Hummer H2. Manual - part 1504

display will indicate YES in the Completed column.

For example, when the HO2S Heater Status indicates YES, either all of the oxygen sensor heater tests have 
passed or one of the tests has illuminated the MIL. If the vehicle has four heated oxygen sensors, either all four 
heater circuit tests have passed or one of the heater circuit tests has illuminated the MIL. The I/M System Status 
will indicate NO under the Completed column when any of the required tests for that system have not run. The 
following is a list of conditions that would set the I/M System Status indicator to NO: 

z

The vehicle is new from the factory and has not yet been driven through the necessary drive conditions to 
complete the tests.  

z

The battery has been disconnected or discharged below operating voltage.  

z

The control module power or ground has been interrupted.  

z

The control module has been reprogrammed.  

z

The control module DTCs have been cleared.  

Monitored Emission Control Systems 

The OBD II System monitors all emission control systems that are on-board. Not all vehicles have a full 
complement of emission control systems. For example, a vehicle may not be equipped with secondary air 
injection (AIR) or exhaust gas recirculation (EGR). The OBD II regulations require monitoring of the 
following: 

z

The air conditioning system  

z

The catalytic converter efficiency  

z

Comprehensive component monitoring-Emission related inputs and outputs  

z

The evaporative emissions (EVAP) system  

z

The EGR System  

z

The fuel delivery system  

z

Heated catalyst monitoring  

z

Misfire monitoring  

z

The oxygen sensor system (O2S or HO2S)  

z

The oxygen sensor heater system (HO2S heater)  

z

The AIR system  

For the specific DTCs required for each system, refer to Inspection/Maintenance (I/M) System DTC Table . 
Systems such as fuel delivery, misfire, and comprehensive components may not be listed in a system status list. 
These tests run continuously and do not require an I/M System Status indicator. 

Inspection/Maintenance (I/M) System Check 

Step

Action

Value

(s)

Yes

No

1. Perform Diagnostic System Check - 

Engine Controls . 

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

  

INSPECTION/MAINTENANCE (I/M) COMPLETE SYSTEM SET PROCEDURE 

Description 

The purpose of the inspection maintenance (I/M) Complete System Set Procedure is to satisfy the enable criteria 
necessary to execute all of the I/M readiness diagnostics, and to complete the trips for those particular 
diagnostics. When all diagnostic tests are completed, the I/M System Status indicators are set to YES. Perform 
this test when more than one or all of the I/M System Status indicators are set to NO. 

Conditions for Running 

Cold Start 

z

The barometric pressure (BARO) is more than 75 kPa. 

1

2. Repair any DTCs or driveability 

concerns that would prevent the I/M 
System Status tests from completing.  

Did you find and repair a DTC or driveability 
concern?

IMPORTANT:

Many DTC related repairs will 
instruct the technician to clear the 
DTC information. This procedure will 
reset ALL of the I/M System Status 
indicators to NO, and require 
performing the I/M Complete System 
Set Procedure.

-

Go to Step 3

Go to Step 2

2

1. Review any service bulletins for 

software updates that may prevent 
inspection/maintenance (I/M) 
readiness.  

2. Perform any reprogramming or repairs 

indicated by the service bulletins.  

Was a reprogramming or repair service 
required?

-

Go to 

Inspection/Maintenance 

(I/M) Complete System Set 

Procedure

Go to Step 3

3

Observe the I/M System Status display with a 
scan tool. 
Is more than one test indicating a NO status?

-

Go to 

Inspection/Maintenance 

(I/M) Complete System Set 

Procedure

Go to the I/M 

System Set 

Procedure for 

the indicated 

systems that 

have not 

updated

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

  

z

The engine coolant temperature (ECT) is between 4-30°C (39-86°F).  

z

The intake air temperature (IAT) is between 4-30°C (39-86°F).  

z

The difference between the IAT and the ECT is 8°C (14°F) or less.  

z

The battery voltage is between 10-18 volts.  

z

The fuel level is between 15-85 percent.  

Diagnostic Aids 

Rough road conditions may prevent some of the tests from running. Extreme high or low ambient temperatures 
may prevent tests such as for the heated oxygen sensor (HO2S) heater and the evaporative emission (EVAP) 
system from initiating. If a step is interrupted before completion, perform the remaining portion of the set 
procedures. Any portion of the set procedure that requires the engine at operating temperature may be repeated. 
This allows most of the diagnostics to run and the remaining tests can be performed using the individual System 
Set Procedures. 

The scan tool can be used in order to monitor each of the I/M System Status indicators during the I/M Complete 
System Set Procedure. When all of the indicators for a test step have updated to YES, testing can move on to 
the next step even if the remaining portion of the test is not complete. For example, step 3 is designed to run the 
EVAP, AIR, and HO2S tests. The procedure instructs the technician to operate the vehicle in the enable 
conditions for 6 minutes. If all 3 tests have updated to YES within 4 minutes, you do not need to continue with 
the enable conditions and testing can advance to the next step. 

Test Description 

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

2: This step is to run the HO2S heater tests and initiate the EVAP System Test. Preprogramming the scan 
tool will reduce the amount of time the oxygen sensor heaters operate while verifying the enable criteria.  

3: This step is to run the EVAP, the AIR and the oxygen sensor tests. The EVAP test begins once the 
engine coolant reaches a calibrated temperature. The AIR test, if equipped, begins shortly after Closed 
Loop and the indicated speed is achieved. The oxygen sensor tests begin once the engine is at operating 
temperature, in Closed Loop Fuel Control, and a calibrated amount of time has elapsed.  

4: This step is to run the Catalyst Tests. This test runs during the idle period immediately following a 
cruise period that meets a minimum calibrated RPM and time period.  

Inspection/Maintenance (I/M) Complete System Set Procedure 

Step

Action

Value

(s)

Yes

No

CAUTION:

Refer to Road Test Caution in Cautions and Notices.

1

Did you perform the Inspection/Maintenance 
(I/M) System Check?

-

Go to Step 2

Go to 

Inspection/Maintenance 

(I/M) System Check

IMPORTANT:

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2

  

2

1. Preprogram the scan tool with the 

vehicle information before the ignition is 
turned ON.  

2. Ensure that the vehicle is within the 

Conditions for Running specified in the 
supporting text.  

3. Turn OFF all of the accessories, 

including the A/C, and blower fan.  

4. Set the vehicle parking brake.  

5. Verify the transmission is in Park for 

automatic transmissions and Neutral for 
manual transmissions.  

6. Start the engine and allow it to idle for 

the specified time.  

Is the action complete?

Whenever the ignition is turned ON, 
ignition positive voltage is supplied to 
the heated oxygen sensor (HO2S) 
heaters. After verifying the enable 
criteria, turn OFF the ignition for 
approximately 5 minutes in order to 
allow the sensors to cool before 
continuing with the test. Once the 
engine is started, DO NOT turn the 
engine OFF for the remaining portion 
of the set procedure.

2 

minutes

Go to Step 3

-

3

In order for the next group of tests to run, the 
vehicle must operate in the following 
conditions: 

1. Acceleration at part throttle to 90 km/h 

(55 mph), with this speed maintained 
until the engine reaches operating 
temperature. This may be up to 10 
minutes depending on the start up 
coolant temperature.  

2. Continue operation under these 

conditions for an additional 6 minutes.  

 
Is the action complete?

-

Go to Step 4

-

In order for the next group of tests to run, the 
vehicle must operate in the following 
conditions: 

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls (Troubleshooting) - 4.8L, 5.3L, and 6.0L - Hummer H2