Mitsubishi Colt Ralliart. Manual - part 194

TROUBLESHOOTING <CVT>

CVT

23A-119

Inspection Procedure 6: Fault During Driving (Poor Acceleration)

COMMENTS ON TROUBLE SYMPTOM

If transmission does not downshift (kickdown) with 
the accelerator pedal fully depressed, the engine 
system or the valve body system may be defective.

PROBABLE CAUSES

• Malfunction of forward clutch

• Malfunction of reverse brake

• Malfunction of the engine-CVT-ECU

• Malfunction of the engine system

• Malfunction of valve body assembly

• Malfunction of the shift control solenoid valve

• Malfunction of line pressure control solenoid 

valve

DIAGNOSIS PROCEDURE

STEP 1. Engine system check
Refer to GROUP 13A 

− Troubleshooting, Inspection 

Chart for Trouble Symptoms 

P.13A-231

.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Check for the relevant trouble symptom.

STEP 2. M.U.T.-III actuator test
Item 01: Line pressure control solenoid valve

OK: Operating sound can be heard.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Replace the CVT assembly.

STEP 3. M.U.T.-III actuator test
Item 02: Shift control solenoid valve

OK: Operating sound can be heard.

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Refer to code No.32, 36: Shift control 
solenoid valve system 

P.23A-82

.

STEP 4. Hydraulic pressure test.
Measure the following fluid pressures (Refer to 

P.23A-140

).

a. Forward clutch pressure
b. Reverse brake pressure

c. Line pressure

OK: Refer to 

P.23A-140

.

Q: Is the check result normal?

YES : 

Go to Step 9.

NO <"NG" for all items> : 

Replace the CVT 

assembly.

NO <"NG" for both "a" and "b"> : 

Go to Step 5.

NO <"NG" for either "a" or "b"> : 

Go to Step 7.

STEP 5. Replace the engine-CVT-ECU and then 
recheck the symptom.
(1) Replace the engine-CVT-ECU.
(2) Test drive the vehicle.
(3) Check the trouble symptom again.

Q: Does a malfunction take place again?

YES : . 

Go to Step 6.

NO : . 

The inspection is complete.

STEP 6. Disassemble, clean and assemble the 
valve body assembly.
Check the mounting bolts for looseness, and the 
O-ring, solenoid valve and valve body for damage.

Q: Is the check result normal?

YES : 

The inspection is complete.

NO : 

Replace the valve body assembly.

STEP 7. Check the forward clutch system and 
reverse brake system.
(1) Remove the transmission assembly, the valve 

body cover and the valve body assembly.

(2) Blow air into the forward clutch and the reverse 

brake oil holes on the transmission case. Check 
that the piston moves and the air pressure is 
maintained.

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Go to Step 8.

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TROUBLESHOOTING <CVT>

CVT

23A-120

STEP 8. Check the forward clutch and reverse 
brake.
Check the facing for seizure and the piston seal ring 
for damage and interference with the retainer (Refer 
to GROUP 23B - Forward Clutch 

P.23B-31

 or 

Reverse Brake 

P.23B-34

).

Q: Is the check result normal?

YES : 

The inspection is complete.

NO : 

Repair or replace the forward clutch and the 
reverse brake.

STEP 9. Retest the system.
(1) Test drive the vehicle.
(2) Check the trouble symptom again.

Q: Does a malfunction take place again?

YES : 

Replace the CVT assembly.

NO : 

The inspection is complete.

Inspection Procedure 7: Fault During Driving (Vibration)

COMMENTS ON TROUBLE SYMPTOM

If vibration is produced during driving at 20 km/h or 
more, the torque converter (damper clutch) pressure, 
the engine system, the damper clutch control sole-
noid valve, the torque converter (damper clutch) or 
the valve body may be faulty.

PROBABLE CAUSES

• Malfunction of torque converter pressure

• Malfunction of engine system

• Malfunction of damper clutch control solenoid 

valve

• Malfunction of torque converter

• Malfunction of valve body assembly

• Malfunction of engine-CVT-ECU

• Malfunction of the line pressure control solenoid 

valve

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III actuator test
Item 01: Line pressure control solenoid valve

OK: Operating sound can be heard.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Replace the CVT assembly.

STEP 2. M.U.T.-III actuator test
Item 03: Damper clutch control solenoid valve

OK: Operating sound can be heard.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Refer to code No.33, 37: Damper clutch 
control solenoid valve system 

P.23A-86

.

STEP 3. Hydraulic pressure test.
Measure the torque converter hydraulic pressure 
(Refer to 

P.23A-140

).

OK: Refer to 

P.23A-140

.

Q: Is the check result normal?

YES : 

Replace the torque converter.

NO : 

Go to Step 4.

STEP 4. Disassemble, clean and assemble the 
valve body assembly.
Check the mounting bolts for looseness, and the 
O-ring, solenoid valve and valve body for damage.

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Replace the valve body assembly.

STEP 5. Retest the system.
(1) Test drive the vehicle.
(2) Check the trouble symptom again.

Q: Does a malfunction take place again?

YES : 

Replace the engine-CVT-ECU.

NO : 

The inspection is complete.

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TROUBLESHOOTING <CVT>

CVT

23A-121

Inspection Procedure 8: Fault During Driving (Excessive Engine Brake Operated)

COMMENTS ON TROUBLE SYMPTOM

If you feel a sense of "engine braking with low gear 
engaged" during driving downhill, the engine system 
or the valve body system may be defective.

PROBABLE CAUSES

• Aging of CVT fluid

• Malfunction of valve body assembly

• Malfunction of the shift control solenoid valve

• Malfunction of the engine-CVT-ECU

• Malfunction of the primary pressure sensor

• Malfunction of the engine system

DIAGNOSIS PROCEDURE

STEP 1. Engine system check
Refer to GROUP 13A 

− Troubleshooting, Inspection 

Chart for Trouble Symptoms 

P.13A-231

.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Check for the relevant trouble symptom.

STEP 2. M.U.T.-III actuator test
Item 02: Shift control solenoid valve

OK: Operating sound can be heard.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Refer to code No.32, 36: Shift control 
solenoid valve system 

P.23A-82

.

STEP 3. M.U.T.-III data list
Item 11: Primary pressure sensor (Refer to Data List 
Table 

P.23A-123

).

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Replace the primary pressure sensor (Refer 
to 

P.23A-155

).

STEP 4. Hydraulic pressure test.
Measure the primary hydraulic pressure (Refer to 

P.23A-140

).

OK: Refer to 

P.23A-140

.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Go to Step 5.

STEP 5. Replace the engine-CVT-ECU and then 
recheck the symptom.
(1) Replace the engine-CVT-ECU.
(2) Test drive the vehicle.
(3) Check the trouble symptom again.

Q: Does a malfunction take place again?

YES : 

Go to Step 6.

NO : 

The inspection is complete.

STEP 6. Disassemble, clean and assemble the 
valve body assembly.
Check the mounting bolts for looseness, and the 
O-ring, solenoid valve and valve body for damage.

Q: Is the check result normal?

YES : 

The inspection is complete.

NO : 

Replace the valve body assembly.

STEP 7. Replace the engine-CVT-ECU and then 
recheck the symptom.
(1) Replace the engine-CVT-ECU.
(2) Test drive the vehicle.
(3) Check the trouble symptom again.

Q: Does a malfunction take place again?

YES : 

Replace the CVT assembly.

NO : 

The inspection is complete.

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TROUBLESHOOTING <CVT>

CVT

23A-122

Inspection Procedure 9: CVT Indicator Lamp System

CAUTION

Whenever the ECU is replaced, ensure that the 
communication circuit is normal.

OPERATION

The CVT indicator lamp detects the selector lever 
position (P, R, N, D, Ds, L), and displays it on the 
combination meter.

COMMENTS ON TROUBLE SYMPTOM

Connector(s) or wiring harness in the CAN bus lines 
between the engine-CVT-ECU and the combination 
meter, the power supply system to the 
engine-CVT-ECU, the combination meter, or the 
engine-CVT-ECU may be defective.

PROBABLE CAUSES

• The communication line is defective.

• Malfunction of combination meter

• Malfunction of the engine-CVT-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III CAN bus diagnostics

AC206895

Diagnosis connector

MB991827

MB991824

MB991910

AB

Use the M.U.T.-III to diagnose the CAN bus lines.

Q: Is the check result normal?

YES : 

Go to Step 2.

NO : 

Repair the CAN bus line (Refer to GROUP 
54D 

− Troubleshooting, Diagnosis Code 

Table 

P.54D-13

).

STEP 2. M.U.T.-III actuator test
Execute combination meter actuator test.

• Item A2: All shift position indicator lamps illumi-

nate.

• Item A3: All shift position indicator lamps go out.

OK: All shift position indicator lamps illumi-
nate or go out.

Q: Is the check result normal?

YES : 

Replace the engine-CVT-ECU.

NO : 

Go to Step 3.

STEP 3. Check the speedometer.
Use the M.U.T.-III to enter simulated vehicle speed.

OK: The speedometer shows that simulated 
vehicle speed.

Q: Is the check result normal?

YES : 

Replace the combination meter.

NO : 

Diagnose the combination meter (Refer to 
GROUP 54A 

− Combination Meter, 

Troubleshooting 

P.54A-31

).

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