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Home >> Mitsubishi >> 2003 >> Montero XLS >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P2123: Accelerator Pedal Position Sensor (Main) Circuit High Input >> Diagnostic Procedure
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Diagnostic Procedure

CAUTION: To prevent damage to scan tool (MB991502), always turn the ignition off before connecting or disconnecting it.
  1. Using scan tool (MB991502), check data list item 78: ACCELERATOR PEDAL POSITION SENSOR (MAIN). Connect scan tool (MB991502) to the data link connector. Turn the ignition switch to the "ON" position. Set scan tool (MB991502) to the data reading mode for item 78: ACCELERATOR PEDAL POSITION SENSOR (MAIN). Output voltage is between 0.905 and 1.165 volts when foot is released from accelerator pedal. Output voltage is 4.035 volts or higher when accelerator pedal is fully depressed. Turn the ignition switch to the "LOCK" (OFF) position. If the sensor is operating properly, it can be assumed that this malfunction is intermittent. Refer to INTERMITTENT DIAGNOSTIC TROUBLE CODES , otherwise, go to the next step.
  2. Check connector D-138 at accelerator pedal position sensor for damage. If the connector is in good condition, go to the next step, otherwise, repair or replace it. Then go to step  8.
  3. Check the accelerator pedal position sensor. Disconnect the accelerator pedal position sensor connector D-138. Measure resistance between terminal No. 1 and No. 2 and between terminal No. 7 and No. 8. Standard value: 3.5 - 6.5 kiloohms Measure resistance between terminal No. 2 and No. 3 and between terminal No. 6 and No. 8. Move the accelerator pedal from the idle position to the full-open position. Resistance value changes in accordance with the accelerator pedal depression smoothly. If the resistance is normal, go to the next step, otherwise, replace the accelerator pedal position sensor. Then go to step  8.
  4. Check the continuity at accelerator pedal position sensor harness side connector D-138. Disconnect the connector D-138 and measure at the harness side. Measure the continuity between terminal No. 1 and ground. Should be less than 2 ohms. If the continuity is normal, go to step  7, otherwise, go to the next step.
  5. Check connector D-135 at PCM for damage. If the connector is in good condition, go to the next step, otherwise, repair or replace it. Then go to step  8.
  6. Check for open circuit and harness damage between accelerator pedal position sensor connector D- 138 (terminal No. 1) and PCM connector D-135 (terminal No. 91). If the harness wire is in good condition, go to the next step, otherwise, repair it. Then go to step  8.
  7. Using scan tool (MB991502), check data list item 78: ACCELERATOR PEDAL POSITION SENSOR (MAIN). Connect scan tool (MB991502) to the data link connector. Turn the ignition switch to the "ON" position. Set scan tool (MB991502) to the data reading mode for item 78: ACCELERATOR PEDAL POSITION SENSOR (MAIN). Output voltage is between 0.905 and 1.165 volts when foot is released from accelerator pedal. Output voltage is 4.035 volts or higher when accelerator pedal is fully depressed. Turn the ignition switch to the "LOCK" (OFF) position. If the sensor is operating properly, it can be assumed that this malfunction is intermittent. Refer to INTERMITTENT DIAGNOSTIC TROUBLE CODES , otherwise, replace the PCM. Then go to the next step.
  8. Using scan tool (MB991502), read the diagnostic trouble code (DTC). Connect scan tool (MB991502) to the data link connector. Turn the ignition switch to the "ON" position. After the DTC has been deleted, read the DTC again. Turn the ignition switch to the "LOCK" (OFF) position. If DTC P2123 sets, retry the troubleshooting, otherwise, the inspection is complete.
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