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 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 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 circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list

  • Data list reference table (Refer to ).

  1. 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. Check harness between electronic-controlled throttle valve connector terminal and engine-ECU connector terminal TPS5.

  • Check power supply line for damage.

Q. Is the check result normal?
Go to Step 3.
Repair or replace the connector, or repair the damaged harness wire.

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

  • Check output line for short circuit.

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

  • Data list reference table (Refer to ).

  1. 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 5.

STEP 5. 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.