Mitsubishi L200. Manual — part 295
TROUBLESHOOTING
AUTOMATIC TRANSMISSION
23A-87
STEP 4. Engine system check
Q: Is the check result normal?
YES :
Replace the A/T-ECU.
NO :
Repair the engine system.
Inspection Procedure 7: Shift Shock when Shifting from N to D and Long Delay
COMMENTS ON TROUBLE SYMPTOM
If abnormal shock or delay of two seconds or more
occurs when the selector lever is shifted from N to D
range while the engine is idling, the cause is proba-
bly abnormal underdrive clutch pressure or a mal-
function of the underdrive clutch, valve body or
throttle position sensor.
PROBABLE CAUSES
• Malfunction of underdrive solenoid valve
• Malfunction of input shaft speed sensor
• Abnormal underdrive clutch pressure
• Malfunction of throttle position sensor
• Malfunction of the underdrive clutch
• Malfunction of valve body
• Malfunction of the A/T-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III actuator test
Item 02: Underdrive solenoid valve
OK: Operating sound can be heard.
Q: Is the check result normal?
YES :
Go to Step 2.
NO :
Replace the underdrive solenoid valve.
STEP 2. M.U.T.-III data list
Item 05: Input shaft speed sensor (Refer to data list
reference table
Q: Is the check result normal?
YES :
Go to Step 3.
NO :
Refer to diagnosis code P1766: Input shaft
speed sensor system
STEP 3. M.U.T.-III data list
Item 13: Underdrive solenoid valve duty ratio (Refer
to data list reference table
).
Q: Is the check result normal?
YES :
Go to Step 4.
NO :
Replace the A/T-ECU.
STEP 4. Check when shift shock occurs.
Q: Does the shift shock occur when the vehicle starts
moving?
YES :
Go to Step 6.
NO :
Go to Step 5.
STEP 5. Hydraulic pressure test
Measure the hydraulic pressure for underdrive clutch
when the selector lever is shifted from N to D range.
OK: Refer to
.
Q: Is the check result normal?
YES :
Go to Step 9.
NO :
Go to Step 8.
STEP 6. Check when shift shock occurs.
Q: Does the shift shock always occur?
YES :
Go to Step 8.
NO :
Go to Step 7.
STEP 7. M.U.T.-III data list
Item 35: Accelerator pedal position sensor (Refer to
data list reference table
).
Q: Is the check result normal?
YES :
Go to Step 8.
NO :
Check the throttle position sensor system
(Refer to GROUP 13A, Troubleshooting ).
STEP 8. Valve body disassembly clean and
assembly
(1) Check the bolts for looseness and the O-ring,
solenoid valve and valve body for damage.
Replace the valve body assembly if the damages
are thought to be irreparable.
(2) Test drive the vehicle.
(3) Verify that the condition described by the
customer exists.
Q: Does a malfunction take place again?
YES :
Go to Step 9.
NO :
The inspection is complete.
STEP 9. Underdrive clutch check
Check the facing for seizure and the piston seal ring
for damage and interference with the retainer.
Q: Is the check result normal?
YES :
The inspection is complete.
NO :
Repair or replace the underdrive clutch.
TROUBLESHOOTING
AUTOMATIC TRANSMISSION
23A-88
Inspection Procedure 8: Shift Shock when Shifting from N to R and Long Delay
COMMENTS ON TROUBLE SYMPTOM
If abnormal shock or delay of two seconds or more
occurs when the selector lever is shifted from N to R
range while the engine is idling, the cause is proba-
bly abnormal pressure in reverse clutch and low-
reverse clutch or a malfunction of the reverse clutch,
low-reverse brake, valve body or throttle position
sensor.
PROBABLE CAUSES
• Malfunction of low-reverse solenoid valve
• Malfunction of input shaft speed sensor
• Malfunction of the inhibitor switch
• Abnormal reverse clutch pressure
• Abnormal low-reverse brake pressure
• Malfunction of accelerator pedal position sensor
• Malfunction of the reverse clutch
• Malfunction of low-reverse brake
• Malfunction of valve body
• Malfunction of the A/T-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III actuator test
Item 01: Low-reverse solenoid valve
OK: Operating sound can be heard.
Q: Is the check result normal?
YES :
Go to Step 2.
NO :
Replace the low-reverse solenoid valve.
STEP 2. M.U.T.-III data list
Item 05: Input shaft speed sensor (Refer to data list
reference table
Q: Is the check result normal?
YES :
Go to Step 3.
NO :
Refer to diagnosis code P1766: Input shaft
speed sensor system
STEP 3. M.U.T.-III diagnosis code
Either of diagnosis codes P1770 (P0705) or P1771
(P0705) is set, inhibitor switch is defective.
Q: Are diagnosis codes P1770 (P0705) or P1771
(P0705) output?
YES <diagnosis code P1770 (P0705) is set> :
Refer
to diagnosis code P1770 (P0705): Inhibitor
switch system
<4A/T>,
<5A/T>.
YES <diagnosis code P1771 (P0705) is set> :
Refer
to diagnosis code P1771 (P0705): Inhibitor
switch system
<4A/T>,
<5A/T>.
NO :
Go to Step 4.
STEP 4. M.U.T.-III data list
Item 12: Low-reverse solenoid valve duty ratio (Refer
to data list reference table
).
Q: Is the check result normal?
YES :
Go to Step 5.
NO :
Replace the A/T-ECU.
STEP 5. Check when shift shock occurs.
Q: Does the shift shock occur when the vehicle starts
moving?
YES :
Go to Step 7.
NO :
Go to Step 6.
STEP 6. Hydraulic pressure test
Measure the hydraulic pressure for reverse clutch
and low-reverse clutch when the selector lever is
shifted from N to R range.
OK: Refer to
.
Q: Is the check result normal?
YES :
Go to Step 10.
NO :
Go to Step 9.
STEP 7. Check when shift shock occurs.
Q: Does the shift shock always occur?
YES :
Go to Step 9.
NO :
Go to Step 8.
STEP 8. M.U.T.-III data list
Item 35: Accelerator pedal position sensor (Refer to
data list reference table
).
Q: Is the check result normal?
YES :
Go to Step 9.
NO :
Check the throttle position sensor system
(Refer to GROUP 13A, Troubleshooting ).
STEP 9. Valve body disassembly clean and
assembly
(1) Check the bolts for looseness and the O-ring,
TROUBLESHOOTING
AUTOMATIC TRANSMISSION
23A-89
solenoid valve and valve body for damage.
Replace the valve body assembly if the damages
are thought to be irreparable.
(2) Test drive the vehicle.
(3) Verify that the condition described by the
customer exists.
Q: Does a malfunction take place again?
YES :
Go to Step 10.
NO :
The inspection is complete.
STEP 10. Reverse clutch and low-reverse brake
check
Check the facing for seizure and the piston seal ring
for damage and interference with the retainer.
Q: Is the check result normal?
YES :
The inspection is complete.
NO :
Repair or replace the reverse clutch and
low-reverse brake.
Inspection Procedure 9: Shift Shock when Shifting from N to D, N to R and Long Delay
COMMENTS ON TROUBLE SYMPTOM
If abnormal shock or delay of two seconds or more
occurs when the selector lever is shifted from N to D
range and from N to R range while the engine is
idling, the cause is probably abnormal line pressure
or a malfunction of the oil pump, valve body.
PROBABLE CAUSES
• Abnormal line pressure
• Malfunction of throttle position sensor
• Malfunction of oil pump
• Malfunction of valve body
• Malfunction of the A/T-ECU
DIAGNOSIS PROCEDURE
STEP 1. Hydraulic pressure test
Measure the hydraulic pressure of each element
when the selector lever is 2, L range, sport mode
(1st, 2nd gear) or reverse.
.
Q: Is the check result normal?
YES :
Go to Step 3.
NO :
Go to Step 2.
STEP 2. Line pressure adjustment
(1) Adjust the line pressure (Refer to
(2) Test drive the vehicle.
(3) Verify that the condition described by the
customer exists.
Q: Does a malfunction take place again?
YES :
Go to Step 3.
NO :
The inspection is complete.
STEP 3. Check when shift shock occurs.
Q: Does the shift shock occur when the vehicle starts
moving?
YES :
Go to Step 4.
NO :
Check the oil pump for incorrect installation,
damage and etc., and replace the oil pump
assembly if necessary (The oil pump cannot
be disassembled.)
STEP 4. Check when shift shock occurs.
Q: Does the shift shock always occur?
YES :
Go to Step 7.
NO :
Go to Step 5.
STEP 5. M.U.T.-III data list
Item 35: Accelerator pedal position sensor (Refer to
data list reference table
).
Q: Is the check result normal?
YES :
Go to Step 6.
NO :
Check the throttle position sensor system
(Refer to GROUP 13A, Troubleshooting ).
STEP 6. A/T-ECU replacement
(1) Replace the A/T-ECU.
(2) Test drive the vehicle.
(3) Verify that the condition described by the
customer exists.
Q: Does a malfunction take place again?
YES :
Go to Step 7.
NO :
The inspection is complete.
STEP 7. Valve body disassembly clean and
assembly
Check the bolts for looseness and the O-ring, sole-
noid valve and valve body for damage.
Q: Is the check result normal?
YES :
The inspection is complete.
NO :
Replace the valve body assembly if the
damages are thought to be irreparable.
TROUBLESHOOTING
AUTOMATIC TRANSMISSION
23A-90
Inspection Procedure 10: Shift Shock and Slipping
COMMENTS ON TROUBLE SYMPTOM
If shift shock when driving are due to upshifting or
downshifting and the transmission speed become
higher than the engine speed, the cause is probably
abnormal line pressure or a malfunction of a solenoid
valve, oil pump, valve body or of a brake or clutch.
PROBABLE CAUSES
• Malfunction of each solenoid valve
• Abnormal line pressure
• Malfunction of valve body
• Malfunction of oil pump
• Malfunction of each brake or each clutch
• Malfunction of the A/T-ECU
DIAGNOSIS PROCEDURE
STEP 1. M.U.T.-III actuator test
• Item 01: Low-reverse solenoid valve
• Item 02: Underdrive solenoid valve
• Item 03: Second solenoid valve
• Item 04: Overdrive solenoid valve
• Item 05: Reduction solenoid valve <5A/T>
OK: Operating sound can be heard.
Q: Is the check result normal?
YES :
Go to Step 2.
NO :
Replace the defective solenoid valve.
STEP 2. M.U.T.-III data list
• Item 11: Shift position (Refer to data list reference
).
• Item 12, 13, 14, 15, 16 <5A/T>: Each solenoid
valve duty ratio (Refer to data list reference table
).
Q: Is the check result normal?
YES :
Go to Step 3.
NO :
Replace the A/T-ECU.
STEP 3. Hydraulic pressure test
Check all hydraulic pressures within the standard
value.
OK: Refer to
.
Q: Is the check result normal?
YES :
Go to Step 6.
NO :
Go to Step 4.
STEP 4. Line pressure adjustment
(1) Adjust the line pressure (Refer to
(2) Test drive the vehicle.
(3) Verify that the condition described by the
customer exists.
Q: Does a malfunction take place again?
YES :
Go to Step 5.
NO :
The inspection is complete.
STEP 5. Valve body disassembly clean and
assembly
(1) Check the bolts for looseness and the O-ring,
solenoid valve and valve body for damage.
Replace the valve body assembly if the damages
are thought to be irreparable.
(2) Test drive the vehicle.
(3) Verify that the condition described by the
customer exists.
Q: Does a malfunction take place again?
YES :
Check the oil pump for incorrect installation,
damage and etc., and replace the oil pump
assembly if necessary (The oil pump cannot
be disassembled).
NO :
The inspection is complete.
STEP 6. Each clutch and brake check
Check the facing for seizure and the piston seal ring
for damage and interference with the retainer.
Q: Is the check result normal?
YES :
The inspection is complete.
NO :
Repair or replace each clutch and brake.
Inspection Procedure 11: Does not Shift Properly (all Points)
COMMENTS ON TROUBLE SYMPTOM
If all shift points are early or late while driving, the
cause is probably a malfunction of the output shaft
speed sensor, throttle position sensor, or A/T-ECU.
PROBABLE CAUSES
• Malfunction of output shaft speed sensor
• Malfunction of throttle position sensor
• Malfunction of the A/T-ECU
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