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. 5) from the engine-ECU (terminal No. 12).
The power voltage is earthed to the engine-ECU (terminal No. 13) from the electronic-controlled throttle valve (terminal No. 3).
The sensor signal is inputted to the engine-ECU (terminal No. 10) 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 opening angle.

TROUBLE JUDGMENT

Check Condition

Ignition switch is "ON" position.

Judgement Criterion

Throttle position sensor (main) output voltage is less than 0.2 V.

FAIL-SAFE AND BACKUP FUNCTION

Throttle opening degree is restricted.
Throttle opening degree position is in default position if throttle position sensor (sub) fails.

PROBABLE CAUSES

Failed throttle position sensor (main)
Short circuit or harness damage in throttle position sensor (main) 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 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: B-11 electronic-controlled throttle valve connector and B-08 engine-ECU connector

Q. Are the check results normal?

	Go to Step 3.

	Repair or replace the connector.

STEP 3. Check harness between B-11 (terminal No. 5) electronic-controlled throttle valve connector and B-08 (terminal No. 12) engine-ECU connector.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 4.

	Repair the damaged harness wire.

STEP 4. Check harness between B-11 (terminal No. 4) electronic-controlled throttle valve connector and B-08 (terminal No. 10) engine-ECU connector.

Check output line for short circuit.

Q. Is the check result normal?

	Go to Step 5.

	Repair the damaged harness wire.

STEP 5. M.U.T.-III data list

Refer to Data List Reference Table .

Item 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 6.

STEP 6. Replace the electronic-controlled throttle valve

After replacing the electronic-controlled throttle valve, reconfirm whether the diagnosis code is set.

Q. Is the diagnosis code set?

	Replace the engine-ECU.

	Check end.

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