Hummer H2. Manual — part 1511

Decel. Fuel Cutoff

This parameter displays the status of the operating mode used to turn OFF the fuel injectors during certain
deceleration conditions. When the scan tool displays Active, the control module has turned OFF the fuel
injectors. When the scan tool displays Inactive, the fuel system is operating normally.

Desired IAC Airflow

This parameter displays the desired airflow in the idle air control (IAC) passage as calculated by the
control module.

Desired Idle Speed

This parameter displays the engine idle speed in RPM commanded by the control module. The control
module compensates for various engine loads in order to maintain the desired engine RPM at idle. This
parameter is not valid unless the engine is running.

DTC Set This Ignition

This parameter displays if a diagnostic trouble code (DTC) set during the current ignition cycle. The scan
tool will display YES if a DTC is stored this ignition cycle.

ECT Sensor

This parameter displays the temperature of the engine coolant based on a voltage input from the engine
coolant temperature (ECT) sensor to the control module. The scan tool will display a low value when
coolant temperature is low, and a high value when the coolant temperature is high.

Engine Load

This parameter displays the engine load in percent based on inputs to the control module from various
engine sensors. The scan tool will display a low percentage when the engine is at idle with little or no
load. The scan tool will display a high percentage when the engine is running at a high RPM under a
heavy load.

Engine Oil Level Switch

This parameter displays the state of the engine oil level switch as determined by the control module. The
scan tool will display OK or Low. OK indicates that the engine oil level is not too low for safe operation
of the engine. Low indicates the engine oil level is abnormally low and has closed the engine oil level
switch.

Engine Oil Life Remaining

This parameter displays the amount of engine oil life remaining before requiring an oil change. This
number is calculated by the control module based on many inputs and is displayed as a percent. The
lower the percentage, the sooner the next oil change will be required.

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Engine Run Time

This parameter displays the time elapsed since the engine was started. The scan tool will display the time
in hours, minutes and seconds. The engine run time will reset to zero as soon as the engine stops running.

Engine Speed

This parameter displays the speed of the crankshaft as calculated by the control module based on inputs
from the crankshaft position (CKP) sensor. The scan tool will display the engine speed in revolutions per
minute (RPM).

EVAP Purge Solenoid Command

This parameter displays the on-time or duty cycle of the evaporative emission (EVAP) purge solenoid
commanded by the control module expressed as a percent. The scan tool will display a high percentage
when the control module is commanding the EVAP purge solenoid to be open a large amount. The scan
tool will display a low percentage when the control module is commanding the EVAP purge solenoid to
be open a small amount. The scan tool will display 0 when the control module is commanding the EVAP
purge solenoid closed.

EVAP Test Result

The scan tool displays No Result, Passed, Aborted, Fail-DTC P0440, Fail-DTC P0442, Fail-DTC P0446,
or Fail-DTC P1441. The scan tool displays PASS if the control module determines that the EVAP test has
passed.

EVAP Test State

The scan tool displays Waiting For Purge, Test Running, or Test Completed. This parameter indicates the
state of the EVAP service bay test.

EVAP Vent Solenoid Command

This parameter displays the commanded state of the EVAP vent solenoid control circuit. The scan tool
will display Venting or Not Venting. Venting indicates the EVAP vent solenoid is not being commanded
on by the control module. Not Venting indicates the EVAP vent solenoid is being commanded ON by the
control module.

Fail Counter

The scan tool displays the number of times that a diagnostic has failed.

Fuel Alcohol Content

This parameter displays the percentage of alcohol in the fuel. This value is calculated by the control
module using the frequency signal from the fuel composition sensor. The scan tool will display a low
percentage when there is very little alcohol in the fuel. The scan tool will display a high percentage when

2004 Hummer H2

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

Hummer H2

the alcohol content of the fuel is high.

Fuel Composition Sensor Frequency

This parameter displays the frequency from the sensor used to monitor the concentration of alcohol in the
fuel. The fuel composition sensor measures the fuel capacitance, temperature, and fuel conductance to
determine the amount of alcohol contained in the fuel. The scan tool will display a low frequency reading
when the alcohol concentration of the fuel is low. The scan tool will display a high frequency reading
when the alcohol concentration of the fuel is high.

Fuel Composition Sensor On Time

This parameter displays the pulse width signal of the fuel composition sensor as received by the control
module. The scan tool will display a lower value at colder fuel temperatures. The scan tool will display a
higher value at higher fuel temperatures.

Fuel Level Sensor

This parameter displays the voltage from the signal produced by the sensor used to monitor the fuel level
inside the fuel tank. The scan tool will display a low voltage reading when the fuel level in the tank is low
or near empty. The scan tool will display a high voltage reading when the fuel level in the tank is high or
near full.

Fuel Level Sensor Rear Tank

This parameter displays the voltage from the signal produced by the sensor used to monitor the fuel level
inside the rear fuel tank. The scan tool will display a low voltage reading when the fuel level in the rear
tank is low or near empty. The scan tool will display a high voltage reading when the fuel level in the
tank is high or near full.

Fuel Tank Level Remaining

This parameter displays the amount of fuel remaining in all fuel tanks of the vehicle as measured in liters
or gallons. The control module calculates the amount of fuel remaining in the tank by using information
from the fuel level sensors.

Fuel Tank Level Remaining

This parameter displays the amount of fuel remaining in tall of the fuel tanks of the vehicle as a
percentage. The control module calculates this level using the signals from the sensors used to monitor
the fuel level in the fuel tanks. The scan tool will display a low reading when the total fuel level in the
vehicle is low or near empty. The scan tool will display a high reading when the fuel level in the tank is
high or near full.

Fuel Tank Pressure Sensor

This parameter indicates the pressure or vacuum in the fuel tanks as determined by the control module

2004 Hummer H2

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

Hummer H2

based on inputs from the fuel tank pressure sensor. The scan tool displays in mm/Hg or in H2O. The scan
tool indicates a negative value if there is a vacuum in the fuel tank, and a positive value if there is
pressure in the fuel tank.

Fuel Tank Pressure Sensor

This parameter displays the voltage signal sent to the control module from the sensor used to monitor the
pressure inside the fuel tank. The scan tool will display a low voltage when the pressure in the fuel tank is
high. The scan tool will display a high voltage when the pressure in the fuel tank is low or in a vacuum.

Fuel Tank Rated Capacity

The scan tool displays liters or gallons. This parameter displays the fuel tank capacity as determined by
the calibrations of the vehicle.

Fuel Temperature

This parameter displays the current fuel temperature as calculated by the control module based on input
from the fuel composition sensor. The scan tool will display a higher value at higher fuel temperatures.
The scan tool will display a lower value at lower fuel temperatures.

Fuel Trim Cell

This parameter displays the fuel trim cell as calculated by the control module based on many sensor
inputs. The fuel trim cell indicates which cell is currently active.

Fuel Trim Learn

The scan tool displays Enabled or Disabled. When conditions are appropriate for enabling long term fuel
trim corrections, the scan tool displays Enabled. If the scan tool displays Disabled, then long term fuel
trim will not respond to changes in short term fuel trim.

Generator F-Terminal Signal

This parameter displays the commanded state of the generator by the control module. A high value
indicates a high charging command, and a low value indicates a low charging command.

Generator L-Terminal Signal Command

This parameter displays if the control module is allowing the generator to operate. The scan tool displays
ON if the generator is allowed to operate. The scan tool displays OFF if the control module is disabling
the generator.

HO2S Bank 1 Sensor 1

This parameter displays the voltage from the signal produced by the heated oxygen sensor used to
monitor fuel trim for cylinder bank 1. The scan tool will display a low voltage reading when that cylinder

2004 Hummer H2

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

Hummer H2