Hummer H2. Manual - part 239

Does the scan tool communicate with the BCM?

Go to Step 36

33

33

1. Turn OFF the ignition.  

2. Disconnect the module that caused the no 

communication condition.  

3. Test the class 2 serial data circuit between the splice 

pack - SP205 and the respective module for a short to 
ground or a short to voltage. Turn ON the ignition 
leaving the engine OFF when testing for a short to 
voltage. Refer to Circuit Testing and Wiring 
Repairs in Wiring Systems.  

Did you find and correct the condition?

Go to Step 36

Go to Step 

34

34

Inspect for poor connections at the class 2 serial data circuit 
of the last disconnected module. Refer to Testing for 
Intermittent Conditions and Poor Connections and 
Connector Repairs in Wiring Systems. 
Did you find and correct the condition?

Go to Step 36

Go to Step 

35

35 Replace the last disconnected module. Refer to Control 

Module References in Body Control System for the 
appropriate repair instructions.Did you complete the 
replacement?

IMPORTANT:

Perform the module setup procedure if required.

Go to Step 36

-

36

1. Reconnect all of the disconnected modules.  

2. Reconnect any other disconnected connectors.  

3. Install a scan tool.  

4. Turn ON the ignition leaving the engine OFF.  

5. Wait for 10 seconds. 

The scan tool may require a power up reset before 
communication will occur due to a short on the class 2 
serial data circuit. Turn OFF the scan tool prior to 
performing this test. 

6. Select the Display DTCs function for each module. If 

using a Tech 2, use the Class 2 DTC Check feature in 
order to determine which modules do have DTCs set.  

7. Record all of the displayed DTCs and the DTC status. 

Did you record any DTCs which begin with a "U" and with 
a current status?

Go to Step 38

Go to Step 

37

37 Did you record any DTCs which do not begin with a "U"?

Go to Step 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Data Link Communications - Hummer H2

  

REPAIR INSTRUCTIONS 

DATA LINK CONNECTOR REPLACEMENT 

Removal Procedure 

1. Remove the bolts/screws from the data link connector. 

Go to Step 38

40

38

Diagnose the DTCs as directed by the diagnostic procedures 
for the particular module or malfunction. Refer to Control 
Module References in Body Control System for the 
applicable Diagnostic System Check. 
Did you complete the action?

Go to Step 39

-

39

Did you diagnose all of the DTCs?

Go to Step 40

Go to Step 

38

40

Use the scan tool in order to clear the DTCs. 
Did you complete the action?

System OK

-

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Data Link Communications - Hummer H2

  

Fig. 6: Data Link Connector 
Courtesy of GENERAL MOTORS CORP. 

2. Remove the lower data link connector.  

Installation Procedure 

1. Place the data link connector into position. 

NOTE:

Refer to Fastener Notice in Cautions and Notices.

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Data Link Communications - Hummer H2

  

Fig. 7: Data Link Connector 
Courtesy of GENERAL MOTORS CORP. 

2. Install the bolts/screws to the data link connector. 

Tighten: Tighten the bolts/screws to 2 N.m (18 lb in). 

DESCRIPTION AND OPERATION 

DATA LINK COMMUNICATIONS DESCRIPTION AND OPERATION 

Circuit Description 

The data link connector (DLC) allows a scan tool to communicate with the class 2 serial data line. The serial 
data line is the means by which the microprocessor-controlled modules in the vehicle communicate with each 
other. Once the scan tool is connected to the class 2 serial data line through the DLC, the scan tool can be used 
to monitor each module for diagnostic purposes and to check for diagnostic trouble codes (DTCs). Class 2 serial 
data is transmitted on a single wire at an average of 10.4 kbps. This value is an average, class 2 uses a variable 

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Data Link Communications - Hummer H2