Code No. P2138: Accelerator Pedal Position Sensor (Main and Sub) Range/Performance Problem


OPERATION



  • Refer to Code No. P2122: Accelerator Pedal Position Sensor (main) Circuit Low Input .
  • Refer to Code No. P2127: Accelerator Pedal Position Sensor (sub) Circuit Low Input .

FUNCTION



  • Engine-ECU checks the accelerator pedal position sensor output signal characteristics for abnormal conditions.

TROUBLE JUDGMENT


Check Condition
  • Ignition switch is in "ON" position.
Judgment Criterion
  • When an error is detected on the High side of the accelerator pedal position (main), the accelerator pedal position sensor (sub) is faulty on the High/Low side.
Check Conditions
  • Battery positive voltage is 8 - 16 V
  • 2 seconds later after the ignition switch has been in "ON" position or the engine has started up
  • Engine speed is 600 r/min or more.
  • Accelerator pedal position sensor (main) output voltage is 0.2 V or higher and 4.8 V or lower.
  • Accelerator pedal position sensor (sub) output voltage is 0.125 V or higher and 2.375 V or lower.
Judgment Criterion
  • When a change in the accelerator pedal position sensor (sub) output voltage is less than the specified value, the difference between the opening indicated by the accelerator pedal position sensor (main) and that by the accelerator pedal position sensor (sub) is 20 % or more of the specified value.

FAIL-SAFE AND BACKUP FUNCTION



  • The accelerator pedal opening is controlled to be 0 %.
  • The idle speed is 1,300 r/min (Both of the main and substitute APSs are failed or their characteristics are abnormal).

PROBABLE CAUSES



  • Failed accelerator pedal position sensor
  • Harness damage in accelerator pedal position sensor circuit or loose connector contact
  • Failed engine-ECU

DIAGNOSIS PROCEDURE

STEP 1. 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 2.

    Repair or replace the connector, or check and repair harness between accelerator pedal position sensor connector terminal and engine-ECU connector terminal APSE.

    • Check earthing line for damage.

STEP 2. Perform resistance measurement at accelerator pedal position sensor connector.

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

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

    Repair or replace the connector, or check and repair harness between accelerator pedal position sensor connector terminal and engine-ECU connector terminal APE.

    • Check earthing line for damage.

STEP 3. Perform voltage measurement at 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 engine-ECU APS5 line and body earth.
OK: 4.9 - 5.1 V

Q. Is the check result normal?
Go to Step 4.

    Repair or replace the connector, or check and repair harness between accelerator pedal position sensor connector terminal and engine-ECU connector terminal APS5.

    • Check power supply line for damage.

STEP 4. Perform voltage measurement at 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 engine-ECU AP5 line and body earth.
OK: 4.9 - 5.1 V

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

    Repair or replace the connector, or check and repair harness between accelerator pedal position sensor connector terminal and engine-ECU connector terminal AP5.

    • Check power supply line for damage.

STEP 5. Perform voltage measurement at engine-ECU connector.

  • Disconnect engine-ECU harness, and connect special tool power plant ECU check harness (MB992291) to measure at connector for inspection.
  • Ignition switch: ON
  • Voltage between terminal APSM and body earth.
OK: 0.7 - 1.3 V

Q. Is the check result normal?
Go to Step 7.
Go to Step 6.

STEP 6. Check harness between accelerator pedal position sensor connector terminal and engine-ECU connector terminal APSM.

  • Check output line for damage.

Q. Is the check result normal?
Replace the accelerator pedal assembly.
Repair or replace the connector, or repair the damaged harness wire.

STEP 7. Perform voltage measurement at engine-ECU connector.

  • Disconnect engine-ECU harness, and connect special tool power plant ECU check harness (MB992291) to measure at connector for inspection.
  • Ignition switch: ON
  • Voltage between terminal APSS and body earth.
OK: 0.2 - 0.8 V

Q. Is the check result normal?
Go to Step 9.
Go to Step 8.

STEP 8. Check harness between accelerator pedal position sensor connector terminal and engine-ECU connector terminal APSS.

  • Check output line for damage.

Q. Is the check result normal?
Replace the accelerator pedal assembly.
Repair or replace the connector, or repair the damaged harness wire.

STEP 9. M.U.T.-III diagnosis code

  • Reconfirmation of diagnosis code.

Q. Is the check result normal?
Replace the engine-ECU.
Intermittent malfunction (Refer to GROUP 00 - How to Use Troubleshooting/Inspection Service Points - How to Cope with Intermittent Malfunctions ).