Code No. P0123: Throttle Position Sensor Circuit High Input

OPERATION

A power voltage of 5 V is applied to the electronic-controlled throttle valve connector terminal from the engine-ECU connector terminal TPS5.
The power voltage is earthed to the engine-ECU connector terminal TPSE from the electronic-controlled throttle valve connector terminal.
The sensor signal is inputted to the engine-ECU connector terminal TPSM from the electronic-controlled throttle valve output terminal.

FUNCTION

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

TROUBLE JUDGEMENT

Check Conditions

Battery positive voltage is 8 - 16 V
2 seconds later after the ignition switch has been in "ON" position or the engine has started up

Judgement Criterion

The throttle position sensor output voltage is 4.85 V or more.

FAIL-SAFE AND BACKUP FUNCTION

The throttle valve is opened. (Electrical discontinuity)
The EGR control is stopped (fully closed).

PROBABLE CAUSES

Failed throttle position sensor
Open circuit or harness 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 45: Throttle position sensor

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. Perform resistance measurement at electronic-controlled throttle valve connector.

Disconnect connector, and measure at harness side.
Resistance between terminal engine-ECU TPSE line and body earth.

OK: Continuity (2 Ω or less)

Q. Is the check result normal?

	Go to Step 5.

	Go to Step 3.

STEP 3. Check harness between electronic-controlled throttle valve connector terminal and engine-ECU connector terminal TPSE.

Check earthing line for open circuit and damage.

Q. Is the check result normal?

	Go to Step 4.

	Repair or replace the connector, or repair the damaged harness wire.

STEP 4. M.U.T.-III data list

Refer to Data List Reference Table .

Item 45: Throttle position sensor

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.

STEP 5. Replace the electronic-controlled throttle valve

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

Q. Is the check result normal?

	Check end.

	Replace the engine-ECU.