Hummer H2. Manual - part 2650

Transfer Case Shift Control Module - C3 Terminal Identification 

Transfer Case Shift Control Switch - C1 Terminal Identification 

B7

-

-

Not Used

B8

GY

596

5-Volt Reference

Connector Part Information

z

12052856  

z

4-Way F Metri-Pack 280 Series (BK)  

Pin

Wire Color

Circuit No.

Function

A

BK

1550

Ground

B

OG

1640

Battery Positive Voltage

C

RD

1553

Motor Control A

D

BK

1552

Motor Control B

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2

  

Transfer Case Shift Control Switch - C2 Terminal Identification 

DIAGNOSTIC INFORMATION AND PROCEDURES 

DIAGNOSTIC STARTING POINT - TRANSFER CASE 

Begin the system diagnosis with the Diagnostic System Check - Transfer Case . The Diagnostic System 
Check will provide the following information:

Connector Part Information

z

12064862  

z

8-Way F Metri-Pack 150 Series (BK)  

Pin

Wire Color

Circuit No.

Function

A

BK

1050

Ground

B

PK

1561

Differential Lock Indicator Control

C

BN

1560

Neutral Indicator Control

D

-

-

Not Used

E

PU/WH

1382

4LO LED Dimming Signal

F

BN/WH

230

Instrument Panel Lamps Dimming Control

G

BN

241

Ignition 3 Voltage

H

L-BU

1693

Switch Signal

Connector Part Information

z

12045813  

z

4-Way F Metri-Pack 150 Series (WH)  

Pin

Wire Color

Circuit No.

Function

A

GY

596

5-Volt Reference

B

L-GN/BK

1563

4 'HI' Indicator - Control

C

PU/WH

1565

4 'LO' Indicator - Control

D

TN/BK

1566

4 'HI' Indicator - Control

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2

  

z

The identification of the control modules that command the system  

z

The ability of the control modules to communicate through the serial data circuit  

z

The identification of any stored DTCs and their status  

The use of the Diagnostic System Check will identify the correct procedure for diagnosing the system and 
where the procedure is located. 

DIAGNOSTIC SYSTEM CHECK - TRANSFER CASE 

These diagnostic procedures will help you to find and repair full time 4WD transfer case (FT4WD) system 
malfunctions. This service category also contains information for repairing FT4WD system malfunctions. For 
best results, use the diagnostic tables, and follow the sequence listed below: 

1. Perform the Transfer Case Diagnostic System Check. All FT4WD diagnostics must begin with the 

Transfer Case Diagnostic System Check. The Transfer Case Diagnostic System Check determines the 
following: 

z

Proper SERVICE 4WD indicator operation.  

z

Ability of the transfer case shift control module to communicate through the data link connector 
(DLC)  

z

Existence of FT4WD DTCs  

2. Refer to the diagnostic table as directed by the Transfer Case Diagnostic System Check. The diagnostic 

tables will help enable you to diagnose any FT4WD system malfunction. Bypassing these procedures 
may result in the following: 

z

Extended Diagnostic Time  

z

Incorrect Diagnosis  

z

Incorrect Parts Replacement  

3. Repeat the Transfer Case Diagnostic System Check after you perform any repair or diagnostic 

procedures. This will verify that you correctly performed the repair. This will also ensure that other 
malfunctions do not exist.  

Test Description 

The numbers below refer to the step numbers on the diagnostic table. 

2: Lack of communication may be due to a partial malfunction of the class 2 serial data circuit or due to a 
total malfunction of the class 2 serial data circuit. The specified procedure will determine the particular 
condition.  

3: A fuse failure will cause no communication this step has you check for this condition.  

4: This step determines if the fuse blows when the ignition is turned on.  

5: This step determines if there is a short to ground in the battery positive circuit causing the fuse to blow. 

6: This step refers to the table for DTC C0306 for further diagnosis if a transfer case mode change is 
causing the fuse to blow.  

7: The presence of DTCs indicates that the transfer case shift control module has detected a fault. Go to 

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2

  

symptoms for other concerns.  

8: The presence of DTCs which begin with "U" indicate some other module is not communicating. The 
specified procedure will compile all the available information before tests are performed.  

9: Vehicle speed is provided to the transfer case shift control module via Class 2 and can effect the setting 
of DTC C0300. Perform the diagnostics for powertrain DTCs P0502 and P0503 first.  

Diagnostic System Check - Transfer Case 

Step

Action

Yes

No

1

Install a scan tool. 
Does the scan tool power up?

Go to Step 2

Go to Scan Tool Does Not 

Power Up in Data Link 

Communications

2

1. Turn ON the ignition, with 

the engine OFF.  

2. Attempt to establish 

communication with the 
transfer case shift control 
module.  

Does the scan tool communicate 
with the transfer case shift control 
module?

Go to Step 7

Go to Step 3

3

1. Turn off the ignition.  

2. Check the underhood 

TREC fuse.  

Did the TREC fuse blow?

Go to Step 4

Go to Scan Tool Does Not 

Communicate with Class 2 

Device in Data Link 

Communications

4

Replace the TREC fuse. 
Does the ATC fuse blow 
immediately?

Go to Step 5

Go to Step 6

5

Check the battery positive circuit 
for a short to ground. 
Was the condition found and 
corrected?

Go to Step 2

Go to Transfer Case Shift 

Control Module Replacement.

6

1. Start the Engine  

2. Attempt to shift the transfer 

case to different modes.  

3. Check the underhood 

TREC fuse.  

Did the TREC fuse blow?

Go to DTC C0306

Go to Step 2

7

Select the transfer case shift 
control module display DTCs 
function on the scan tool. 

 

2004 Hummer H2 

2004 DRIVELINE/AXLE Transfer Case - BW 4484 - Hummer H2