Hummer H2. Manual - part 1192

Charging Procedure 

When charging side-terminal batteries with the battery cables connected, connect the charger to the positive 
cable bolt and to a ground located away from the battery. When charging side-terminal batteries with the battery 
cables disconnected, install the battery side terminal adapters and connect the charger to the adapters. 

Tighten: Tighten the battery side terminal adapters to 15 N.m (11 lb ft). 

Use the following procedure to charge the battery: 

1. Turn OFF the charger.  

2. Ensure that all of the battery terminal connections are clean and tight.  

3. Connect the charger positive lead to the battery positive terminal on the battery or the remote jumper stud 

underhood. 

4. Connect the negative charger lead to a solid engine ground or to a ground stud in the engine compartment 

that is connected directly to the battery negative terminal, but away from the battery. If the negative 
battery cable is disconnected and a terminal adapter is being used, connect directly to the adapter.  

5. Turn ON the charger and set to the highest setting for normal charging.  

6. Inspect the battery every half hour after starting the battery charger. 

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Charge the battery until the taper-rate charger indicates that the battery is fully charged.  

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Estimate the battery temperature by feeling the side of the battery. If it feels hot to the touch or its 
temperature is over 45° C (125° F), discontinue charging and allow the battery to cool before 
resuming charging.  

7. After charging, test the battery. Refer to Battery Inspection/Test (Non-HP2) .  

BATTERY ELECTRICAL DRAIN/PARASITIC LOAD TEST (W/BCM) 

Tools Required 

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J 38758 Parasitic Draw Test Switch. See Special Tools and Equipment .  

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J 39200 Digital Multimeter  

Battery Electrical Drain 

NOTE:

Turn OFF the ignition when connecting or disconnecting the battery cables, the 
battery charger or the jumper cables. Failure to do so may damage the PCM or 
other electronic components.

NOTE:

Refer to Fastener Notice in Cautions and Notices.

NOTE:

Do not connect the negative charger lead to the housings of other vehicle 
electrical accessories or equipment. The action of the battery charger may 
damage such equipment.

 

2004 Hummer H2 

2004 ELECTRICAL Engine Electrical - Hummer H2

  

If the vehicle exhibits a low or dead battery after an overnight period, or discharges over a period of 2 or 3 days, 
the electrical system should be checked for an excessive electrical drain. This is referred to as Parasitic Current 
Drain. 

If a battery needs recharging and no cause is evident, check the vehicle for excessive parasitic current drain. 

One or more on-board solid state control modules, such as the body control module (BCM) may at some time 
exhibit a failure mode that causes a high parasitic drain on the vehicle's battery. When the battery is 
disconnected to install an ammeter, etc., the excessive current drain may not occur once the circuit continuity is 
restored. Even though cycling the ignition key to the RUN and then to the OFF position may cause such a drain 
to recur, there may be drains that will not recur unless the vehicle systems are reactivated in a road test. Since 
the ignition switch must not be rotated to the ACCESSORY, RUN or START position with an ammeter 
installed between the battery terminal and the battery cable, a current drain test tool must be used as described 
in the following procedures. 

Before starting this procedure, ensure that the ignition switch is in the LOCK position, all electrical accessories 
are turned OFF, the underhood lamp is disconnected, the door glass is open and the doors are closed. 

1. Disconnect the battery negative cable. Refer to Battery Negative Cable Disconnect/Connect Procedure 

(Single Battery) . 

CAUTION: Refer to Battery Disconnect Caution in Cautions and Notices.

NOTE:

Do not turn the parasitic draw test switch to the OFF position with the engine 
running. Damage will occur to the vehicle's electrical system.

NOTE:

The test switch must be in the ON position when removing the fuses in order to 
maintain continuity in the electrical system. This avoids damaging the digital 
multimeter due to accidental overloading, such as a door being opened to 
change a fuse.

 

2004 Hummer H2 

2004 ELECTRICAL Engine Electrical - Hummer H2

  

Fig. 5: Connecting J 39200 & J 38758 To Battery Cable 
Courtesy of GENERAL MOTORS CORP. 

2. Install the male end of the J 38758 Parasitic Draw Test Switch to the battery negative terminal. See 

Special Tools and Equipment .  

3. Turn OFF the test switch.  

4. Install the battery negative cable to the female end of the test switch.  

5. Turn ON the test switch.  

6. Road test the vehicle while activating all accessories, including the radio and the air conditioning.  

7. Turn OFF the ignition switch. Remove the key. 

IMPORTANT: From this point on, electrical continuity must be maintained in the ground 

circuit of the battery through the J 38758 in the ON position or through 
theJ 39200 . The BCM can draw several amps of current after the ignition 

 

2004 Hummer H2 

2004 ELECTRICAL Engine Electrical - Hummer H2

  

8. Install the scan tool and perform the power down now feature from the BCM output menu. After 

performing this function the scan tool can be powered off or disconnected, then wait an additional 5 
minutes before continue testing.  

9. Set the J 39200 Digital Multimeter to the 10 A scale. 

1. Connect a jumper wire with an in-line 10 A fuse J 36169-A to the terminals of the test switch.  

2. Turn the test switch to the OFF position.  

3. Wait 10 seconds.  

4. If the fuse does not blow, the current is less than 10 A and the ammeter can be used safely.  

5. Turn the test switch to the ON position before the fused jumper wire is removed and the multimeter 

is installed.  

10. Connect the ammeter to the test switch terminals.  

11. Turn OFF the test switch. This allows the current to flow through the ammeter.  

12. Wait at least 60 seconds, then check the current reading. 

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When there is a current reading of 2 A or less, turn ON the test switch, this maintains continuity in 
the electrical system.  

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Then, switch the meter down to the 2 A scale, for a more accurate reading, when the test switch is 
reopened.  

13. Take the reading in milli-amps.  

14. Note the battery reserve capacity. Refer to Battery Usage . 

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Divide this number by 4.  

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Compare this to the multimeter reading.  

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The current drain should not exceed this number.  

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Example: If a battery has a reserve capacity of 100 minutes, the current drain should not exceed 25 
milli-amps. If the vehicle has 2 batteries, add the reserve capacities together and divide this total by 
4.  

15. When the current draw is too high, remove the electrical system fuses one at a time until the draw returns 

to a value less than or equal to specifications. 

is turned off. Refer to Body Control System Description and Operation in 
Body Control System. See Special Tools and Equipment .

IMPORTANT: If an ammeter other than the J 39200 is used, ensure that the vehicle does 

not have a high current drain that would damage the ammeter when 
connected to the circuit. This can be done using the following procedure:

NOTE:

Always turn the test switch knob to the ON position before removing each 
fuse to maintain continuity in the electrical system and to avoid damaging 
the meter due to accidental overloading, such as opening a door to 
change a fuse.

 

2004 Hummer H2 

2004 ELECTRICAL Engine Electrical - Hummer H2