Hummer H2. Manual - part 1672

DTC P1112 

Circuit Description 

The intake air temperature (IAT) sensor is a variable resistor. The IAT sensor has a signal circuit and a low 
reference circuit. The IAT sensor measures the temperature of the air entering the engine. The powertrain 
control module (PCM) supplies 5 volts to the IAT signal circuit and a ground for the IAT low reference circuit. 
When the IAT sensor is cold, the sensor resistance is high. When the air temperature increases, the sensor 
resistance decreases. With high sensor resistance, the PCM detects a high voltage on the IAT signal circuit. 

Did you find and correct the condition?

Go to Step 8

Go to Step 4

4

Test the IAT signal circuit between the IAT sensor 
and the PCM for an intermittent open. Refer to 
Inducing Intermittent Fault Conditions , Circuit 
Testing and Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 8

Go to Step 5

5

Test the IAT signal circuit between the IAT sensor 
and the PCM for an intermittent short to voltage. 
Refer to Inducing Intermittent Fault Conditions , 
Circuit Testing and Wiring Repairs in Wiring 
Systems. 
Did you find and correct the condition?

-

Go to Step 8

Go to Step 6

6

Test the low reference circuit for an intermittent open. 
Refer to Inducing Intermittent Fault Conditions , 
Circuit Testing and Wiring Repairs in Wiring 
Systems. 
Did you find and correct the condition?

-

Go to Step 8

Go to Step 7

7

Test for an intermittent and for a poor connection at 
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 8

Go to Diagnostic 

Aids

8

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 9

9

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 P0507 (TAC) To DTC U0107) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

With lower sensor resistance, the PCM detects a lower voltage on the IAT signal circuit. If the PCM detects an 
intermittent low IAT signal voltage, indicating a high temperature, DTC P1112 sets. 

Conditions for Running the DTC 

z

DTCs P0112, P0500, P0502, and P0503 are not set.  

z

The engine run time is more than 45 seconds.  

z

The vehicle speed is more than 40 km/h (25 mph).  

z

The ECT sensor parameter is less than 125°C (257°F).  

Conditions for Setting the DTC 

The PCM detects that the IAT sensor parameter is more than 128°C (262°F) intermittently for a calibrated 
amount of time. 

Action Taken When the DTC Sets 

z

The control module stores the DTC information into memory when the diagnostic runs and fails.  

z

The malfunction indicator lamp (MIL) will not illuminate.  

z

The control module records the operating conditions at the time the diagnostic fails. The control module 
stores this information in the Failure Records.  

z

The driver information center, if equipped, may display a message.  

Conditions for Clearing the DTC 

z

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

z

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

z

Clear the DTC with a scan tool.  

Diagnostic Aids 

z

An IAT sensor or PCM which is intermittently shorted, open, or skewed is possible, yet very unlikely.  

z

A skewed sensor could result in poor driveability conditions.  

z

If an intermittent condition is suspected, refer to Intermittent Conditions .  

DTC P1112 

Step

Action

Value

(s)

Yes

No

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

1

Did you perform the Diagnostic System Check-
Engine Controls?

-

Go to Diagnostic 

System Check - 

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0507 (TAC) To DTC U0107) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

DTC P1114 

Circuit Description 

The engine coolant temperature (ECT) sensor is a variable resistor, that measures the temperature of the engine 
coolant. The powertrain control module (PCM) supplies 5 volts to the ECT signal circuit and a ground for the 
ECT low reference circuit. When the ECT is cold, the sensor resistance is high. When the ECT increases, the 
sensor resistance decreases. With high sensor resistance, the PCM detects a high voltage on the ECT signal 
circuit. With lower sensor resistance, the PCM detects a lower voltage on the ECT signal circuit. If the PCM 
detects an excessively low ECT signal voltage, which is a high temperature indication, DTC P1114 sets. 

Conditions for Running the DTC 

The engine run time is more than 10 seconds. 

Conditions for Setting the DTC 

The PCM detects that the ECT sensor parameter is more than 138°C (280°F) intermittently for a calibrated 

Go to Step 2

Engine Controls

2

Observe the DTC information with a scan tool. 
Is DTC P0112 set?

-

Go to DTC 

P0112

Go to Step 3

3

Test for an intermittent and for a poor connection at 
the IAT 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 5

Go to Step 4

4

Test the IAT signal circuit between the IAT sensor 
and the PCM for an intermittent short to ground. Refer 
to Inducing Intermittent Fault Conditions , Circuit 
Testing and Wiring Repairs in Wiring Systems. 
Did you find and correct the condition?

-

Go to Step 5

Go to Diagnostic 

Aids

5

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 6

6

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 P0507 (TAC) To DTC U0107) - 4.8L, 5.3L, and 6.0L - 

Hummer H2

  

amount of time. 

Action Taken When the DTC Sets 

z

The control module stores the DTC information into memory when the diagnostic runs and fails.  

z

The malfunction indicator lamp (MIL) will not illuminate.  

z

The control module records the operating conditions at the time the diagnostic fails. The control module 
stores this information in the Failure Records.  

z

The driver information center, if equipped, may display a message.  

Conditions for Clearing the DTC 

z

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

z

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

z

Clear the DTC with a scan tool.  

Diagnostic Aids 

z

An ECT sensor or PCM which is intermittently shorted, open, or skewed is possible, but very unlikely  

z

An intermittent short to ground in the ECT sensor signal circuit could result in a DTC P1114.  

z

Use the Temperature vs. Resistance Value scale to test the coolant sensor at various temperature levels to 
evaluate the possibility of a skewed sensor. A skewed sensor could result in poor driveability conditions. 
Refer to Temperature vs Resistance .  

z

For an intermittent condition, refer to Intermittent Conditions .  

DTC P1114 

Step

Action

Yes

No

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

1

Did you perform the Diagnostic System Check - Engine 
Controls?

Go to Step 2

Go to Diagnostic 

System Check - 

Engine Controls

2

Observe the DTC information with a scan tool. 
Is DTC P0117 set?

Go to DTC 

P0117

Go to Step 3

3

Observe the engine coolant temperature (ECT) sensor 
parameter with a scan tool while moving the ECT sensor 
connector and the powertrain control module (PCM) 
connector. Refer to Inducing Intermittent Fault Conditions
in Wiring Systems. 
Does the scan tool indicate an abrupt change in value?

Go to Step 6

Go to Step 4

4

Observe the ECT parameter with a scan tool while moving 
the wiring harness at the ECT sensor and the PCM. Refer to 

 

2004 Hummer H2 

2004 ENGINE PERFORMANCE Engine Controls Diagnosis (DTC P0507 (TAC) To DTC U0107) - 4.8L, 5.3L, and 6.0L - 

Hummer H2