Hummer H3. Manual — part 39

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.

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

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.

BATTERY ELECTRICAL DRAIN/PARASITIC LOAD TEST

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 ECM/PCM or other electronic components.

NOTE:

Refer to Fastener Notice .

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.

2008 Hummer H3

2008 ENGINE Engine Electrical - H3

Special Tools

J 38758 Parasitic Draw Test Switch. See Special Tools.

Diagnostic Aids

Be sure to rule out any possible obvious influences, such as customer error or aftermarket
equipment.

Customer driving habits, such as regular short trips. This does not allow enough time to
properly charge the battery. Refer to Battery Description and Operation.

Verify that the battery and charging system are in proper working order. Refer to Battery
Charging and Charging System Test.

A battery discharging for no apparent reason while the vehicle is parked can be caused by
an intermittent draw, such as a module waking up, or a continuous draw, such as a dome
light or stuck relay.

Some systems and modules such as OnStar®, and regulated voltage control (RVC), are
designed to wake-up, perform a task, and go back to sleep at regular intervals. Refer to
Body Control System Description and Operation for the system or modules description
and operation.

Remote keyless entry (RKE) will wake up due to an outside input. Refer to Keyless Entry
System Description and Operation for the system description and operation.

The battery run down time will vary depending on cold cranking amperage (CCA) and
reserve capacity (RC). If the CCA and RC are higher, then the battery run down time would
be longer. If the CCA and RC are lower, then the battery run down time would be shorter.
The graph below indicates roughly how many days a 690 CCA battery with at 110 min. RC
(60.5 AH) starting at 80 percent state of charge will last with a constant current draw until it
reaches 50 percent state of charge. Differences in battery rating and temperature will affect
the results.

IMPORTANT: The battery specification listed below is a generic

specification. Refer to Battery Usage when testing the
battery.

Current Drain

Days

25 mA

30.5

50 mA

16.5

75 mA

11

100 mA

8.25

2008 Hummer H3

2008 ENGINE Engine Electrical - H3

Load Test

1. Disconnect the battery negative cable from the battery negative terminal. Refer to Battery

Negative Cable Disconnection and Connection.

2. Install the female end of the J 38758 to the battery ground terminal. See Special Tools.

3. Turn the J 38758 test switch to the OFF position. See Special Tools.

4. Install the battery negative cable to the male end of the J 38758 . See Special Tools.

5. Turn the J 38758 test switch to the ON position. See Special Tools.

6. Road test the vehicle and activate ALL of the accessories, including the radio and air

conditioning. This may take up to 30 minutes.

7. Park the vehicle. Turn the ignition switch to the OFF position and remove the ignition

switch key. Unplug the scan tool and CANDI module from the vehicle, if one is present.

8. Connect a 10A fused jumper wire to the test switch tool terminals.

250 mA

3.3

500 mA

1.65

750 mA

1

1 A

0.8

2 A

0.4

CAUTION: Refer to Battery Disconnect Caution .

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.

IMPORTANT: The test switch on the J 38758 is marked ON and OFF. See

Special Tools. When the test switch is in the ON position, the
circuit is closed and electrical current will pass through the
switch. When the test switch is in the OFF position, the circuit is
open and electrical current will not pass through the switch.

2008 Hummer H3

2008 ENGINE Engine Electrical - H3

9. Turn the J 38758 test switch to the OFF position. See Special Tools. The current now

flows through the jumper wire.

10. Wait 1 minute. If the fuse opens, install an inductive ammeter to locate the current draw.

11. Turn the test switch to ON and then remove the fused jumper wire.

12. Set a digital multimeter to the 10A scale.

13. Connect the digital multimeter to the test switch tool terminals.

14. Turn the J 38758 test switch to the OFF position. See Special Tools. The current flows

now through the digital multimeter.

15. Wait 1 minute. Check and record the current reading.

1. When there is a current reading of 2A or less, turn the J 38758 test switch to the ON

position. See Special Tools. The electrical current will now pass through the switch.

2. Then switch the digital multimeter down to the 2A scale for a more accurate reading

when the J 38758 test switch is turned OFF. See Special Tools.

16. Turn the J 38758 test switch to the OFF position. See Special Tools. Wait 20 minutes for

the modules to go to sleep. Do not open any doors or turn anything on, or else the 20 minute
time will have to start over.

17. Check and record the current reading. The parasitic current drain should not exceed 75 mA.

18. If excessive current drain is not found at this time and there are no other apparent causes,

complete the following:

1. Using the MIN/MAX function of the digital multimeter, monitor the parasitic drain

overnight or during the day. This will determine if something has been activated during
that time frame.

2. When the vehicle has an unacceptable amount of parasitic current drain, remove each

fuse one at a time until the current drain falls to an acceptable level. This will indicate

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.

IMPORTANT: Removing fuses, relays, and connectors to determine the

failure area may wake up modules. You must wait for
these modules to go to sleep or use the sleep function
on the scan tool.

2008 Hummer H3

2008 ENGINE Engine Electrical - H3