Toyota Tundra Service Manual: Intake Air Temperature Circuit Low Input (P0112,P0113)

Toyota Tundra Service Manual / Engine, Hybrid System / 1ur-fe Engine Control / Sfi System / Intake Air Temperature Circuit Low Input (P0112,P0113)

DESCRIPTION

  • The Intake Air Temperature (IAT) sensor, mounted on the Mass Air Flow (MAF) meter, monitors the IAT. The IAT sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the IAT is low, the resistance of the thermistor increases. When the temperature is high, the resistance drops. These variations in resistance are transmitted to the ECM as voltage changes (see Fig. 1).
  • The IAT sensor is powered by a 5 V supply from the THA terminal of the ECM, via resistor R.
  • Resistor R and the IAT sensor are connected in series. When the resistance value of the IAT sensor changes, according to changes in the IAT, the voltage at terminal THA also varies. Based on this signal, the ECM increases the fuel injection volume when the engine is cold to improve driveability.

    HINT:

    When DTC P0112 or P0113 is stored, the ECM enters fail-safe mode. During fail-safe mode, the IAT is estimated to be 20°C (68°F) by the ECM. Fail-safe mode continues until a pass condition is detected.

DTC No.

DTC Detection Condition

Trouble Area

P0112

Short in IAT sensor circuit for 0.5 seconds

(1 trip detection logic)

  • Short in IAT sensor circuit
  • IAT sensor (built into MAF meter)
  • ECM

P0113

Open in IAT sensor circuit for 0.5 seconds

(1 trip detection logic)

  • Open in IAT sensor circuit
  • IAT sensor (built into MAF meter)
  • ECM

HINT:

When either of these DTCs is stored, check the IAT by entering the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

Temperature Displayed

Malfunction

-40°C (-40°F)

Open circuit

140°C (284°F) or higher

Short circuit

MONITOR DESCRIPTION

The ECM monitors the sensor voltage and uses this value to calculate the IAT. When the sensor output voltage deviates from the normal operating range, the ECM interprets this as a malfunction in the IAT sensor and stores a DTC.

Example:

If the sensor output voltage is more than 4.91 V for 0.5 seconds or more, the ECM determines that there is an open in the IAT sensor circuit, and stores DTC P0113. Conversely, if the output voltage is less than 0.18 V for 0.5 seconds or more, the ECM determines that there is a short in the sensor circuit, and stores DTC P0112.

If the malfunction is not repaired successfully, a DTC is stored 0.5 seconds after the engine is next started.

MONITOR STRATEGY

Related DTCs

P0112: IAT sensor range check (Low voltage)

P0113: IAT sensor range check (High voltage)

Required Sensors/Components (Main)

IAT sensor

Required Sensors/Components (Related)

-

Frequency of Operation

Continuous

Duration

0.5 seconds

MIL Operation

Immediate

Sequence of Operation

None

TYPICAL ENABLING CONDITIONS

Monitor runs whenever following DTCs not present

None

Battery voltage

8 V or more

Ignition switch

ON

Starter

OFF

TYPICAL MALFUNCTION THRESHOLDS

P0112

IAT sensor voltage [IAT]

Less than 0.18 V [More than 128°C (262.4°F)]

P0113

IAT sensor voltage [IAT]

More than 4.91 V [Less than -55°C (-67°F)]

COMPONENT OPERATING RANGE

IAT sensor voltage [IAT]

0.18 to 4.91 V [-55 to 128°C (-67 to 262.4°F)]

CONFIRMATION DRIVING PATTERN

  1. Connect the Techstream to the DLC3.
  2. Turn the ignition switch to ON and turn the Techstream on.
  3. Clear DTCs (even if no DTCs are stored, perform the clear DTC operation).
  4. Turn the ignition switch off and wait for at least 30 seconds.
  5. Turn the ignition switch to ON and turn the Techstream on.
  6. Wait 0.5 seconds or more.
  7. Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.
  8. Read the pending DTCs.

    HINT:

    • If a pending DTC is output, the system is malfunctioning.
    • If a pending DTC is not output, perform the following procedure.
  9. Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.
  10. Input the DTC: P0112 or P0113.
  11. Check the DTC judgment result.

    Tester Display

    Description

    NORMAL

    • DTC judgment completed
    • System normal

    ABNORMAL

    • DTC judgment completed
    • System abnormal

    INCOMPLETE

    • DTC judgment not completed
    • Perform driving pattern after confirming DTC enabling conditions

    N/A

    • Unable to perform DTC judgment
    • Number of DTCs which do not fulfill DTC preconditions has reached ECU memory limit
  12. If the test result is INCOMPLETE or N/A and no pending DTC is output, perform a universal trip and check for permanent DTCs (See page ).

    HINT:

    • If a permanent DTC is output, the system is malfunctioning.
    • If no permanent DTC is output, the system is normal.

WIRING DIAGRAM

CAUTION / NOTICE / HINT

HINT:

Read freeze frame data using the Techstream. Freeze frame data records the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data from the time the malfunction occurred.

PROCEDURE

1.

READ VALUE USING TECHSTREAM (INTAKE AIR TEMPERATURE)

(a) Connect the Techstream to the DLC3.

(b) Turn the ignition switch to ON.

(c) Turn the Techstream on.

(d) Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

(e) Read the value displayed on the Techstream.

Standard:

Same as actual Intake Air Temperature (IAT).

Result

Result

Proceed to

-40°C (-40°F)

A

140°C (284°F) or higher

B

Same as actual IAT

C

HINT:

  • If there is an open circuit, the Techstream indicates -40°C (-40°F).
  • If there is a short circuit, the Techstream indicates 140°C (284°F) or higher.
B

GO TO STEP 4

C

CHECK FOR INTERMITTENT PROBLEMS

A

2.

READ VALUE USING TECHSTREAM (CHECK FOR OPEN IN WIRE HARNESS)

(a) Disconnect the MAF meter connector.

(b) Connect terminals 4 (THA) and 5 (E2) of the MAF meter wire harness side connector.

(c) Connect the Techstream to the DLC3.

(d) Turn the ignition switch to ON.

(e) Turn the Techstream on.

(f) Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

(g) Read the value displayed on the Techstream.

Standard value:

140°C (284°F) or higher

HINT:

Perform "Inspection After Repair" after replacing the mass air flow meter (See page ).

OK

CONFIRM GOOD CONNECTION TO SENSOR. IF OK, REPLACE MASS AIR FLOW METER

NG

3.

CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

(a) Disconnect the MAF meter connector.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

D7-4 (THA) - D74-73 (THA)

Always

Below 1 Ω

D7-5 (E2) - D74-98 (E2)

Always

Below 1 Ω

OK

CONFIRM GOOD CONNECTION TO ECM. IF OK, REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

4.

READ VALUE USING TECHSTREAM (CHECK FOR SHORT IN WIRE HARNESS)

(a) Disconnect the MAF meter connector.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Turn the Techstream on.

(e) Enter the following menus: Powertrain / Engine and ECT / Data List / Intake Air.

(f) Read the value displayed on the Techstream.

Standard value:

-40°C (-40°F)

HINT:

Perform "Inspection After Repair" after replacing the mass air flow meter (See page ).

OK

REPLACE MASS AIR FLOW METER

NG

5.

CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - ECM)

(a) Disconnect the MAF meter connector.

(b) Disconnect the ECM connector.

(c) Measure the resistance according to the value(s) in the table below.

Standard Resistance:

Tester Connection

Condition

Specified Condition

D7-4 (THA) or D74-73 (THA) - Body ground

Always

10 kΩ or higher

OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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