Mitsubishi L200. Manual — part 290

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-67

(3) Check the diagnosis code.

Q: Is the diagnosis code set?

YES :

Go to Step 7.

NO :

The inspection is complete.

STEP 7. Check the A/T internal clutch and brake,
and then recheck the diagnosis code.
(1) Check the following clutches or brakes according

to the output diagnosis codes, replace if

necessary.

• If diagnosis code P1779, P1780, P1781,

P1782 are set individually or in a group,
replace the underdrive clutch.

• If diagnosis code P1781, P1782, P1783 are

set individually or in a group, replace the over-
drive clutch.

• If diagnosis code P1784 is set, replace the

reverse clutch.

• If diagnosis code P1779, P1784 are set indi-

vidually or in a group, replace the low-reverse
brake.

• If diagnosis code P1780, P1783 are set indi-

vidually or in a group, replace the second
brake.

• If diagnosis code P1782, P1783 are set indi-

vidually or in a group, replace the direct
clutch.

• If diagnosis code P1779, P1780, P1781,

P1784 are set individually or in a group,
replace the reduction brake.

• If diagnosis code P1779 is set, replace the

one-way clutch (OWC-L).

• If diagnosis code P1779, P1780, P1781 are

set individually or in a group, replace the one-
way clutch (OWC-D).

(2) Test drive the vehicle.
(3) Check the diagnosis code.

Q: Is the diagnosis code set?

YES :

Eliminate the cause of the noise.

NO :

The inspection is complete.

Code No.P1786 Damper clutch system (stuck off)

OPERATION
The A/T-ECU engages and disengages the damper
clutch (incorporated in the torque converter) by oper-
ating the DCC solenoid valve in response to driving
conditions.

DIAGNOSIS CODE SET CONDITIONS
If the damper clutch solenoid valve drive duty ratio is
100% for a continuous period of 4 seconds or more
when the damper clutch starts operating, diagnosis
code No.P1786 is output.

PROBABLE CAUSES

• Malfunction of input shaft speed sensor

• Damaged harness wires and connectors

• Malfunction of the A/T-ECU

• Malfunction of damper clutch solenoid valve

• Malfunction of valve body assembly

• Malfunction of torque converter

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code
If diagnosis code P1786 is output, the input shaft
speed sensor may be defective.

Q: Is diagnosis code P1766 (P0715) set?

YES :

Refer to diagnosis code P1766 (P0715):

Input shaft speed sensor system

P.23A-36

.

NO :

Go to Step 2.

STEP 2. M.U.T.-III diagnosis code
If diagnosis code P1786 is output, the damper clutch
solenoid valve may be defective.

Q: Is diagnosis code P1778 (P0740) set?

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-68

YES :

Refer to diagnosis code P1778 (P0740):

Damper clutch solenoid valve system

P.23A-62

.

NO :

Go to Step 3.

STEP 3. M.U.T.-III data list

• Item 17: Damper clutch solenoid valve duty ratio

(Refer to data list reference table

P.23A-103

).

• Item 10: Damper clutch slip amount (Refer to

data list reference table

P.23A-103

).

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Go to Step 4.

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

P.23A-120

.)

OK: Refer to Hydraulic Pressure Test

P.23A-

120

.

Q: Is the check result normal?

YES :

Go to Step 6.

NO :

Go to Step 5.

STEP 5. Adjust the line pressure and recheck the
diagnosis code.
(1) Adjust the line pressure (Refer to

P.23A-129

).

(2) Test drive the vehicle.

(3) Check the diagnosis code.

Q: Is the diagnosis code set?

YES :

Go to Step 7.

NO :

The inspection is complete.

STEP 6. Replace the A/T-ECU and then recheck
the diagnosis code.
(1) Replace the A/T-ECU.
(2) Test drive the vehicle.
(3) Check the diagnosis code.

Q: Is the diagnosis code set?

YES :

Go to Step 7.

NO :

The inspection is complete.

STEP 7. Disassemble, clean and assemble the
valve body and recheck the diagnosis code.
(1) Check the mounting 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) Check the diagnosis code.

Q: Is the diagnosis code set?

YES :

Check the torque converter and replace it if

necessary.

NO :

The inspection is complete.

Code No.P1787 Damper clutch system (stuck on)

OPERATION
Refer to

P.23A-67

.

DIAGNOSIS CODE SET CONDITIONS
If the damper clutch control remains engaged for a
continuous period of ten seconds or more when the
A/T-ECU is attempting to disengage the damper
clutch control, diagnosis code No.P1787 is output.

PROBABLE CAUSES

• Damaged harness wires and connectors

• Malfunction of the A/T-ECU

• Malfunction of damper clutch solenoid valve

• Malfunction of valve body assembly

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III diagnosis code
If diagnosis code P1787 is output, the damper clutch
solenoid valve may be defective.

Q: Is diagnosis code P1778 (P0740) set?

YES :

Refer to diagnosis code P1778 (P0740):

Damper clutch solenoid valve system

P.23A-62

.

NO :

Go to Step 2.

STEP 2. M.U.T.-III data list
Item 10: Damper clutch slip amount (Refer to data
list reference table

P.23A-103

).

Q: Is the check result normal?

YES :

Intermittent malfunction (Refer to GROUP

00

− How to Cope with Intermittent

Malfunction .)

NO :

Go to Step 3.

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-69

STEP 3. Replace the A/T-ECU and then recheck
the diagnosis code.
(1) Replace the A/T-ECU.
(2) Test drive the vehicle.
(3) Check the diagnosis code.

Q: Is the diagnosis code set?

YES :

Go to Step 4.

NO :

The inspection is complete.

STEP 4. Disassemble, clean and assemble the
valve body and recheck the diagnosis code.
(1) Check the mounting 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) Check the diagnosis code.

Q: Is the diagnosis code set?

YES :

Check the torque converter and replace it if

necessary.

NO :

The inspection is complete.

Code No.P1788 (P1751) A/T control relay system

AC903910

23

FUSIBLE
LINK

RELAY
BOX

A/T
CONTROL
RELAY

A/T-ECU

Wire colour code
B : Black LG : Light green G : Green L : Blue W : White Y : Yellow SB : Sky blue
BR : Brown O : Orange GR : Grey R : Red P : Pink V : Violet PU : Purple

IGNITION
SWITCH (IG1)

A/T Control Relay System Circuit

<4A/T, 5A/T-LHD>
<5A/T-RHD>

SOLENOID
VALVE
POWER SOURCE

AC510163

AG

Connector: A-19X

Relay box side

A-19X

AC509975AO

Harness side

A-115

Connector: A-115

AC510057

A/T-ECU

C-19

AD

Connector: C-19

A/T-ECU

<RHD>

<LHD>

Harness side

AC510057

Harness side

A/T-ECU

C-20

AC

Connector: C-20

A/T-ECU

<RHD>

<LHD>

AC509930AG

Connector: C-34 <RHD>

C-34

Harness side

AC509613AG

Connector: C-52 <LHD>

C-52

Harness side

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-70