DTC P0112 Intake Air Temperature Sensor Circuit Low (4JJ3 without DPD)

1. Engine control system check

Refer to "51.Engine Control 1A.Troubleshooting(4JJ3 without DPD) Diagnostic system check-engine controls".

2. IAT sensor signal voltage check

1) Observe the Intake Air Temperature (IAT) Sensor parameter on the scan tool. Is the Intake Air Temperature (IAT) Sensor parameter less than or equal to the specified value?

Value: 0.1 V

Yes

=>Go to IAT sensor signal output voltage check.

No

Go to Intermittent conditions of engine.

Refer to "202.Engine 15D.Symptom(4JJ3 without DPD) intermittent conditions of engine".

3. IAT sensor signal output voltage check

1) Turn OFF the ignition switch.

2) Disconnect the MAF and IAT sensor harness connector (C39).

Refer to "LHD Engine Control (4JJ3 without DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Engine Control (4JJ3 without DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

3) Turn ON the ignition switch.

4) Observe the Intake Air Temperature (IAT) Sensor parameter on the scan tool. Is the Intake Air Temperature (IAT) Sensor parameter more than or equal to the specified value?

Value: 4.5 V

Yes

Replace the MAF and IAT sensor.

Refer to "1.Engine 1Z.Engine Electrical Control(4JJ3 without DPD) MAF and IAT sensor removal".

Refer to "1.Engine 1Z.Engine Electrical Control(4JJ3 without DPD) MAF and IAT sensor installation".

=>Go to Repair verification.

No

=>Go to Inspection for short to ground in IAT sensor signal circuit.

4. Inspection for short to ground in IAT sensor signal circuit

1) Inspect the IAT sensor signal circuit between the ECM (pin 33 of C9) and the MAF and IAT sensor (pin 4 of C39) for the following. Is the result normal?

Refer to "LHD Engine Control (4JJ3 without DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Engine Control (4JJ3 without DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to ECM harness connector inspection.

No

Repair the circuit as necessary.

=>Go to Repair verification.

5. ECM harness connector inspection

1) Inspect for poor connections at the ECM harness connector (pins 17 and 33 of C9). Is the connection status normal?

Refer to "LHD Engine Control (4JJ3 without DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Refer to "RHD Engine Control (4JJ3 without DPD)" in the ETM (wiring diagram). (Open using the ETM viewer.).

Yes

=>Go to ECM replacement.

No

Repair the connections as necessary.

=>Go to Repair verification.

6. ECM replacement

Refer to "1.Engine 1Z.Engine Electrical Control(4JJ3 without DPD) ECM removal".

Refer to "1.Engine 1Z.Engine Electrical Control(4JJ3 without DPD) ECM installation".

Refer to "1.Engine 1Z.Engine Electrical Control(4JJ3 without DPD) ECM setting".

Procedure completion

=>Go to Repair verification.

7. Repair verification

1) Clear the DTC with a scan tool.

2) Turn OFF the ignition switch for 1 minute or more.

3) Start the engine.

4) Operate the vehicle under the conditions for running the DTC.

5) Observe the DTC information with a scan tool.