Mitsubishi L200. Manual - part 282

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-35

PROBABLE CAUSES

• Malfunction of the A/T fluid temperature sensor

• Damaged harness wires and connectors

• Malfunction of the A/T-ECU

DIAGNOSIS

STEP 1. M.U.T.-III data list
Item 07: A/T fluid temperature sensor (Refer to Data 
List 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 2.

STEP 2. Connector check: B-15 A/T control 
solenoid valve assembly
Check for the contact with terminals.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Repair the defective connector.

STEP 3. Measure the voltage at A/T control 
solenoid valve assembly connector B-15.
(1) Disconnect the connector, and measure the 

voltage between terminal 1 and earth at the 
wiring harness side.

(2) Turn the ignition switch to the ON position.

OK: 4.5 

− 4.9 V

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Go to Step 6.

STEP 4. Measure the resistance at A/T control 
solenoid valve assembly connector B-15.
Disconnect the connector, and measure the resist-
ance between terminal 1 and 2 at the sensor side.

OK: 

• 16.7 − 20.5 kΩ (at 0°C)

• 7.3 − 8.9 kΩ (at 20°C)

• 3.4 − 4.2 kΩ (at 40°C)

• 1.9 − 2.2 kΩ (at 60°C)

• 1.0 − 1.2 kΩ (at 80°C)

• 0.57 − 0.69 kΩ (at 100°C)

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Replace the A/T fluid temperature sensor.

STEP 5. M.U.T.-III data list
Item 07: A/T fluid temperature sensor (Refer to Data 
List Table 

P.23A-103

). 

Q: Is the check result normal?

YES : 

Intermittent malfunction (Refer to GROUP 

00 

− How to Cope with Intermittent 

Malfunction ).

NO : 

Replace the A/T-ECU.

STEP 6. Measure the voltage at A/T-ECU 
connector C-12.
(1) Connect A/T control solenoid valve assembly 

connector B-15.

(2) Turn the ignition switch to the ON position.
(3) Measure the voltage between A/T-ECU 

connector C-12 terminal No.44 and earth. 

OK: 

• 3.8 − 4.0 V (at 20°C)

• 3.2 − 3.4 V (at 40°C)

• 1.7 − 1.9 V (at 80°C)

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Go to Step 7.

STEP 7. Connector check: B-10 intermediate 
connector, C-12 A/T-ECU connector
Check for the contact with terminals.

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

Repair the defective connector.

STEP 8. Check the harness between A/T control 
solenoid valve assembly connector B-15 terminal 
No.1 and A/T-ECU connector C-12 terminal No.44.
Check the output line for short-circuited or open cir-
cuit.

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the wiring harness.

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-36

Code No.P1766 (P0715) Input shaft speed sensor system

A/T-ECU

INPUT SHAFT
SPEED SENSOR 

IGNITION
SWITCH (IG1)

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

Input Shaft Speed Sensor System Circuit

AC903904

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

AC510056AD

Harness side

B-10 (B)

Connector: B-10

AC510056AC

Harness side

B-11 (B)

Connector: B-11

AC510056AE

B-17 (B)

Connector: B-17

Harness side

AC510057

Harness side

A/T-ECU

C-12

AB

Connector: C-12

A/T-ECU

<RHD>

<LHD>

AC509930AG

Connector: C-34 <RHD>

C-34

Harness side

AC509613AG

Connector: C-52 <LHD>

C-52

Harness side

AC509934

Connectors: C-207, C-208 <LHD>

Junction block (Front view)

C-208

CX

Harness side

C-207

AC509936

Connectors: C-207, C-208 <RHD>

Harness side

C-208

C-207

BZ

Junction block 
(Front view)

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-37

OPERATION
The input shaft speed sensor detects the speed of 
the underdrive clutch retainer, and sends the infor-
mation to the A/T-ECU as a pulse signal.

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-38

DIAGNOSIS CODE SET CONDITIONS
The diagnosis code No.P1766 (P0715) is set if the 
input shaft speed sensor does not send a pulse sig-
nal for one second or more while the 3rd gears are 
engaged and the vehicle speed is 40 km/h or more 
(the output shaft speed sensor speed is 1,000 r/min 
or more).
If the code No.P1766 (P0715) is set four times, the 
transmission will be fixed in 3rd gear as a fail-safe 
measure. However, the transmission can be down-
shifted to 2nd gear by operating the selector lever. 

PROBABLE CAUSES

• Malfunction of input shaft speed sensor

• Malfunction of underdrive clutch retainer

• Damaged harness wires and connectors

• Malfunction of the A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list
Item 05: Input shaft speed sensor (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 2.

STEP 2. Connector check: B-17 input shaft speed 
sensor connector
Check for the contact with terminals.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Repair the defective connector.

STEP 3. Measure the resistance at input shaft 
speed sensor connector B-17.
Disconnect the connector, and measure the resist-
ance between terminal 1 and earth at the wiring har-
ness side.

OK: Continuity (Less than 2 

Ω)

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Go to Step 4.

STEP 4. Measure the voltage at A/T-ECU 
connector C-12.
(1) Connect input shaft speed sensor connector B-

17.

(2) Turn the ignition switch to the ON position.

(3) Measure the voltage between A/T-ECU 

connector C-12 terminal No.43 and earth.

OK: 0.5 V or less

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Go to Step 5.

STEP 5. Connector check: C-12 A/T-ECU 
connector
Check for the contact with terminals.

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the defective connector.

STEP 6. M.U.T.-III data list
Item 05: Input shaft speed sensor (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 : 

Replace the A/T-ECU.

STEP 7. Connector check: B-11 intermediate 
connector, C-12 A/T-ECU connector
Check for the contact with terminals.

Q: Is the check result normal?

YES : 

Go to Step 8.

NO : 

Repair the defective connector.

STEP 8. Check the harness between input shaft 
speed sensor connector B-17 terminal No.1 and 
A/T-ECU connector C-12 terminal No.43.
Check the earth line for open circuit.

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the wiring harness.

STEP 9. Measure the voltage at input shaft speed 
sensor connector B-17.
(1) Disconnect the connector, and measure the 

voltage between terminal 3 and earth at the 
wiring harness side.

(2) Turn the ignition switch to the ON position.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 12.

NO : 

Go to Step 10.