Mitsubishi 380. Manual - part 382

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-68

STEP 14. Check the harness for open circuit or damage 
between A/T-ECU connector B-22 terminal 12 and input 
shaft speed sensor connector B-109 terminal 1.
Q: Is the harness wire in good condition?

YES : Go to Step 16.
NO :  Repair or replace the harness wire.

STEP 15. Check A/T-ECU connector B-22 for loose, 
corroded or damaged terminals, or terminals pushed back 
in the connector.
Q: Are the connector and terminals in good condition?

YES : Replace the A/T-ECU.
NO :  Repair or replace the damaged components. Refer to 

GROUP 00E, Harness Connector Inspection 

P.00E-2

.

16DB564A

COVER

AIR

CLEANER

A/T

CONTROL

UNIT

CONNECTORS:  B-19, B-22

AC305354

TRANSMISSION
RANGE SWITCH

B-109 (GR)

AC  

CONNECTOR: B-109

1

3

2

16DB564A

COVER

AIR

CLEANER

A/T

CONTROL

UNIT

CONNECTORS:  B-19, B-22

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-69

STEP 16. Using the oscilloscope, check the input shaft 
speed sensor waveform at A/T-ECU connectors B-22 by 
using check harness special tool MB992045.
(1) Disconnect all the connectors from the A/T-ECU.

(2) Connect special tool MB992045 (check harness) between 

the A/T-ECU and the body-side harness connector.

(3) Connect an oscilloscope probe to A/T-ECU connector B-22 

terminal 5 and to 12.

(4) Start the engine and drive the vehicle at constant speed of 

50 km/h  (Gear range: 3rd gear).

16DB564A

COVER

AIR

CLEANER

A/T

CONTROL

UNIT

CONNECTORS:  B-19, B-22

10DB161A

A/T-ECU CHECK HARNESS
    MB992045

A/T-ECU

A/T-ECU CHECK 
HARNESS
CONNECTORS

10DB088A

B-22 CONNECTOR: 

OSCILLO-
SCOPE

PROBE

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-70

(5) Check the input shaft speed sensor waveform.

• The input shaft speed sensor waveform should show a 

pattern similar to the illustration. The maximum value 
should be 4.8 volts or more and the minimum value 0.8 
volt or less. The output waveform should not contain 
electrical noise.

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

Q: Is the waveform normal?

YES : Go to Step 19.
NO :  Go to Step 17.

STEP 17. Replace the input shaft speed sensor.
(1) Replace the input shaft speed sensor. Refer to GROUP 

23B, Transmission 

P.23B-13

.

(2) Test drive the vehicle.
(3) Check for A/T diagnostic trouble code.

Q: Is A/T (P0715) set?

YES : Go to Step 18.
NO :  The procedure is complete.

STEP 18. Replace the underdrive clutch retainer.
(1) Replace the underdrive clutch retainer. Refer to GROUP 

23B, Underdrive Clutch and Input Shaft 

P.23B-46

.

(2) Test drive the vehicle.
(3) Check for A/T diagnostic trouble code.

Q: Is A/T (P0715) set?

YES : An A/T DTC may have set due to external radio 

frequency interference (RFI) possibility caused by 
cellular phone activity, or aftermarket components 
installed on the vehicle.

NO :  The procedure is complete.

ACX02131

NORMAL WAVEFORM

AD

(V)

5

0

AC305354AD

INPUT SHAFT
SPEED SENSOR

TRANSMISSION 
RANGE SWITCH

AC001836AB

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-71

STEP 19. Using diagnostic tool MB991958, check data list 
item 5: Input 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 5: Input Shaft Speed Sensor.

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

play should be "2,000 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