P0112

2AZ-FXE ENGINE CONTROL: SFI SYSTEM: P0112,P0113: Intake Air Temperature Circuit Low Input

DESCRIPTION

- The intake air temperature sensor, mounted in the mass air flow meter sub-assembly, monitors the intake air temperature. The intake air temperature sensor has a built-in thermistor with a resistance that varies according to the temperature of the intake air. When the intake air temperature becomes low, the resistance of the thermistor increases. When the temperature becomes high, the resistance drops. These variations in resistance are transmitted to the hybrid vehicle control ECU as voltage changes (see Fig. 1).

- The intake air temperature sensor is powered by a 5 V supply from the THA terminal of the hybrid vehicle control ECU, via resistor R which is located inside the hybrid vehicle control ECU.

- Resistor R and the intake air temperature sensor are connected in series. When the resistance value of the intake air temperature sensor changes, according to changes in the intake air temperature, the voltage at terminal THA also varies. Based on this signal, the hybrid vehicle control ECU increases the fuel injection volume when the engine is cold to improve driveability.

HINT
When either DTC P0112 or P0113 is set, the hybrid vehicle control ECU enters fail-safe mode. During fail-safe mode, the intake air temperature is estimated to be 20°C (68°F) by the hybrid vehicle control ECU. Fail-safe mode continues until a pass condition is detected.

HINT
When any of these DTCs are set, check the intake air temperature by entering the following menus: Powertrain / Engine and ECT / Intake Air.

MONITOR DESCRIPTION

The hybrid vehicle control ECU monitors the sensor voltage and uses this value to calculate the intake air temperature. When the sensor output voltage deviates from the normal operating range, the hybrid vehicle control ECU interprets this as a malfunction in the intake air temperature sensor and sets a DTC.

Example:

If the sensor output voltage is more than 4.91 V for 0.5 seconds or more, the hybrid vehicle control ECU determines that there is an open in the intake air temperature sensor circuit, and sets DTC P0113. Conversely, if the output voltage is less than 0.18 V for 0.5 seconds or more, the hybrid vehicle control ECU determines that there is a short in the sensor circuit, and sets DTC P0112.

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

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

P0112

P0113

COMPONENT OPERATING RANGE

CONFIRMATION DRIVING PATTERN

- Connect the Techstream to the DLC3.

- Turn the power switch on (IG) and turn the Techstream on.

- Clear the DTCs DTC Check / Clear.

- Turn the power switch off and wait for at least 30 seconds.

- Turn the power switch on (IG) and turn the Techstream on.

- Wait 0.5 seconds or more [A].

- Enter the following menus: Powertrain / Engine and ECT / Trouble Codes.

- Read the DTC [B].

HINT
- If a DTC is output, the system is malfunctioning.
- If a DTC is not output, perform the following procedure.
- Enter the following menus: Powertrain / Engine and ECT / Utility / All Readiness.

- Input the DTC: P0112 or P0113.

- Check the DTC judgment result.

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT
Read freeze frame data using the Techstream. The hybrid vehicle control ECU records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction.

PROCEDURE

1. READ VALUE USING TECHSTREAM (INTAKE AIR TEMPERATURE)

(a) Connect the Techstream to the DLC3.

(b) Turn the power switch on (IG).

(c) Turn the Techstream on.

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

(e) Read the value displayed on the Techstream.

OK:

Same as actual intake air temperature.

Result:

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.
C -- CHECK FOR INTERMITTENT PROBLEMS

B -- READ VALUE USING TECHSTREAM (CHECK FOR SHORT IN WIRE HARNESS)
A -- Continue to next step.

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

(a) Confirm a good connection at the mass air flow meter sub-assembly.

Text in Illustration

(b) Disconnect the mass air flow meter sub-assembly connector.

(c) Connect terminals THA and E2 of the mass air flow meter sub-assembly connector on the wire harness side.

(d) Connect the Techstream to the DLC3.

(e) Turn the power switch on (IG).

(f) Turn the Techstream on.

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

(h) Read the value displayed on the Techstream.

Standard Value:

140°C (284°F) or higher

(i) Reconnect the mass air flow meter sub-assembly connector.

NG -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - HYBRID VEHICLE CONTROL ECU)

OK -- REPLACE MASS AIR FLOW METER SUB-ASSEMBLY Removal

3. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - HYBRID VEHICLE CONTROL ECU)

(a) Disconnect the mass air flow meter sub-assembly connector.

(b) Disconnect the hybrid vehicle control ECU connector.

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

Standard Resistance (Check for Open):

(d) Reconnect the mass air flow meter sub-assembly connector.

(e) Reconnect the hybrid vehicle control ECU connector.

NG -- REPAIR OR REPLACE HARNESS OR CONNECTOR

OK -- REPLACE HYBRID VEHICLE CONTROL ECU Removal

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

(a) Disconnect the mass air flow meter sub-assembly connector.

Text in Illustration

(b) Connect the Techstream to the DLC3.

(c) Turn the power switch on (IG).

(d) Turn the Techstream on.

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

(f) Read the value displayed on the Techstream.

Standard Value:

-40°C (-40°F)

(g) Reconnect the mass air flow meter sub-assembly connector.

NG -- CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - HYBRID VEHICLE CONTROL ECU)

OK -- REPLACE MASS AIR FLOW METER SUB-ASSEMBLY Removal

5. CHECK HARNESS AND CONNECTOR (MASS AIR FLOW METER - HYBRID VEHICLE CONTROL ECU)

(a) Disconnect the mass air flow meter sub-assembly connector.

(b) Disconnect the hybrid vehicle control ECU connector.

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

Standard Resistance (Check for Short):