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Home >> Mitsubishi >> 2002 >> Montero XLS >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Diagnosis - R4A51, V4A51 & V5A51 >> Diagnostic Tests >> DTC 41 (P0731): 1ST Gear Ratio Incorrect >> Diagnostic Procedure

Diagnostic Procedure

CAUTION: To prevent damage to scan tool, always turn the ignition off before connecting or disconnecting scan tool.
  1. Using scan tool, check for DTCs. Is DTCs 22 or 23 present? If so, see DTC 22 (P0715): INPUT SHAFT SPEED SENSOR CIRCUIT - OPEN/SHORTED  and/or DTC 23 (P0720): OUTPUT SHAFT SPEED SENSOR CIRCUIT - OPEN/SHORTED  . If not, go to next step.
  2. Turn ignition on. Using scan tool, command the following solenoids on and off:
    • Low-Reverse Solenoid Valve
    • Underdrive Solenoid Valve
    • Second Solenoid Valve
    • Overdrive Solenoid Valve
    • Reduction Solenoid Valve (5-Speed)

    A clicking sound should be heard from each solenoid valve when operated. Turn ignition off. Are the solenoid valves operating properly? If so, go to next step. If not, replace the faulty solenoid valve. See appropriate SERVICING article.

  3. Using the oscilloscope, check the waveform of the input shaft speed sensor at PCM harness connectors by backprobing. Do not disconnect harness connectors. Connect an oscilloscope probe to PCM harness connector terminals No. 57 and 103. Operate vehicle in 3rd gear (4-speed) or 4th gear (5-speed) at 31 MPH. Check the waveform. The waveform should show a pattern similar to the illustration. See Figure . The waveform voltage value should be 0.8-4.8 volts. The output waveform should not contain electrical noise. Turn ignition off. Is the waveform normal? If so, go to step  8 . If not, go to next step.
  4. Check all speed sensor circuit harness connectors between PCM and input shaft speed sensor for damage. Are the harness connectors in good condition? If so, go to next step. If not, repair or replace the defective harness connector(s).
  5. Check wire harness for damage between input shaft speed sensor harness connector terminal No. 2 and PCM harness connector terminal No. 103. Is the wire harness in good condition? If so, go to next step. If not, repair wire harness as necessary.
  6. Replace the input shaft speed sensor. See appropriate SERVICING article. Test drive the vehicle. Using scan tool, check for DTCs. Is the DTC 41 present? If so, go to next step. If not, inspection is complete.
  7. Replace the reverse clutch retainer. See appropriate OVERHAUL article. Test drive the vehicle. Using scan tool, check for DTCs. Is the DTC 41 present? If so, DTC may have set due to Radio Frequency Interference (RFI), possibly caused by cellular phone activity, after market components installed on the vehicle, etc. If not, inspection is complete.
  8. Using the oscilloscope, check the waveform of the output shaft speed sensor at PCM harness connectors by backprobing. Do not disconnect harness connectors. Connect an oscilloscope probe to PCM harness connector terminal No. 57 and 104. Operate vehicle in 3rd gear (4-speed) or 4th gear (5-speed) at 31 MPH. Check the waveform. The waveform should show a pattern similar to the illustration. See Figure . The waveform voltage value should be 0.8-4.8 volts. The output waveform should not contain electrical noise. Turn ignition off. Is the waveform normal? If so, go to step  13 . If not, go to next step.
  9. Check all speed sensor circuit harness connectors between PCM and output shaft speed sensor for damage. Are the harness connectors in good condition? If so, go to next step. If not, repair or replace the defective harness connector(s).
  10. Check wire harness for damage between output shaft speed sensor harness connector terminal No. 2 and PCM harness connector terminal No. 104. Is the wire harness in good condition? If so, go to next step. If not, repair wire harness as necessary.
  11. Replace the output shaft speed sensor. See appropriate SERVICING article. Test drive the vehicle. Using scan tool, check for DTCs. Is the DTC 41 present? If so, go to next step. If not, inspection is complete.
  12. Replace the output shaft (4-speed) or direct planetary carrier. See appropriate OVERHAUL article. Test drive the vehicle. Using scan tool, check for DTCs. Is the DTC 41 present? If so, the DTC may have set due to Radio Frequency Interference (RFI), possibly caused by cellular phone activity, after market components installed on the vehicle, etc. If not, inspection is complete.
  13. Replace the valve body. See appropriate SERVICING article. Using scan tool, check for DTCs. Is the DTC 41 present? If so, go to next step. If not, inspection is complete.
  14. Possible faulty PCM exists. Replace the PCM if necessary. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Test drive the vehicle. Using scan tool, check for DTCs. Is the DTC 41 present? If so, go to next step. If not, inspection is complete.
  15. Overhaul the transmission. See appropriate OVERHAUL article. Replace the following parts:
    • Underdrive Clutch
    • Low-Reverse Brake
    • Reduction Brake
    • One-Way Clutch

    Using scan tool, check for DTCs. Is the DTC 41 present? If so, the DTC may have set due to Radio Frequency Interference (RFI), possibly caused by cellular phone activity, after market components installed on the vehicle, etc. If not, inspection is complete.

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