Hummer H2. Manual - part 1628

that the diagnostic runs and does not fail.

A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other
emission related diagnostic.

Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

If a short to a separate 5-volt source occurs, this DTC may set.

After starting the engine, the ECT should rise steadily, then stabilize when the thermostat opens.

Use the Temperature vs. Resistance table in order to test the ECT sensor. A skewed sensor could result in
poor driveability conditions. Refer to Temperature vs Resistance .

If the condition is suspected of being intermittent, refer to Intermittent Conditions .

DTC P0118

Step

Action

Values

Yes

Schematic Reference: Engine Controls Schematics
Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or
Engine Controls Connector End Views

Did you perform the Diagnostic System Check-
Engine Controls?

Go to Step 2

Go to Diagnostic

System Check -

Engine Controls

Observe the ECT sensor parameter with a scan
tool.
Is the ECT sensor parameter less than the specified
value?

-38°C (-

36°F)

Go to Step 4

Go to Step 3

1. Observe the Freeze Frame/Failure Records

for this DTC.

2. Turn OFF the ignition for 30 seconds.

3. Start the engine.

4. Operate the vehicle within the Conditions for

Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/Failure
Records.

Did the DTC fail this ignition?

Go to Step 4

Go to Diagnostic

Aids

1. Disconnect the ECT sensor.

2. Measure the voltage from the signal circuit

of the ECT sensor to a good ground with a
DMM. Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.

5.2 V

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

Is the voltage more than the specified value?

Go to Step 5

Go to Step 6

Test the ECT signal circuit for a short to voltage.
Refer to Circuit Testing and Wiring Repairs in
Wiring Systems.Did you find and correct the
condition?

IMPORTANT:

If a short to voltage occurs, the ECT sensor may
be damaged.

Go to Step 15

Go to Step 12

1. Connect a 3-amp fused jumper between the

signal circuit of the ECT sensor and the low
reference circuit. Refer to Using Fused
Jumper Wires in Wiring Systems.

2. Observe the ECT sensor parameter with the

scan tool.

Is the ECT sensor parameter more than the
specified value?

138°C

(280°F)

Go to Step 10

Go to Step 7

1. Connect a 3-amp fused jumper between the

signal circuit of the ECT sensor and a good
ground.

2. Observe the ECT sensor parameter with a

scan tool.

Is the ECT sensor parameter more than the
specified value?

138°C

(280°F)

Go to Step 9

Go to Step 8

Test the signal circuit of the ECT sensor for a high
resistance or an open. Refer to Circuit Testing and
Wiring Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 15

Go to Step 12

Test the low reference circuit of the ECT sensor for
a high resistance or an open. Refer to Circuit
Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 15

Go to Step 12

Test the ECT signal circuit for a short to any 5-volt
reference circuit. Refer to Circuit Testing and
Wiring Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 15

Go to Step 11

Test for an intermittent and for a poor connection at
the ECT sensor. 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 15

Go to Step 13

Test for an intermittent and for a poor connection at

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

DTC P0120

Circuit Description

The throttle position (TP) sensor 1 is a potentiometer type sensor with the following circuits:

A 5-volt reference circuit

A low reference circuit

A signal circuit

The TP sensor is used to determine the throttle plate angle for various engine management systems. The control
module provides the TP sensor a 5-volt reference circuit and a low reference circuit. The TP sensor then
provides the control module a signal voltage proportional to throttle plate movement. TP sensor 1 signal voltage
is low at closed throttle and increases as the throttle opens. When the control module detects that the TP sensor
1 signal or TP sensor 5-volt reference voltage is outside the predetermined range, this DTC sets.

Conditions for Running the DTC

DTCs P2108 or U0107 are not set.

The ignition switch is in the Crank or Run position.

the PCM. 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 15

Go to Step 14

Replace the ECT sensor. Refer to Engine Coolant
Temperature (ECT) Sensor Replacement .
Did you complete the replacement?

Go to Step 15

Replace the PCM. Refer to Powertrain Control
Module (PCM) Replacement .
Did you complete the replacement?

Go to Step 15

1. Clear the DTCs with a scan tool.

2. Turn OFF the ignition for 30 seconds.

3. Start the engine.

4. Operate the vehicle within the Conditions for

Running the DTC. You may also operate the
vehicle within the conditions that you
observed from the Freeze Frame/Failure
Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 16

Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?

Go to Diagnostic

Trouble Code

(DTC) List

System OK

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

The ignition voltage is more than 5.23 volts.

Conditions for Setting the DTC

The TP sensor 1 signal voltage is less than 0.37 volt or more than 4.51 volts.

The above condition is present for more than 1 second.

Action Taken When the DTC Sets

The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.

The control module records the operating conditions at the time the diagnostic fails. The control module
stores this information in the Freeze Frame and/or the Failure Records.

The control module commands the TAC system to operate in the Reduced Engine Power mode.

A message center or an indicator displays Reduced Engine Power.

Under certain conditions the control module commands the engine OFF.

Conditions for Clearing the MIL/DTC

The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles
that the diagnostic runs and does not fail.

A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other
emission related diagnostic.

Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

Inspect the TAC module connectors for signs of water intrusion. When this occurs, multiple DTCs could
be set with no circuit or component conditions found during diagnostic testing.

When the TAC module detects a condition within the TAC system, more than one TAC system related
DTC may set. This is due to the many redundant tests run continuously on this system. Locating and
repairing one individual condition may correct more than one DTC. Disconnecting components during
testing may set additional DTCs. Keep this in mind when reviewing the stored information, Capture Info.

If this DTC is determined to be intermittent, refer to Intermittent Conditions .

Test Description

The number below refers to the step number on the diagnostic table.

33: When the TAC module detects a condition within the TAC system, more than one TAC system
related DTC may set. This is due to the many redundant tests run continuously on this system. Locating
and repairing one individual condition may correct more than one DTC. Disconnecting components
during testing may set additional DTCs. Keep this in mind when reviewing the stored information,
Capture Info.

2004 Hummer H2

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0068 To DTC P0141/P0161) - 4.8L, 5.3L, and 6.0L -

Hummer H2

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