Mitsubishi 380. Manual - part 378

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-52

STEP 6. Using diagnostic tool MB991958, check data list 
item 7: Transmission Fluid Temperature 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 the data reading mode.

• Item 7: Transmission Fluid Temperature Sensor.

• When the engine is cool: Diagnostic tool display is 

almost equal to the ambient temperature (atmo-
spheric temperature)

NOTE: Set diagnostic tool MB991958 to the Engine 
MPI data list reading mode for item number 5, Intake 
Air Temperature (IAT) Sensor and note the tempera-
ture measurement. When the engine is cool, the 
temperature should be almost equal to the ambient 
temperature (atmospheric temperature), and the IAT 
sensor measurement should be approximately the 
same as the Transmission Fluid Temperature Sen-
sor.

• When the engine is warm, at approximately running 

temperature: 70 

− 80°C.

(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-53

STEP 7. Measure the sensor output voltage at A/T-ECU 
connector 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) Turn the ignition switch to the "ON" position.

(4) Measure the voltage between terminal 6 and ground.

• When transmission fluid temperature is 20°C (68°F), 

voltage should measure between 3.8 and 4.0 volts.

• When transmission fluid temperature is 40°C (104°F), 

voltage should measure between 3.2 and 3.4 volts.

• When transmission fluid temperature is 80°C (176°F), 

voltage should measure between 1.7 and 1.9 volts.

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

Q: Is the measured voltage within the specified range?

YES : Go to Step 6.
NO :  Go to Step 8.

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

10DB081A

B-22  CONNECTOR:

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-54

STEP 8. 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 : Go to Step 9.
NO :  Repair or replace the damaged components. Refer to 

GROUP 00E, Harness Connector Inspection 

P.00E-2

.

STEP 9. Check the harness for a short circuit to ground 
between A/T-ECU connector B-22 terminal 6 and A/T 
control solenoid valve connector B-108 terminal 1.
Q: Is the harness wire in good condition?

YES : Go to Step 6.
NO :  Repair or replace the harness wire.

16DB564A

COVER

AIR

CLEANER

A/T

CONTROL

UNIT

CONNECTORS:  B-19, B-22

16DB564A

COVER

AIR

CLEANER

A/T

CONTROL

UNIT

CONNECTORS:  B-19, B-22

AC306322

CONNECTOR: B-108

B-108 (GR)

AC

TRANSMISSION
RANGE SWITCH

2

7

1

8

3

9

4

6

10

5

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-55

(P0715): Input Shaft Speed Sensor System

.

10DB083A

A-13 (GR)

CONNECTOR: A-13

1

4

7

8

2 3

5

13 14

17

15

12

16

11

10

9

6

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

10DB084A

CONNECTORS: C-214, 215

1
3 4

2
6

5

C-214

C-215

6

1
7

2

9

8

10

3

5

12

11

4

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