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Home >> Mitsubishi >> 2002 >> Montero XLS >> Repair and Diagnosis >> Transmission >> Automatic Trans >> Diagnosis - R4A51, V4A51 & V5A51 >> Symptom Tests >> Test F: Shock Or Lag Time When Shifting From Neutral To Drive >> Diagnostic Procedure

Diagnostic Procedure

  1. Using scan tool, command underdrive solenoid valve on and off. A clicking sound should be heard from solenoid valve when operated. Turn ignition off. Is the solenoid valve operating properly? If so, go to next step. If not, repair or replace the underdrive solenoid valve. See appropriate SERVICING article. Confirm symptom is eliminated.
  2. Check when shift shock occurs. When does the shift shock occur? If shock occurs when engaging from Neutral to Drive, go to next step. If shock occurs when the vehicle starts moving, go to step  6 .
  3. Check the hydraulic pressure of underdrive clutch. See HYDRAULIC PRESSURE TESTS  under PERFORMANCE TESTS. Measure the hydraulic pressure for underdrive clutch when the gearshift lever is moved from "N" to "D" position. Is the hydraulic pressure within the standard value? If so, go to next step. If not, go to step  8 .
  4. Check the underdrive clutch system. Remove the valve body cover and valve body. See appropriate SERVICING article. Apply 15 psi of compressed air into the underdrive clutch oil orifice of the transmission case. See Figure . Check if the underdrive clutch piston moves and air pressure is maintained in that condition. Is the air pressure maintained? If so, go to step  8 . If not, go to next step.
  5. Remove the transmission assembly. Check the underdrive clutch. Check the facing for seizure and the piston seal ring for damage and interference with the retainer. Repair or replace the faulty parts. Check the symptom. Is the symptom eliminated? If so, diagnosis is complete. If not, go to step  9 .
  6. Check shift shock. Does shift shock occur? If so, go to next step. If not, go to step  8 .
  7. Using scan tool, monitor TP sensor. With the throttle in idle position, voltage should be 535-735 millivolts. With the throttle in fully opened position, voltage should be 4500-5500 millivolts. Turn ignition off. Is the TP sensor operating properly? If so, go to next step. If not, check the TP sensor. Repair as necessary. Then check the symptom.
  8. Disassemble and clean the valve body. See appropriate OVERHAUL article. Check the "O" ring installation, bolts for looseness and the valve body for damage. Repair or replace faulty parts. Is the repair possible and the symptom eliminated? If so, diagnosis is complete. If not, replace the valve body assembly. Check the symptom. Is the symptom eliminated? If so, diagnosis is complete. If not, go to next step.
  9. Possible faulty PCM exists. Replace the PCM if necessary. See POWERTRAIN CONTROL MODULE  under REMOVAL & INSTALLATION. Is the symptom eliminated? If so, diagnosis is complete. If not, go to step  1 .
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