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. 2) from the engine-ECU <M/T> or engine-A/T-ECU <A/T> (terminal No. 106).
The power voltage is earthed to the engine-ECU <M/T> or engine-A/T-ECU <A/T> (terminal No. 105) from the electronic-controlled throttle valve (terminal No. 4).
The sensor signal is inputted to the engine-ECU <M/T> or engine-A/T-ECU <A/T> (terminal No. 115) from the electronic-controlled throttle valve output terminal (terminal No. 1).

FUNCTION

The throttle position sensor converts the throttle valve position into voltage and inputs it into the engine-ECU <M/T> or engine-A/T-ECU <A/T>.
The engine-ECU <M/T> or engine-A/T-ECU <A/T> controls the throttle valve position.

TROUBLE JUDGMENT

Check Condition

Ignition switch is in "ON" position.

Judgment Criterion

Throttle position sensor (main) output voltage is 0.35 V or less.

PROBABLE CAUSES

Failed throttle position sensor (main)
Open/short circuit in throttle position sensor circuit or loose connector contact
Failed engine-ECU <M/T> or engine-A/T-ECU <A/T>

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-31 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 B-31 electronic-controlled throttle valve connector.

Disconnect connector, and measure at harness side.
Ignition switch: ON
Voltage between terminal No. 2 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: D-246 engine-ECU <M/T> connector or D-217 engine-A/T-ECU <A/T> connector

Q. Is the check result normal?

	Go to Step 5 .

	Repair or replace the connector.

STEP 5. Check harness between B-31 (terminal No. 2) electronic-controlled throttle valve connector and D-246 (terminal No. 106) engine-ECU <M/T> connector or D-217 (terminal No. 106) engine-A/T-ECU <A/T> 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 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 <M/T> or engine-A/T-ECU <A/T>.

STEP 7. Connector check: D-246 engine-ECU <M/T> connector or D-217 engine-A/T-ECU <A/T> connector

Q. Is the check result normal?

	Go to Step 8 .

	Repair or replace the connector.

STEP 8. Check harness between B-31 (terminal No. 2) electronic-controlled throttle valve connector and D-246 (terminal No. 106) engine-ECU <M/T> connector or D-217 (terminal No. 106) engine-A/T-ECU <A/T> connector.

Check power supply line for damage.

Q. Is the check result normal?

	Go to Step 9 .

	Repair the damaged harness wire.

STEP 9. Check harness between B-31 (terminal No. 1) electronic-controlled throttle valve connector and D-246 (terminal No. 115) engine-ECU <M/T> connector or D-217 (terminal No. 115) engine-A/T-ECU <A/T> connector.

Check output line for open/short circuit and damage.

Q. Is the check result normal?

	Go to Step 10 .

	Repair the damaged harness wire.

STEP 10. Replace the electronic-controlled throttle valve

After replacing the electronic-controlled throttle valve, re-check the trouble symptoms.

Q. Is the check result normal?

	Check end.

	Replace the engine-ECU <M/T> or engine-A/T-ECU <A/T>.