Hummer H1 (2006+). Manual - part 337

12-24

Electrical System

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5.

If the voltage drops below the minimum value listed, replace the battery.

Parasitic Draw Test

Tools Required:

• J–38758 Parasitic Draw Test Switch

• J–39200 Digital Multimeter

1.

Remove the negative battery cable from the rear battery.

2.

Install the male end of the parasitic draw test switch over the crossover negative battery cable using the long battery bolt from
the battery cable removed in step 1.

3.

Open the parasitic draw test switch

4.

Connect the negative battery cable to female end of the parsitic draw test switch using a short battery bolt.

5.

Close the parsitic draw test switch.

6.

Road test the vehicle while activating all accessories, such as the radio and air conditioning.

7.

Turn the ignition switch to the off position and remove the key.

NOTE: It is important that from this point on, electrical continuity must be maintained in the ground circuit to the battery, either
through J–38758 in the on position, or through J–39200. 

8.

Some components, such as the ECM or TCM, have timers that draw several amps of current while they cycle down. This can
give a false parasitic drain reading. Wait 15 minutes for these components to power down before continuing this test.

NOTE: If another DVOM, is being used other than J–39200, ensure that the ammeter will handle 10 amps of current without dam-
age.

9.

Install a jumper wire with a 10 amp fuse between the two terminals on the parasitic draw test switch. Open the switch and wait
10 seconds. If the fuse does not blow, the parasitic load is less than 10 amps and the J–39200 can be used. Close the switch on
the tester and remove the jumper wire and fuse.

10. Set J–39200 to the 10 amp scale and place leads in the correct ports in the meter for amperage testing on the 10 amp scale.

11. Connect the meter leads to the two terminals on the parasitic load test switch and open the switch.

12. Wait 60 seconds then take a reading from the meter. If the current reading is at or below 2 amps, turn the test switch to the on

position. Reset the meter to read milliamps.

13. Open the switch and take the reading in milliamps.

14. Find the reserve capacity of the batteries on the vehicle. Since there are 2 batteries, add the reserve capacities together. (100

minutes + 100 minutes = 200 minutes reserve capacity). Divide the number by 4 and the answer, given in milliamps, is the
maximum allowable parasitic drain the batteries will support.

NOTE: Always turn the 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.

15. If current draw is too high, remove system fuses one at a time until the draw returns to a value less than or equal to the

maximum allowable for the batteries. Repeat the test for parasitic drain after any repair has been performed.

16. When the cause of excessive current draw has been located and repaired, remove the meter, test switch and terminal adapters

and connect the negative battery cable to the battery.

BATTERY CABLE REPLACEMENT 

Battery Negative Cables - Removal

1.

Remove the caps from the battery negative cable (Figure 12-24).

2.

Remove the battery cable bolts.

3.

Disconnect the winch negative cable, if equipped.

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 Electrical System  12-25

Figure 12-24:   Battery Negative Cable Connections 

4.

Remove the starter bolt securing the negative cable to the starter and remove the negative cable (Figure 12-25).

Figure 12-25:   Negative Cable to Cylinder Block Attachment 

NEGATIVE CABLE

CABLE BOLT

BOOT

BATTERY

CABLE

BOLT

BATTERY

TO STARTER

NEGATIVE

CABLE

05-P12-001

NEGATIVE CABLE

TO BATTERY

STARTER BOLT

12-26

Electrical System

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Battery Negative Cables - Installation 

1.

Connect the negative cables to the starter, and the batteries.

2.

Tighten the battery cable bolts to 8-12 lb-ft. (11-16 N•m).

3.

Install the caps on the battery cable bolts.

Battery Positive Cable - Removal

1.

Disconnect the battery negative cables.

2.

Remove the caps from the battery positive cable(s) (Figure 12-26).

3.

Disconnect the starter cable at the battery.

4.

Disconnect the battery positive cable, and the winch cable, if equipped, at the battery.

5.

Remove the locknut, washer, capscrew, and the clamp securing the starter cable to the bracket.

6.

Disconnect the starter cable at the starter.

Figure 12-26:   Battery Positive Cable Connections 

Battery Positive Cables - Installation

1.

Connect the starter cable to the starter with the lockers and the nut. Tighten the nut to 12-16 lb-ft (16-22 N•m).

2.

Secure the starter cable to the bracket with the clamp, capscrew, washer, and the locknut.

3.

Connect the battery positive cable to the battery.

4.

Connect the winch cable to the battery positive post (Figure 12-26).

5.

Connect the battery negative cables.

6.

Tighten the cable-to-battery bolts to 8-12 lb-ft. (11-16 N•m).

BATTERY REPLACEMENT 

WARNING:  Battery electrolyte contains sulfuric acid which can cause severe burns. If acid contacts eyes or skin,
flush affected areas liberally with water and obtain medical assistance immediately. If acid contacts clothing, flush
with water and replace affected clothing. Always wear eye protection, and remove all jewelry before working on bat-
teries.

BATTERY

CAP

BATTERY

CABLE BOLT

BATTERY

POSITIVE CABLE

CABLE

BOLT

05-P12-001

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 Electrical System  12-27

Figure 12-27:   Battery Removal/Installation 

1.

Disconnect the battery cables.

2.

Remove the J-hook, and the holddown bracket bolts (Figure 12-27).

BATTERY

HOLDDOWN

BRACKET

BATTERY TRAY

J-HOOK

BATTERY

AIR LIFT 

BRACKET