Hummer H3. Manual — part 986

mechanical condition.

3: This step determines if the differential lock high control circuit is shorted to power and if
the differential low reference circuit is shorted to ground.

4: This step indicates the transfer case shift control module needs replaced.

5: This step checks for the possibility of the rear differential mechanically binding causing it
to stay on.

Electronic Rear Differential Lock Will Not Disengage

Step

Action

Yes

No

Schematic Reference: Differential Lock Schematics
Connector End View Reference: Rear Axle Connector End Views

1

Did you perform the Diagnostic System
Check-Vehicle?

Go to Step 2

Go to
Diagnostic
System Check
- Vehicle

2

Disconnect the rear differential lock harness
from the rear differential lock coil pigtail at
the rear differential and verify the fault is
present. Refer to Locking Differential
Diagnosis.
Does the system operate normally?

Go to Step 3

Go to Step 5

3

Check the rear differential lock high control
circuit for a short to power and the
differential lock low reference for a short to
ground. Refer to Circuit Testing and Wiring
Repairs .
Was the condition found and corrected?

Go to Step 6

Go to Step 4

4

Replace the transfer case shift control module.
Refer to Control Module References for
replacement, setup and programming.
Was the repair completed?

Go to Step 6

-

5

Replace the electronic locking differential
locking mechanism and/or side gear. Refer to
Locking Differential Disassemble and
Locking Differential Assemble.
Was the condition repaired?

Go to Step 6

-

1. Use the scan tool in order to clear the

DTCs.

2007 Hummer H3

2007 Driveline/Axle Rear Drive Axle - H3

REPAIR INSTRUCTIONS

REAR AXLE LUBRICANT LEVEL INSPECTION

1. Raise the vehicle. Refer to Lifting and Jacking the Vehicle .

2. Ensure the vehicle is level.

3. Inspect the rear axle for leaks. Repair as necessary.

4. Clean the area around the rear axle fill plug.

5. Remove the rear axle fill plug.

6. Inspect the lubricant level.

Specification: The lubricant level should be between 0-10 mm (0-0.4 in) below the fill
plug opening.

7. If the level is low, add lubricant until the level is even with the bottom edge of the fill plug

opening. Use the proper fluid. Refer to Fluid and Lubricant Recommendations .

8. Install the rear axle fill plug.

Tighten: Tighten the rear axle fill plug to 33 N.m (24 lb ft).

6

2. Operate the vehicle within the

Conditions for allowing the symptom to
re-occur.

Does the symptom re-occur?

Go to Step 1

System OK

NOTE:

Refer to FASTENER NOTICE .

Use the correct fastener in the correct location. Replacement
fasteners must be the correct part number for that application.
Fasteners requiring replacement or fasteners requiring the use
of thread locking compound or sealant are identified in the
service procedure. Do not use paints, lubricants or corrosion
inhibitors on fasteners or fastener joint surfaces unless
specified. These coatings affect fastener torque and joint
clamping force and may damage the fastener. Use the correct
tightening sequence and specifications when installing
fasteners in order to avoid damage to parts and systems.

2007 Hummer H3

2007 Driveline/Axle Rear Drive Axle - H3

9. Lower the vehicle.

REAR AXLE LUBRICANT REPLACEMENT

Removal Procedure

Fig. 16: Identifying Rear Axle Drain Plug
Courtesy of GENERAL MOTORS CORP.

2007 Hummer H3

2007 Driveline/Axle Rear Drive Axle - H3

1. Clean the area around the rear axle fill plug.

2. Remove the rear axle drain plug and drain the lubricant into a suitable container.

Fig. 17: View Of Rear Axle Cover
Courtesy of GENERAL MOTORS CORP.

3. Remove the rear axle cover. Refer to Rear Axle Housing Cover and Gasket

Replacement.

Installation Procedure

2007 Hummer H3

2007 Driveline/Axle Rear Drive Axle - H3