Code No. P0123: Throttle Position Sensor Circuit High Input

OPERATION

A power voltage of 5 V is applied to the throttle body assembly connector terminal from the engine-ECU connector terminal TPS5.
The power voltage is earthed to the engine-ECU connector terminal TPSE from the throttle body assembly connector terminal.
The sensor signal is inputted to the engine-ECU connector terminal TPSM from the throttle body assembly 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 DPF regeneration is prohibited.
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. Resistance measurement at throttle body assembly connector (TPSE line).

(1)Disconnect the connector, and measure at the wiring harness side.

(2)Measure the resistance between the throttle body assembly connector (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 of open circuit and damage in TPSE line between throttle body assembly connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 4.

	Repair the connector(s) or wiring harness.

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 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.