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