRAMS . If problem exists, repair as necessary. 

After repair, go to step 6 . If problem does not exist, go to next step.  

5. Replace PCM. See REMOVAL, OVERHAUL & INSTALLATION - TRUCKS article in ENGINE 

PERFORMANCE. Program PCM. After repair, go to next step.  

6. Operate system to verify repair. If system is not operating correctly, repeat test beginning at step 3 .  

TEST C: CHARGE INDICATOR INOPERATIVE 

1. If diagnostic system check was not performed, perform ENGINE ELECTRICAL DIAGNOSTIC 

SYSTEM CHECK under ON-VEHICLE TESTING. If diagnostic system check was performed, go to 
next step.  

2. Turn ignition switch to RUN position. If charge indicator light does not illuminate, go to next step. If 

charge indicator light illuminates, problem is intermittent. Check wiring and connections.  

3. Replace charge indicator bulb. See appropriate ANALOG INSTRUMENT PANELS article in 

ACCESSORIES & EQUIPMENT. After repair, go to next step.  

4. Operate system to verify repair. If system is not operating correctly, repeat test beginning at step 2 .  

TEST D: GENERATOR NOISE DIAGNOSIS 

1. Test generator for proper operation. See TEST A: CHARGING SYSTEM TEST . If generator is 

operating properly, go to next step. If generator is not operating properly, go to step 11 .  

2. Start engine. Verify that generator noise can be heard. Turn switch to OFF position. Disconnect generator 

4-pin harness connector. Start engine. Listen for generator noise. If noise does not exist, go to step 11 . If 
noise still exist, go to next step.  

3. Turn switch to OFF position. Remove drive belt. Spin generator pulley by hand. If pulley rotates 

smoothly and noise does not exist, go to next step. If pulley rotates roughly and/or noise exists, go to step 
11 .  

4. Inspect pulley for looseness, or loose pulley nut. If pulley and nut are okay, go to next step. If pulley 

and/or nut is loose, go to step 11 .  

5. Loosen all generator mounting bolts. Tighten all mounting bolts to specification. See TORQUE 

SPECIFICATIONS . Install drive belt. Start engine and listen for noise. If noise has decreased or 
stopped, system is okay. If noise still exists, go to next step.  

6. Check for stretched generator connections, or hoses or other equipment rubbing on generator. If problem 

exists, repair as necessary. After repair, go to next step. If problem does not exist, go to step 8 .  

7. Reroute electrical connections, hoses, etc., away from generator. Start engine and listen for noises. If 

noise has decreased or stopped, system is okay. If noise still exists, go to next step.  

8. Check drive belt for proper tension. If drive belt is loose, go to next step. If drive belt is okay, go to step 

10 .  

9. Replace drive belt tensioner. Start engine and listen for noise. If noise has decreased or stopped, system is 

okay. If noise still exists, go to step 11 . 

 

2004 Hummer H2 

2003-04 STARTING & CHARGING SYSTEMS Generators & Regulators - H2

  

10. Check comparable vehicle for similar noise. If noise exists in similar vehicle, system is okay. If noise 

does not exist in similar vehicle, go to next step.  

11. If no definite generator problems were found, ensure all other possible sources of noise are eliminated. If 

all possibilities have been eliminated, replace generator. See GENERATOR under REMOVAL & 
INSTALLATION. After repair, go to next step.  

12. Start engine and verify that noise is reduced or eliminated. If noise is still objectionable, go to step 2 .  

ON-VEHICLE TESTING 

BATTERY TESTING & INSPECTION 

1. Inspect battery for a cracked, broken or damaged case. If battery case is okay, go to next step. If battery 

case is not okay, go to step 19 .  

2. Compare battery Cold Cranking Amperage (CCA) and Reserve Capacity (RC) rating to specifications. 

See BATTERY SPECIFICATIONS . If battery meets or exceeds specifications, go to next step. If 
battery does not meet or exceed specifications, go to step 19 .  

3. Inspect battery hydrometer display. If hydrometer display shows a Yellow dot, go to next step. If 

hydrometer display does not show a Yellow dot, go to step 5 .  

4. Using a small screwdriver, tap the top of hydrometer display to dislodge any air bubbles inside. If 

hydrometer display still shows a Yellow dot, go to step 19 . If hydrometer display does not show a 
Yellow dot, go to next step.  

5. Turn ignition switch to OFF position. Attempt to rotate negative battery cable connector clockwise with 

light finger pressure. If negative connector rotates, go to next step. If negative connector does not rotate, 
go to step 7 .  

6. Using an INCH lb. torque wrench, record torque value while loosening negative battery cable bolt. If 

CAUTION: When battery is disconnected, vehicle computer and memory systems 

may lose memory data. Driveability problems may exist until computer 
systems have completed a relearn cycle. See appropriate COMPUTER 
RELEARN PROCEDURES article in GENERAL INFORMATION before 
disconnecting battery. 

NOTE:

Before making electrical checks, visually inspect all terminals for clean, tight 
connections. Ensure all charging system related fuses are okay. Check 
generator mounting bolts and drive belt tension. Ensure battery is in good 
condition prior to testing charging system. Ensure starting system is okay. See 
appropriate STARTERS article. 

NOTE:

Connector Test Adapter Kit (J-35616-A) must be used whenever a test 
procedure requires checking or probing terminal. 

NOTE:

Manufacturer recommends using Battery Tester (J-42000) for testing battery. 
Follow instructions provided with tester. 

 

2004 Hummer H2 

2003-04 STARTING & CHARGING SYSTEMS Generators & Regulators - H2

  

torque is equal to or greater than 88 INCH lbs. (10 N.m), go to step 8 . If torque is less than 88 INCH lbs. 
(10 N.m), go to next step.  

7. Disconnect negative battery cable and go to step 9 .  

8. Disconnect negative battery cable. Inspect battery and cable terminals for corrosion and defects. Repair as 

necessary. Go to next step.  

9. Attempt to rotate positive battery cable connector clockwise with light finger pressure. If battery cable 

rotates, go to next step. If battery cable does not rotate, go to step 11 .  

10. Using an INCH lb. torque wrench, record torque value while loosening positive battery cable bolt. If 

torque is equal to or greater than 88 INCH lbs. (10 N.m), go to step 12 . If torque is below 88 INCH lbs. 
(10 N.m), go to next step.  

11. Disconnect positive battery cable and go to step 13 .  

12. Disconnect positive battery cable. Inspect battery and cable terminals for corrosion and defects. If 

problem exists, repair as necessary. After repair, go to next step.  

13. Clean and wire brush lead face of both battery terminals and metal contact surfaces on both cable 

connectors. Remove bolts from both battery cable connectors and inspect for corrosion and defects. 
Repair or replace as necessary. If battery and cables terminals are clean and in good condition, go to next 
step.  

14. Connect positive battery cable to battery and tighten bolt to 11 ft. lbs. (15 N.m). After repair, go to next 

step.  

15. Connect negative battery cable to battery and tighten bolt to 11 ft. lbs. (15 N.m). After repair, go to next 

step.  

16. Ensure all electrical loads are off. Follow manufacturer's instructions and install Battery Tester (J-42000) 

to vehicle battery. Follow any instructions displayed on Battery Tester. If Battery Tester passed battery, 
go to next step. If Battery Tester did not pass battery, go to step 18 .  

17. Press CODE button on battery tester. Record displayed code on vehicle repair order for warranty 

purposes. Battery is okay.  

18. Press CODE button on Battery Tester. Record displayed code on vehicle repair order for warranty 

purposes. Replace battery.  

19. Replace battery.  

BATTERY SPECIFICATIONS 

BATTERY SPECIFICATIONS 

ENGINE ELECTRICAL DIAGNOSTIC SYSTEM CHECK 

1. Perform battery inspection test. See BATTERY TESTING & INSPECTION under ON-VEHICLE 

Application 

Specification 

GM P/N 19001810 

Replacement Battery Number 

79-6YR 

Cold Cranking Amps 

880 Amps 

Reserve Capacity Rating 

115 Minutes 

 

2004 Hummer H2 

2003-04 STARTING & CHARGING SYSTEMS Generators & Regulators - H2