Hummer H2. Manual - part 1573

DTC P1115 

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 high signal voltage, which is a low temperature indication, DTC P1115 sets. 

Conditions for Running the DTC 

Inducing Intermittent Fault Conditions in Wiring Systems.
Does the scan tool indicate an abrupt change in value?

Go to Step 7

Go to Step 5

5

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 2

System OK

6

Repair the ECT connector or the terminal as necessary. Refer 
to Connector Repairs in Wiring Systems. 
Did you complete the repair?

Go to Step 8

-

7

Repair the ECT wiring or the wiring harness as necessary. 
Refer to Wiring Repairs in Wiring Systems. 
Did you complete the repair?

Go to Step 8

-

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

  

The engine run time is more than 60 seconds.

Conditions for Setting the DTC 

The PCM detects that the ECT sensor parameter is less than -38°C (-36°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 ECT sensor or PCM which is intermittently shorted, open, or skewed is possible, but very unlikely.  

z

An intermittent open or a short to voltage in the ECT sensor signal circuit could result in DTC P1115 
setting. Refer to Intermittent Conditions .  

z

Use the Temperature vs. Resistance Value table 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 .  

DTC P1115 

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 P0118 set?

Go to DTC 

P0118

Go to Step 3

1. Turn OFF the engine.  

2. Turn ON the ignition, with the engine OFF.  

3. Observe the engine coolant temperature (ECT) sensor 

 

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 P1125 

Circuit Description 

3

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 
Inducing Intermittent Fault Conditions in Wiring Systems.
Does the scan tool indicate an abrupt change in value?

Go to Step 7

Go to Step 5

5

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 2

System OK

6

Repair the ECT connector or the terminal as necessary. Refer 
to Connector Repairs in Wiring Systems. 
Did you complete the repair?

Go to Step 8

-

7

Repair the wiring harness or the wiring as necessary. Refer to 
Wiring Repairs in Wiring Systems. 
Did you complete the repair?

Go to Step 8

-

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

  

The accelerator pedal position (APP) sensor 1 and the APP sensor 2 are potentiometer type sensors, each with 
the following circuits: 

z

A 5-volt reference circuit  

z

A low reference circuit  

z

A signal circuit  

The control module provides the APP sensors with a 5-volt reference circuit and a low reference circuit. The 
APP sensors then provide the control module signal voltages proportional to pedal movement. The APP sensor 
1 signal voltage is low at rest and increases as the pedal is depressed. The APP sensor 2 signal voltage is low at 
rest and increases as the pedal is depressed. When the control module detects that the APP sensor 1 and the APP 
sensor 2 signal circuits are out of correlation with each other, DTC P1125 sets. 

Conditions for Running the DTC 

z

DTC P1518, P2108 or U0107 is not set.  

z

The ignition is in the Crank or Run position.  

z

The ignition voltage is more than 5.23 volts.  

z

The communication between the throttle actuator control (TAC) module and the powertrain control 
module (PCM) must be valid.  

Conditions for Setting the DTC 

The PCM detects that the difference between APP sensor 1 and APP sensor 2 is more than the predicted value. 

Action Taken When the DTC Sets 

z

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

z

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.  

z

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

z

A message center or an indicator displays Reduced Engine Power.  

z

Under certain conditions the control module commands the engine OFF.  

Conditions for Clearing the MIL/DTC 

z

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

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 
emission related diagnostic.  

z

Clear the MIL and the DTC with a scan tool.  

DTC P1125 

 

2004 Hummer H2 

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

Hummer H2