Hummer H2. Manual - part 1608

and in the correct location.  

5. Inspect for aftermarket devices that 

could affect the operation of the 
system. Refer to Checking 
Aftermarket Accessories in 
Wiring Systems.  

 
Did you find and correct the condition?

System OK

Go to Step 2

2

1. Install a scan tool.  

2. Turn ON the scan tool.  

Does the scan tool turn ON?

Go to Step 3

Go to Scan Tool Does 

Not Power Up in Data 

Link Communications

3

1. Turn ON the ignition, with the 

engine OFF.  

2. Attempt to establish 

communication with the listed 
control modules. If you are using a 
Tech 2, obtain the information 
using the Class 2 Message Monitor 
feature: 

z

Powertrain control module 
(PCM)  

z

Electronic brake control 
module (EBCM)  

z

Body control module (BCM) 

Does the scan tool communicate with all 
the listed modules?

Go to Step 4

Go to Scan Tool Does 

Not Communicate with 

Class 2 Device in Data 

Link Communications

4

1. Access the Class 2 Power Mode in 

the Diagnostic Circuit Check on 
the scan tool.  

2. Rotate the ignition switch through 

all positions while observing the 
ignition switch power mode 
parameter. 

Refer to the Body Control System 

IMPORTANT:

The engine may start during the 
following step. Turn OFF the engine as 
soon as you have observed the Crank 
power mode.

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Diagnostic Information & Procedures) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

Description and Operation in 
Body Control Systems, for a list of 
the power mode states that 
correspond to each ignition switch 
position. 

Does the ignition switch parameter 
reading match the ignition switch 
position for all switch positions?

Go to Step 5

Go to Power Mode 

Mismatch in Body 

Control System

5

Attempt to start the engine. 
Does the engine crank?

Go to Step 6

Go to Symptoms - 

Engine Electrical in 

Engine Electrical

6

Did the engine start and idle?

Go to Step 7

Go to Engine Cranks 

but Does Not Run

7

1. Select the DTC display function for 

the following control modules and 
record the DTCs: 

z

PCM  

z

EBCM  

z

BCM  

2. If multiple powertrain DTCs are 

stored, diagnose the DTCs in the 
following order: 

1. Component level DTCs. 

For example, sensor DTCs, 
solenoid DTCs, and relay 
DTCs. 

Begin with the lowest 
number DTC unless the 
diagnostic table directs you 
otherwise. 

2. System level DTCs. 

For example, misfire DTCs, 
EVAP system DTCs, fuel 
trim DTCs, and system 
voltage DTCs. 

IMPORTANT:

Do NOT clear the DTCs unless 
instructed by a diagnostic procedure.

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Diagnostic Information & Procedures) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

SCAN TOOL DATA LIST 

The Engine Scan Tool Data List contains all engine related parameters that are available on the scan tool. The 
list is arranged in alphabetical order. A given parameter may appear in any one of the data lists, and in some 
cases may appear more than once, or in more than one data list in order to group certain related parameters 
together. 

Use the Engine Scan Tool Data List only after the following is determined: 

z

The Diagnostic System Check - Engine Controls is completed.  

z

No diagnostic trouble codes (DTCs)  

z

On-board diagnostics are functioning properly.  

Scan tool values from a properly running engine may be used for comparison with the engine you are 
diagnosing. The Engine Scan Tool Data List represents values that would be seen on a normal running engine. 

Only the parameters listed below are referenced in this service manual for use in diagnosis. If all values are 
within the typical range described below, refer to Symptoms - Engine Controls for diagnosis. 

The column labeled Data List indicates where a parameter can be located on the scan tool. Refer to the scan tool 
operating manual for the exact locations of the data lists. The following is a description of each term listed: 

All  

The Parameter is in all of the data lists indicated below.

3. Search for applicable service 

bulletins.  

Does the scan tool display any DTCs?

Go to Step 8

Go to Step 9

8

If there are any powertrain DTCs, select 
Capture Info to store the powertrain DTC 
information with a scan tool. 
Did you complete the action?

Go to Diagnostic Trouble 

Code (DTC) List for 

applicable diagnostic 

procedure

-

9

Is the customer's concern with 
Inspection/Maintenance (I/M) testing?

Go to 

Inspection/Maintenance 

(I/M) System Check

Go to Step 10

10

Are there any driveability symptoms 
observed?

Go to Symptoms - Engine 

Controls

System OK

IMPORTANT: A scan tool that displays faulty data should not be used. The scan tool problem 

should be reported to the manufacturer. Use of a faulty scan tool can result in 
misdiagnosis and unnecessary parts replacement.

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Diagnostic Information & Procedures) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

Eng 1  

Engine Data 1 List 

Eng 2  

Engine Data 2 List 

EE  

Enhanced Evaporative Emission (EVAP) Data 

FF/FR  

Freeze Frame/Failure Records 

FT  

Fuel Trim Data List 

MF  

Misfire Data List 

TAC  

Throttle Actuator Control (TAC) Data List 

CC  

Cruise Control Data List 

HO2S Data  

Heated Oxygen Sensor (HO2S) Data List 

Scan Tool Data List 

Scan Tool Parameter

Data List

Parameter Range/Units

Typical Data Values

Engine Idling/Radiator Hose Hot/Closed Throttle/Park or Neutral/Closed Loop/Accessories OFF

4WD Signal

Eng 2

Enabled/Disabled

Disabled

4WD Low Signal

Eng 2

Enabled/Disabled

Disabled

A/C Pressure Sensor

Eng 2

Volts

0.98 Volts/Varies

A/C Pressure Sensor

Eng 2

PSI

90 PSI/Varies

A/C Relay Command

Eng 1, 2, MF

On/Off

Off

A/C Request Signal

Eng 2

Yes/No

No

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Diagnostic Information & Procedures) - 4.8L, 5.3L, and 6.0L - 

Hummer H2