Code No. P0122: Throttle Position Sensor (Main) Circuit Low Input

OPERATION

A power voltage of 5 V is applied to the electronic-controlled throttle valve (terminal No. 2) from the engine-ECU (terminal No. 31).
The power voltage is earthed to the engine-ECU (terminal No. 30) from the electronic-controlled throttle valve (terminal No. 4).
The sensor signal is inputted to the engine-ECU (terminal No. 15) from the electronic-controlled throttle valve output terminal (terminal No. 1).

FUNCTION

The throttle position sensor converts the throttle valve position into voltage and inputs it into the engine-ECU.
The engine-ECU controls the throttle valve position.

TROUBLE JUDGMENT

Check Condition

Ignition switch is in "ON" position.

Judgment Criterion

Throttle position sensor (main) output voltage is 0.35 V or less for 0.5 second.

PROBABLE CAUSES

Failed throttle position sensor (main)
Open/short circuit and damage in throttle position sensor circuit or loose connector contact
Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

Refer to Data List Reference Table .

Item No. 13: Throttle position sensor (main)

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Go to Step 2 .

STEP 2. Connector check: A-118 electronic-controlled throttle valve connector

Q. Is the check result normal?

Go to Step 3 .

Repair or replace the connector.

STEP 3. Perform voltage measurement at A-118 electronic-controlled throttle valve connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 2 and earth.

OK: 4.9 - 5.1 V

Q. Is the check result normal?

Go to Step 7 .

Go to Step 4 .

STEP 4. Connector check: A-34 engine-ECU connector

Q. Is the check result normal?

Go to Step 5 .

Repair or replace the connector.

STEP 5. Check harness between A-118 (terminal No. 2) electronic-controlled throttle valve connector and A-34 (terminal No. 31) engine-ECU connector.

Check power supply line for open/short circuit.

Q. Is the check result normal?

Go to Step 6 .

Repair the damaged harness wire.

STEP 6. M.U.T.-III data list

Refer to Data List Reference Table .

Item No. 13: Throttle position sensor (main)

Q. Is the check result normal?

	Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).

	Replace the engine-ECU then perform the variant coding (Refer to GROUP 00 - Precautions Before Service - How to Perform Variant Coding ).

STEP 7. Connector check: A-34 engine-ECU connector

Q. Is the check result normal?

Go to Step 8 .

Repair or replace the connector.

STEP 8. Check harness between A-118 (terminal No. 2) electronic-controlled throttle valve connector and A-34 (terminal No. 31) engine-ECU connector.

Check power supply line for damage.

Q. Is the check result normal?

Go to Step 9 .

Repair the damaged harness wire.

STEP 9. Check harness between A-118 (terminal No. 1) electronic-controlled throttle valve connector and A-34 (terminal No. 15) engine-ECU connector.

Check output line for open/short circuit and damage.

Q. Is the check result normal?

Go to Step 10 .

Repair the damaged harness wire.

STEP 10. Replace the throttle body assembly

After replacing the throttle body assembly re-check the trouble symptoms.

Q. Is the check result normal?

	Check end.

	Replace the engine-ECU then perform the variant coding (Refer to GROUP 00 - Precautions Before Service - How to Perform Variant Coding ).