Mitsubishi 380. Manual - part 387

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-88

STEP 19. Using diagnostic tool MB991958, check data list 
item 6: Output Shaft Speed Sensor.

CAUTION

To prevent damage to diagnostic tool MB991958, always 
turn the ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting diagnostic tool 
MB991958.
(1) Connect diagnostic tool MB991958 to the data link 

connector.

(2) Start the engine.
(3) Set diagnostic tool MB991958 to data reading mode.

• Item 6: Output Shaft Speed Sensor.

• When driving at constant speed of 50 km/h, the dis-

play should be "1,900 

− 2,100 r/min" (Gear range: 

3rd gear).

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the sensor operating properly?

YES : It can be assumed that this malfunction is intermittent. 

Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunction 

P.00-14

.

NO :  Replace the A/T-ECU.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-89

Data List Item 19: Stoplamp Switch System

.

CIRCUIT OPERATION

• Battery positive voltage is supplied to the 

stoplamp switch (terminal 2).

• When the brake pedal is depressed, battery posi-

tive voltage is applied to the ENGINE-ECU con-
nector B-21 (terminal 18). 

.

DTC SET CONDITIONS

If the stoplamp switch is on for five minutes or more 
while driving above 50 km/h, or all of the stop light 
bulbs are blown, it is judged there is a short circuit or 
open circuit in the stoplamp switch. This causes Item 
19 to be set.

.

TROUBLESHOOTING HINTS (THE MOST 
LIKELY CAUSES FOR THIS CODE TO BE 
SET ARE:)

• Malfunction of the stoplamp switch

• Malfunction of stoplamp switch plunger

• Damaged harness or connector

Circuit drawings

• Refer to circuit diagrams GROUP-

90

• Refer to configuration diagrams GROUP-

80

• Refer to component locations GROUP-

70

DIAGNOSIS

Required Special Tool:

• MB991958: Diagnostic Tool (MUT-III Sub Assembly)

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991910: MUT-III Main Harness A

STEP 1. Check the brake pedal height.
Refer to GROUP 35A, On-vehicle Service 

− Brake Pedal 

Check and Adjustment 

P.35A-13

.

Q: Is the height adjusted properly?

YES : Go to Step 2.
NO :  Adjust the brake pedal to the proper height.

16DB400A

COVER

ENGINE

CONTROL

UNIT

AIR

CLEANER

10DB091A

CONNECTOR: C-30

2

1

3

4

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-90

STEP 2. Check the stoplamp switch plunger.
Refer to GROUP 54A, Rear combination light 

P.54A-161

.

Q: Is the stoplamp switch plunger in good condition?

YES : Go to Step 3.
NO :  Replace the stoplamp switch. Refer to GROUP 35A, 

Brake Pedal 

P.35A-24

.

STEP 3. Using diagnostic tool MB991958, check data list 
item 19: Stoplamp Switch.

CAUTION

To prevent damage to diagnostic tool MB991958, always 
turn the ignition switch to the "LOCK" (OFF) position 
before connecting or disconnecting diagnostic tool 
MB991958.
(1) Connect diagnostic tool MB991958 to the data link 

connector.

(2) Turn the ignition switch to the "ON" position.
(3) Set diagnostic tool MB991958 to the data reading mode.

• Item 19: Stoplamp Switch.

• When the brake pedal is depressed, the display on 

diagnostic tool MB991958 should be "ON."

• When the brake pedal is not depressed, the display 

on diagnostic tool MB991958 should be "OFF."

(4) Turn the ignition switch to the "LOCK" (OFF) position.

Q: Is the switch operating properly?

YES : It can be assumed that this malfunction may be 

intermittent. Refer to GROUP 00, How to Use 
Troubleshooting/Inspection Service Points 

− How to 

Cope with Intermittent Malfunction 

P.00-14

.

NO :  Go to Step 4.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-91

STEP 4. Measure the stoplamp switch power supply 
voltage at connector C-30 by backprobing.
(1) Remove the stoplamp switch from the mounting bracket.
(2) Do not disconnect connector C-30.

(3) Measure the voltage between terminal 2 and ground by 

backprobing.

• The voltage should measure battery positive voltage.

Q: Is the measured voltage battery positive voltage?

YES : Go to Step 7.
NO :   Go to step 5.

STEP 5. Check stoplamp switch connector C-30 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.
Q: Are the connector and terminals in good condition?

YES : Go to Step 6.
NO :  Repair or replace the damaged components. Refer to 

GROUP 00E, Harness Connector Inspection 

P.00E-2

.

STEP 6. Check the harness for damage between stoplamp 
switch connector C-30 terminal 2 and the power supply 
fuse.
Q: Is the harness wire in good condition?

YES : Go to Step 7.
NO :  Repair or replace the harness wire.

10DB091A

CONNECTOR: C-30

2

1

3

4

2

1

3

4

AC201487

C-30 HARNESS
CONNECTOR:
HARNESS SIDE

AG

10DB091A

CONNECTOR: C-30

2

1

3

4

10DB091A

CONNECTOR: C-30

2

1

3

4