Code No. P0123: Throttle Position Sensor (Main) Circuit High Input <3A9>

OPERATION

A power voltage of 5 V is applied to the electronic-controlled throttle valve (terminal No. 5) 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. 3).
The sensor signal is inputted to the engine-ECU (terminal No. 15) from the electronic-controlled throttle valve output terminal (terminal No. 4).

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 4.8 V or more for 0.5 second.

PROBABLE CAUSES

Failed throttle position sensor (main)
Open throttle position sensor (main) circuit, harness damage, or connector damage
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. 5 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-08 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. 5) electronic-controlled throttle valve connector and A-08 (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. Perform resistance measurement at A-118 electronic-controlled throttle valve connector.

Disconnect connector, and measure at harness side.
Resistance between terminal No. 3 and earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

Go to Step 10 .

Go to Step 8 .

STEP 8. Connector check: A-08 engine-ECU connector

Q. Is the check result normal?

Go to Step 9 .

Repair or replace the connector.

STEP 9. Check harness between A-118 (terminal No. 3) electronic-controlled throttle valve connector and A-08 (terminal No. 30) engine-ECU connector

Check earthing line for open circuit and damage.

Q. Is the check result normal?

Go to Step 6 .

Repair the damaged harness wire.

STEP 10. Connector check: A-08 engine-ECU connector

Q. Is the check result normal?

Go to Step 11 .

Repair or replace the connector.

STEP 11. Check harness between A-118 (terminal No. 5) electronic-controlled throttle valve connector and A-08 (terminal No. 31) engine-ECU connector.

Check power supply line for damage.

Q. Is the check result normal?

Go to Step 12 .

Repair the damaged harness wire.

STEP 12. Check harness between A-118 (terminal No. 4) electronic-controlled throttle valve connector and A-08 (terminal No. 15) engine-ECU connector.

Check output line for open/short circuit and damage.

Q. Is the check result normal?

Go to Step 13 .

Repair the damaged harness wire.

STEP 13. 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 14 .

STEP 14. Replace the throttle body assembly

After replacing the throttle body assembly, reconfirm whether the diagnosis code is set.

Q. Is the diagnosis code set?

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

	Check end.