GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2001 🢒 Tahoe - 2WD 🢒 Engine 🢒 Engine Controls - 8.1L 🢒 DTC P0113

Circuit Description

The intake air temperature (IAT) sensor contains a semiconductor device which changes the resistance based on the temperature. The IAT sensor is located within the mass air flow (MAF) sensor. The IAT sensor has a signal circuit and a low reference circuit. The powertrain control module (PCM) applies 5 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 resistance is high. The PCM signal voltage is only pulled down a small amount through the low reference circuit, therefore, the PCM senses a high signal voltage. 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.

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, P0500, P0502, or P0503 are not set.
    • The engine coolant temperature (ECT) is more than 0°C (32°F).
    • The vehicle speed is less than 11 km/h (7 mph).
    • The MAF is less than 15 g/s.
    • The engine run time is more than 100 seconds

Conditions for Setting the DTC

The IAT is less than -35°C (-31°F) for more than 5 seconds.

Action Taken When the DTC Sets
    • The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
    • The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.

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
    •  If the engine has sat overnight, the ECT and the IAT values should display within a few degrees of each other. If the temperatures are not within 3°C (5°F), refer to Temperature Versus Resistance .
    •  If you determine that the DTC occurs intermittently, performing the DTC P1111 diagnostic table may isolate the cause of the fault.

For an intermittent, refer to Intermittent Conditions .

Test Description

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

  1. This step determines if the malfunction is present. Using this kit prevents damage to the harness connector terminals.

  2. Using the Freeze Frame/Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame/Failure Records data can help determine how many miles since the DTC set. The Fail Counter and the Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass or a fail. Operate the vehicle within the same Freeze Frame conditions such as RPM, load, vehicle speed, temperature, etc. that you observed. This will isolate when the DTC failed.

  3. An intake air temperature above 139°C (282°F) indicates the PCM and IAT sensor wiring is OK.

    4.

  4. An intake air temperature above 139°C (282°F) indicates the PCM and IAT sensor signal circuit is OK.

    5.

  5. Disconnecting the PCM allows using the DMM in order to test for continuity of the circuits. This aids in locating an open or a shorted circuit.

    6.

  6. Disconnecting the PCM allows using the DMM in order to test for a short to voltage.

    7.

  7. Disconnecting the PCM allows using the DMM in order to test for continuity of the circuits. This aids in locating an open or a shorted circuit. Probe one lead to the IAT sensor signal circuit and probe the other lead to each terminal at the PCM harness connectors.

    8.

  8. Inspect for proper terminal tension and connections at the PCM harness before replacing the PCM.

Step

Action

Values

Yes

No

Schematic Reference: Engine Controls Schematics

1

Did you perform the Diagnostic System Check-Engine Controls?

--

Go to Step 2

Go to Diagnostic System Check - Engine Controls

2

  1. Install a scan tool.
  2. Turn ON the ignition, with the engine OFF.
  3. Monitor the IAT sensor display on the Engine 1 Data List of the scan tool.

Is the IAT sensor at the specified value?

-39°C (-38°F)

Go to Step 3

Go to Step 4

3

Are DTCs P1635 and P1639 also set?

--

Go to Step 14

Go to Step 5

4

  1. Turn ON the ignition, with the engine OFF.
  2. Review the Freeze Frame/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/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 5

Go to Diagnostic Aids

5

  1. Disconnect the MAF/IAT sensor electrical connector.
  2. Jumper the IAT sensor signal circuit and low reference circuit together.
  3. Observe the IAT parameter on the scan tool.

Is the IAT sensor at the specified value?

140°C (284°F)

Go to Step 8

Go to Step 6

6

Jumper the IAT sensor signal circuit to a known good ground.

Is the IAT sensor at the specified value?

140°C (284°F)

Go to Step 10

Go to Step 7

7

  1. Turn OFF the ignition.
  2. Disconnect the PCM. Refer to Powertrain Control Module Replacement .
  3. Test the IAT sensor signal circuit for an open. Refer to Testing for Continuity in Wiring Systems.

Is the IAT sensor signal circuit open?

--

Go to Step 11

Go to Step 16

8

  1. Turn OFF the ignition.
  2. Remove the jumper harness from the IAT sensor harness connector.
  3. Disconnect the PCM. Refer to Powertrain Control Module Replacement .
  4. Turn ON the ignition, with the engine OFF.
  5. Probe the IAT signal circuit at the PCM harness connector using the DMM connected to ground. Refer to Probing Electrical Connectors in Wiring Systems.

Does the DMM display a voltage?

--

Go to Step 14

Go to Step 9

9

Test for continuity from the IAT signal circuit to all other PCM circuits at both the PCM harness connectors using the DMM. Refer to Testing for Continuity in Wiring Systems.

Does the DMM display continuity within the specified range from the IAT sensor signal circuit to any other PCM circuit?

0-2 ohms

Go to Step 15

Go to Step 12

10
  1. Turn OFF the ignition.
  2. Disconnect the PCM. Refer to Powertrain Control Module Replacement .
  3. Inspect the IAT sensor low reference circuit for an open. Refer to Testing for Continuity in Wiring Systems.

Is the IAT sensor ground circuit open?

--

Go to Step 13

Go to Step 16

11

Repair the IAT sensor signal circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 18

--

12

Replace the IAT sensor. Refer to Mass Airflow Sensor/Intake Air Temperature Sensor Replacement .

Is the action complete?

--

Go to Step 18

--

13

Repair the IAT sensor low reference circuit. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 18

--

14

Repair the IAT sensor signal circuit for a short to voltage. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 18

--

15

Repair the short between the IAT sensor signal circuit and the PCM circuit that had continuity. Refer to Wiring Repairs in Wiring Systems.

Is the action complete?

--

Go to Step 18

--

16

  1. Inspect the PCM harness connector for poor connections. Refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems.
  2. If you find a poor connection, repair the condition as necessary. Refer to Connector Repairs in Wiring Systems.

Did you find and repair the condition?

--

Go to Step 18

Go to Step 17

17

Replace the PCM. Refer to Powertrain Control Module Replacement .

Is the action complete?

--

Go to Step 18

--

18
  1. Use the scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC run and pass?

--

Go to Step 19

Go to Step 2

19

With a scan tool, observe the stored information, Capture Info.

Does the scan tool display any DTCs that you have not diagnosed?

--

Go to Diagnostic Trouble Code (DTC) List

System OK