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. 75).
  • The power voltage is earthed to the engine-ECU (terminal No. 76) from the accelerator pedal position sensor (terminal No. 2).
  • The sensor signal is inputted to the engine-ECU (terminal No. 74) 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 Condition
  • Ignition switch is "ON" position.
Judgement Criterion
  • Accelerator pedal 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 accelerator pedal position sensor (sub) fails.

PROBABLE CAUSES



  • Failed accelerator pedal position sensor
  • Open/short circuit or harness damage in accelerator pedal 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 11: 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: C-23 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 C-23 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: B-27 engine-ECU connector

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

STEP 5. Check harness between C-23 (terminal No. 1) accelerator pedal position sensor connector and B-27 (terminal No. 75) 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

  • Data list reference table (Refer to ).

  1. Item 11: 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.

STEP 7. Connector check: B-27 engine-ECU connector

Q. Is the check result normal?
Go to Step 8 .
Repair or replace the connector.

STEP 8. Check harness between C-23 (terminal No. 1) accelerator pedal position sensor connector and B-27 (terminal No. 75) engine-ECU 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 C-23 (terminal No. 3) accelerator pedal position sensor connector and B-27 (terminal No. 74) engine-ECU 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 accelerator pedal assembly

  • After replacing the accelerator pedal assembly, reconfirm whether the diagnosis code is set.

Q. Is the diagnosis code set?
Replace the engine-ECU.
Check end.