DTC P1111 Intake Air Temperature (IAT) Sensor Circuit Intermittent High Voltage. Oldsmobile Shelby Series 1 1999

For 1990-2009 cars
Engine Controls Components
Information Sensors
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice
Handling ESD Sensitive Parts Notice

### Circuit Description

The intake air temperature (IAT) sensor contains a semiconductor device which changes the resistance based on the temperature (a thermistor). The IAT sensor is located within the mass air flow (MAF) sensor. The IAT sensor has a signal circuit and a ground circuit. The powertrain control module (PCM) applies 5.0 volts on the signal circuit to the sensor. The PCM monitors the changes in this voltage caused by changes in the resistance of the sensor in order to determine intake air temperature.

When the intake air is cold, the sensor (thermistor) resistance is high. The PCMs signal voltage is only pulled down a small amount through the sensor to a ground, therefore, the PCM senses a high signal voltage or low temperature. When the intake air is warm, the sensor resistance is low. The signal voltage is pulled down a greater amount, therefore, the PCM senses a low signal voltage or high temperature.

When the PCM senses a signal voltage higher than the normal operating range of the sensor, this diagnostic trouble code (DTC) sets.

### Conditions for Running the DTC

• | DTCs P0102, P0103, P0117, P0118 and P0500 are not set.

• | The engine run time is more than 100 seconds.

• | The engine coolant temperature is more than 0°C (32°F).

• | The vehicle speed is less than 11 km/h (7 mph).

• | The mass air flow is less than 15 g/s.

### Conditions for Setting the DTC

• | The intake air temperature is less than -35°C (-31°F).

• | The intermittent condition exists for a total of 1.0 second during a 20.0 second time period.

### Action Taken When the DTC Sets

• | The powertrain control module (PCM) stores the DTC information into memory when the diagnostic runs and fails.

• | The malfunction indicator lamp (MIL) will not illuminate.

• | The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Failure Records.

### Conditions for Clearing the DTC

• | A History DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic.

• | A last test failed, or current DTC, will clear when the diagnostic runs and does not fail.

• | Use a scan tool in order to clear the DTC.

### Diagnostic Aids

Important: Remove any debris from the PCM connector surfaces before servicing the PCM. Inspect the PCM connector gaskets when diagnosing or replacing the PCM. Ensure that the gaskets are installed correctly. The gaskets prevent water intrusion into the PCM.

If the engine has sat overnight, the engine coolant temperature and intake air temperature values should display within a few degrees of each other. If the temperatures are not within 3°C (5°F), refer to Temperature vs Resistance .

For an intermittent, refer to Symptoms .

### Test Description

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

1. If DTC P0113 failed this ignition, this indicates a hard failure is present. When a hard failure is present, both the hard and intermittent DTCs set.

2. When moving related connectors, visually and physically inspect connectors for the following:

• | Poor mating of the connector halves or a terminal not fully seated or backed out in the connector body

• | Improperly formed or damaged terminals -- Carefully reform or replace all connector terminals in the related circuits in order to insure proper terminal contact tension.

• | Poor terminal to wire connection -- Inspect for poor crimps, crimping over wire insulation rather than the wire.

• | Dirt or corrosion on the terminals -- Inspect the connector seals for being there and for being damaged.

3. When moving the related wiring harnesses, visually and physically inspect the wiring for the following:

• | Wire insulation that is rubbed through, causing an intermittent short

• | Wiring broken inside the insulation

4. Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same Freeze Frame conditions, such as RPM, load, vehicle speed, temperature, that you observed. This will isolate when the DTC failed. For any test that requires probing the PCM or component harness connectors, use the J 35616 connector test adapter kit . Using this kit prevents any damage to the harness connector terminals.

Step | Action | Values | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Powertrain On-Board Diagnostic (OBD) System Check? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check

2

1. Install a scan tool.
2. Idle the engine.
3. Monitor the DTC Information option using the scan tool.

Did DTC P0113 Fail This Ignition?

--

Go to DTC P0113 Intake Air Temperature (IAT) Sensor Circuit High Voltage

Go to Step 3

3

1. Turn ON the ignition leaving the engine OFF.
2. Observe the affected sensor value on a scan tool while moving the related harness connectors at the component and the PCM.

Does the sensor value change abruptly while a related connector is being moved?

--

Go to Step 6

Go to Step 4

4 | Observe the affected sensor value on a scan tool while moving the related wiring harnesses. Does the sensor value change abruptly while moving the related electrical harnesses? | -- | Go to Step 7 | Go to Step 5

5

1. Turn ON the ignition leaving the engine OFF.
2. Review the Freeze Frame and/or Failure Records data for this DTC and observe the parameters.
3. Turn OFF the ignition for 15 seconds.
4. Start the engine.
5. Operate the vehicle within the conditions required for this diagnostic to run, and as close to the conditions recorded in the Freeze Frame and Failure Records as possible. Special operating conditions that you need to meet before the PCM will run this diagnostic, where applicable, are listed in Conditions for Running the DTC.
6. Select the Diagnostic Trouble Code (DTC) option, the Specific DTC option, then enter the DTC number using the scan tool.

Does the scan tool indicate that this diagnostic failed this ignition?

--

Go to Step 8

Go to Diagnostic Aids

6 | Repair the damaged connectors and terminals. Refer to Connector Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 9 | --
7 | Repair the circuit as necessary. Refer to Wiring Repairs in Wiring Systems. Is the action complete? | -- | Go to Step 9 | --

8

1. Re-inspect all the related circuits and the connectors.
2. Replace the sensor or component if all the circuits have been tested thoroughly and no faults can be found.

Is the action complete?

--

Go to Step 9

--

9

1. Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool.
2. Idle the engine at the normal operating temperature.
3. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool.
4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable.

Does the scan tool indicate that this test ran and passed?

--

Go to Step 10

Go to Step 2

10 | Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed? | -- | Go to the applicable DTC table | System OK