Mitsubishi 380. Manual - part 379

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-56

CIRCUIT OPERATION

• The input shaft speed sensor generates 0 ⇔ 5 

volts pulse signal when the input shaft rotates. 
The pulse signal frequency increases with a rise 
in input shaft speed.

• The input shaft speed sensor is connected to the 

A/T-ECU connector B-22 (terminals 5 and 12) via 
the input shaft speed sensor connector (terminals 
1 and 2).

• The A/T-ECU detects the input shaft speed by the 

signal input to terminal 5.

• The input shaft speed sensor generates the pulse 

signal as the teeth of the underdrive clutch 
retainer pass the magnetic tip of the sensor.

.

DTC SET CONDITIONS

Check Conditions

• A/T range switch position: D, 5, 4, 3, 2, 1

• Output speed: 1,000 r/min or more.

• Transmission fluid temperature sensor voltage: 

4.5 volts or less.

Judgement Criteria

• Input shaft speed sensor signal: no signal 

change. (4 seconds)

• If (P0715) is set consecutively four times, the 

transmission is locked into 3rd gear or 2nd gear 
as a fail-safe measure, and the "N" range light 
flashes once per second.

.

OBD-II DRIVE CYCLE PATTERN

Start the engine, shift to 3rd gear or higher, and drive 
at 40 km/h or more for 10 seconds.

.

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

• Malfunction of the input shaft speed sensor

• Malfunction of the underdrive clutch retainer

• Damaged harness or connector

• Malfunction of the A/T-ECU

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

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-57

STEP 1. Using diagnostic tool MB991958, check A/T 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 :  Go to Step 2.

STEP 2. Measure the power supply voltage at the input 
shaft speed sensor connector B-109.
(1) Disconnect connector B-109 and measure at the harness 

side.

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

(3) Measure the voltage between terminal 3 and ground.

• The voltage should measure battery positive voltage.

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

Q: Is the measured voltage battery positive voltage?

YES : Go to Step 5.
NO :  Go to Step 3.

00DB076A

MB991910

DATA LINK

CONNECTOR

MB991824

MB991827

AC305354

TRANSMISSION
RANGE SWITCH

B-109 (GR)

AC  

CONNECTOR: B-109

1

3

2

3

1

2

AC210629

B-109 HARNESS
CONNECTOR:
COMPONENT SIDE

AC

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-58

STEP 3. Check intermediate connector A-13 and junction 
block connector C-214 for loose, corroded or damaged 
terminals, or terminals pushed back in the connector.
Q: Are the connectors and terminals in good condition?

YES : Go to Step 4.
NO :  Repair or replace the damaged components. Refer to 

GROUP 00E, Harness Connector Inspection 

P.00E-2

.

STEP 4. Check the harness for open circuit or short circuit 
to ground between the input shaft speed sensor connector 
B-109 terminal 3 and the junction block connector C-214 
terminal 12.
Q: Is the harness wire in good condition?

YES : Go to Step 5.
NO :  Repair or replace the harness wire.

10DB083A

A-13 (GR)

CONNECTOR: A-13

1

4

7

8

2 3

5

13 14

17

15

12

16

11

10

9

6

10DB085A

CONNECTOR: C-214

6

1
7

2

9

8

10

3

5

12

11

4

1314

AC305354

TRANSMISSION
RANGE SWITCH

B-109 (GR)

AC  

CONNECTOR: B-109

1

3

2

10DB085A

CONNECTOR: C-214

6

1
7

2

9

8

10

3

5

12

11

4

1314

AUTOMATIC TRANSMISSION DIAGNOSIS

AUTOMATIC TRANSMISSION

23A-59

STEP 5. Measure the A/T-ECU to speed sensor output 
voltage at the input shaft speed sensor connector B-109.
(1) Disconnect connector B-109 from the speed sensor and 

measure voltage at the harness side.

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

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

• The voltage should measure between 4.5 and 4.9 volts.

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

Q: Is the measured voltage between 4.5 and 4.9 volts?

YES : Go to Step 11.
NO :  Go to Step 6.

AC305354

TRANSMISSION
RANGE SWITCH

B-109 (GR)

AC  

CONNECTOR: B-109

1

3

2

3

1

2

AC210631

B-109 HARNESS
CONNECTOR:
COMPONENT SIDE

AC