Mitsubishi L200. Manual - part 297

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-95

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list
Item 26: Overdrive switch (Refer to data list refer-
ence 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. Check the overdrive switch.
Refer to 

P.23A-132

.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Replace the high/low detection switch.

STEP 3. Measure the voltage at overdrive switch 
connector C-129.
(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 6.

NO : 

Go to Step 4.

STEP 4. Connector check: C-129 overdrive 
switch connector, C-208 J/B connector
Check for the contact with terminals.

Q: Is the check result normal?

YES : 

Go to Step 5.

NO : 

Repair the defective connector.

STEP 5. Check the harness between overdrive 
switch connector C-129 terminal No.3 and J/B 
connector C-208 terminal No.2.
Check the power supply line for short or open circuit.

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Repair the wiring harness.

STEP 6. Measure the voltage at A/T-ECU 
connector C-20.
(1) Disconnect high/low detection switch connector 

C-129.

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

connector C-20 terminal No.57 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Go to Step 8.

STEP 7. M.U.T.-III data list
Item 26: Overdrive switch (Refer to data list refer-
ence 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 8. Connector check: C-129 overdrive 
switch connector, C-52 <LHD>or C-34 <RHD> 
intermediate connector, C-20 A/T-ECU connector
Check for the contact with terminals.

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Repair the defective connector.

STEP 9. Check the harness between overdrive 
switch connector C-129 terminal No.4 and A/T-
ECU connector C-20 terminal No.57.
Check the power supply line for short or open circuit.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Repair the wiring harness.

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-96

Inspection Procedure 17: 4LLc operation detection switch system <4WD>

AC903912

A/T-ECU

4LLc
OPERATION
DETECTION 
SWITCH

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

4LLc Operation Detection Switch System Circuit

AC509975AO

Harness side

A-115

Connector: A-115

AC510056AH

B-05

Connector: B-05

Harness side

AC510057

A/T-ECU

C-19

AD

Connector: C-19

A/T-ECU

<RHD>

<LHD>

Harness side

AC509611CW

Harness side

Connector: C-29 <LHD>

C-29

AC509930BI

Connector: C-29 <RHD>

Harness side

C-29

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-97

OPERATION

• A battery voltage is applied to the 4LLc operation 

detection switch output terminal (terminal 1) from 
the A/T-ECU (terminal 9) via the resistance in the 
unit.

• The 4LLc operation detection switch is grounded 

through the transfer case to the vehicle body.

COMMENTS ON TROUBLE SYMPTOM
If the transmission shifts to 4th gear when the trans-
fer lever is in the 4L position, the cause is probably a 
malfunction of the 4LLc operation detection switch.

PROBABLE CAUSES

• Malfunction of the 4LLc operation detection 

switch

• Damaged harness wires and connectors

• Malfunction of the A/T-ECU

DIAGNOSIS PROCEDURE

STEP 1. M.U.T.-III data list
Item 31: 4LLc operation detection switch (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. Check the 4LLc operation detection 
switch.
Refer to 

P.23A-119

.

Q: Is the check result normal?

YES : 

Go to Step 3.

NO : 

Replace the 4LLc operation detection 
switch.

STEP 3. Measure the voltage at 4LLc operation 
detection switch connector B-05.
(1) Disconnect the connector, and measure the 

resistance between terminal 1 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 4.

NO : 

Go to Step 5.

STEP 4. M.U.T.-III data list
Item 31: 4LLc operation detection switch (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 5. Measure the voltage at A/T-ECU 
connector C-19.
(1) Disconnect 4LLc operation detection switch 

connector B-05.

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

connector C-19 terminal No.9 and earth.

OK: System voltage

Q: Is the check result normal?

YES : 

Go to Step 6.

NO : 

Go to Step 8.

STEP 6. Connector check: B-05 4LLc operation 
detection switch connector, A-115 and C-29 
intermediate connector, C-19 A/T-ECU connector
Check for the contact with terminals.

Q: Is the check result normal?

YES : 

Go to Step 7.

NO : 

Repair the defective connector.

TROUBLESHOOTING

AUTOMATIC TRANSMISSION

23A-98

STEP 7. Check the harness between 4LLc 
operation detection switch connector B-05 
terminal No.1 and A/T-ECU connector C-19 
terminal No.9.
Check the power supply line for open circuit.

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the wiring harness.

STEP 8. Connector check: B-05 4LLc operation 
detection switch connector, A-115 and C-29 
intermediate connector, C-19 A/T-ECU connector
Check for the contact with terminals.

Q: Is the check result normal?

YES : 

Go to Step 9.

NO : 

Repair the defective connector.

STEP 9. Check the harness between 4LLc 
operation detection switch connector B-05 
terminal No.1 and A/T-ECU connector C-19 
terminal No.9.
Check the power supply line for short circuit.

Q: Is the check result normal?

YES : 

Go to Step 4.

NO : 

Repair the wiring harness.