Code No. P2122: Accelerator Pedal Position Sensor (main) Circuit Low Input








OPERATION



  • A power voltage of 5 V is applied to the accelerator pedal position sensor (terminal No. 1) from the engine-ECU (terminal No. 149).
  • The power voltage is earthed to the engine-ECU (terminal No. 136) from the accelerator pedal position sensor (terminal No. 2).
  • The sensor signal is inputted to the engine-ECU (terminal No. 150) from the accelerator pedal position sensor output terminal (terminal No. 3).

FUNCTION



  • The accelerator pedal position sensor (main) outputs voltage which corresponds to the accelerator pedal depression.
  • The engine-ECU checks whether the voltage is within a specified range.

TROUBLE JUDGMENT


Check Conditions
  • Ignition switch is in "ON" position
  • Accelerator pedal position sensor (sub) is normal
Judgment Criterion
  • Accelerator pedal position sensor (main) output voltage is lower than 0.2 V.

PROBABLE CAUSES



  • Failed accelerator pedal position sensor
  • Open/short circuit in accelerator pedal position sensor circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

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

  • Refer to Data List Reference Table .

  1. Item 9: Accelerator pedal 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: D-202 accelerator pedal position sensor connector

Q. Is the check result normal?
Go to Step 3 .
Repair or replace the connector.

STEP 3. Perform voltage measurement at D-202 accelerator pedal position sensor connector.

  • Disconnect connector, and measure at harness side.
  • Ignition switch: ON
  • Voltage between terminal No. 1 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-215 engine-ECU connector

Q. Is the check result normal?
Go to Step 5 .
Repair or replace the connector.

STEP 5. Check harness between D-202 (terminal No. 1) accelerator pedal position sensor connector and D-215 (terminal No. 149) engine-ECU 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 .

  1. Item 9: Accelerator pedal 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. When the engine-ECU is replaced, write the chassis number (Refer to GROUP 00 - Precautions Before Service - How to Perform Chassis Number Writing ). After replacing the engine-ECU, register the injector identification code and learn fuel injection (Refer to GROUP 00 - Precautions Before Service - What The Common Rail Engine Learns ). After registering the injector identification code, the vehicle equipped with the closed type DPF carries out the forcible DPF regeneration. (Refer to GROUP 17 - Diesel Particulate Filter (DPF) System - Forcible DPF Regeneration ).

STEP 7. Perform resistance measurement at D-202 accelerator pedal position sensor connector.

  • Disconnect connector, and measure at harness side.
  • Resistance between terminal No. 2 and earth.
OK: Continuity (2 Ω or less)

Q. Is the check result normal?
Go to Step 10 .
Go to Step 8 .

STEP 8. Connector check: D-215 engine-ECU connector

Q. Is the check result normal?

    Go to Step 9 .
Repair or replace the connector.

STEP 9. Check harness between D-202 (terminal No. 2) accelerator pedal position sensor connector and D-215 (terminal No. 136) engine-ECU connector.

  • Check earthing line for damage.

Q. Is the check result normal?
Go to Step 6 .
Repair the damaged harness wire.

STEP 10. Connector check: D-215 engine-ECU connector

Q. Is the check result normal?
Go to Step 11 .
Repair or replace the connector.

STEP 11. Perform voltage measurement at D-202 accelerator pedal position sensor connector.

  • Use special tool test harness (MB991658) to connect connector, and measure at pick-up harness.
  • Ignition switch: ON
  • Voltage between terminal No. 3 and earth.
OK: 0.7 - 1.3 V

Q. Is the check result normal?
Go to Step 15 .
Go to Step 12 .

STEP 12. Connector check: D-215 engine-ECU connector.

Q. Is the check result normal?
Go to Step 13 .
Repair or replace the connector.

STEP 13. Check harness between D-202 (terminal No. 3) accelerator pedal position sensor and D-215 (terminal No. 150) engine-ECU connector.

  • Check output line for short circuit.

Q. Is the check result normal?
Go to Step 14 .
Repair the damaged harness wire.

STEP 14. Check harness between D-202 (terminal No. 1) accelerator pedal position sensor connector and D-215 (terminal No. 149) engine-ECU connector.

  • Check power supply line for damage.

Q. Is the check result normal?
Replace the accelerator pedal assembly.
Repair the damaged harness wire.

STEP 15. Check harness between D-202 (terminal No. 3) accelerator pedal position sensor connector and D-215 (terminal No. 150) engine-ECU connector.

  • Check output line for open circuit and damage.

Q. Is the check result normal?
Go to Step 6 .
Repair the damaged harness wire.