Code No. P2123: Accelerator Pedal Position Sensor (main) Circuit High Input


OPERATION



  • A power voltage of 5 V is applied to the accelerator pedal position sensor connector terminal from the engine-ECU connector terminal APS5.
  • The power voltage is earthed to the engine-ECU connector terminal APSE from the accelerator pedal position sensor connector terminal.
  • The sensor signal is inputted to the engine-ECU connector terminal APSM from the accelerator pedal position sensor output terminal.

FUNCTION



  • The accelerator pedal position sensor converts the opening degree of the accelerator pedal into the voltage signal to input it to the engine ECU.
  • The engine ECU uses this signal to determine the amount of basic fuel injection.

TROUBLE JUDGMENT


Check Conditions
  • Ignition switch is in "ON" position
  • Accelerator pedal position sensor (sub) is normal
  • Accelerator pedal position sensor (sub) output voltage is 0.125 V or higher and 1.4 V or lower.
  • Diagnosis code No. P2124 is memorized.
Judgment Criterion
  • Accelerator pedal position sensor (main) output voltage is 4.8 V or more.

FAIL-SAFE AND BACKUP FUNCTION



  • The amount of depression of the accelerator pedal is detected, using the accelerator pedal position sensor (sub) signal, which is calculated by taking half of the normal value.

PROBABLE CAUSES



  • Failed accelerator pedal position sensor
  • Open 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

  • 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. Perform resistance measurement at accelerator pedal position sensor connector.

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

Q. Is the check result normal?
Go to Step 5.
Go to Step 3.

STEP 3. Check harness between accelerator pedal position sensor connector terminal and engine-ECU connector terminal APSE.

  • Check earthing 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.

STEP 4. 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.

STEP 5. Replace the accelerator pedal assembly

  • After replacing the accelerator pedal assembly, re-check the trouble symptoms.

Q. Is the check result normal?
The check is end.
Replace the engine-ECU.