Code No. P0122: Throttle Position Sensor Circuit Low Input




OPERATION




FUNCTION




TROUBLE JUDGMENT


Check Conditions
Judgment Criterion

FAIL-SAFE AND BACKUP FUNCTION




PROBABLE CAUSES




DIAGNOSTIC PROCEDURE


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



  • Refer to Data List Reference Table .

  1. 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. Perform voltage measurement at throttle body assembly connector.



  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal engine-ECU 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 harness between throttle body assembly connector terminal and engine-ECU connector terminal TPS5.



  • Check power supply line for open/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



  • Refer to Data List Reference Table .

  1. 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. Perform resistance measurement at throttle body assembly connector.



  • Disconnect connector, and measure at harness side.
  • Resistance between terminal engine-ECU TPSE line and body earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?

Go to Step 7.
Go to Step 6.

STEP 6. Check harness between throttle body assembly connector terminal and engine-ECU connector terminal TPSE.



  • Check earthing line for damage.

Q. Is the check result normal?

Go to Step 4.
Repair or replace the connector, or repair the damaged harness wire.

STEP 7. Perform voltage measurement at throttle body assembly connector.



  • Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.
  • Ignition switch: ON
  • Voltage between terminal engine-ECU TPSM line and body earth.
OK: 3.7 V or higher

Q. Is the check result normal?

Go to Step 10.
Go to Step 8.

STEP 8. Check harness between throttle body assembly connector terminal and engine-ECU connector terminal TPSM.



  • Check output line for short circuit.

Q. Is the check result normal?

Go to Step 9.
Repair or replace the connector, or repair the damaged harness wire.

STEP 9. Check harness between throttle body assembly connector terminal and engine-ECU connector terminal TPS5.



  • Check power supply line for damage.

Q. Is the check result normal?

Replace the throttle body assembly.
Repair or replace the connector, or repair the damaged harness wire.

STEP 10. Check harness between throttle body assembly connector terminal and engine-ECU connector terminal TPSM.



  • Check output line for open circuit and damage.

Q. Is the check result normal?

Go to Step 4.
Repair or replace the connector, or repair the damaged harness wire.