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 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.
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 controls the throttle valve opening angle.

TROUBLE JUDGEMENT

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)
Open/short 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

Data list reference table (Refer to ).

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. Voltage measurement at electronic-controlled throttle valve connector (TPS5 line).

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

(2)Ignition switch: ON

(3)Check the voltage between the electronic-controlled throttle valve connector (TPS5 line) and body earth.
OK: 4.9 - 5.1 V

Q. Is the check result normal?

	Go to Step 5.

	Go to Step 3.

STEP 3. Check of short to earth and open circuit in TPS5 line between electronic-controlled throttle valve 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

Data list reference table (Refer to ).

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 ).

	Replace the engine-ECU.

STEP 5. Check of harness damage in TPS5 line between electronic-controlled throttle valve connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 6.

	Repair the connector(s) or wiring harness.

STEP 6. Check of short to earth, open circuit and damage in TPSM line between electronic-controlled throttle valve connector and engine-ECU connector.

Q. Is the check result normal?

	Go to Step 7.

	Repair the connector(s) or wiring harness.

STEP 7. Replace the electronic-controlled throttle valve

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

Q. Is diagnosis code stored?

	Replace the engine-ECU.

	Check end.