Mitsubishi Galant. Manual — part 400

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-67

•

The A/T fluid temperature sensor is an NTC
(negative temperature coefficient) type of resistor.
When the A/T fluid temperature rises, the
resistance decreases.

•

The A/T fluid temperature sensor output voltage
rises when the resistance increases, and drops
when the resistance decreases.

DTC SET CONDITIONS
If the A/T fluid temperature sensor output voltage is
4.5 volts or more after driving for 10 minutes or more
(if the A/T fluid temperature does not increase), there
is an open circuit in the A/T fluid temperature sensor
and diagnostic trouble code number "15" is output.

TROUBLESHOOTING HINTS (The most likely

causes for this code to be set:)

•

Malfunction of the A/T fluid temperature sensor
circuit

•

Damaged harness, connector

•

Malfunction of the PCM

DIAGNOSIS

Required Special Tool:
MB991502: Scan Tool (MUT-II)

STEP 1. Using scan tool MB991502, check data list item 15:
A/T Fluid Temperature Sensor.

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to "LOCK" (OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to the data link connector.
(2) Start the engine.
(3) Set scan tool MB991502 to data reading mode for item 15:

A/T Fluid Temperature Sensor.

•

At cool condition: Almost equal to the ambient
temperature (atmospheric temperature)

•

At warm condition: 70 to 80

°

C (158 to 176

°

F)

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

Q: Is the sensor operating properly?

YES : This malfunction is intermittent. Refer to GROUP 00,

How to Use Troubleshooting/Inspection Service
Points

−

How to Cope with Intermittent Malfunction

P.00-8

.

NO : Go to Step 2.

AC003081AC

MB991502

DATA LINK
CONNECTOR

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-68

STEP 2. Check the ground voltage at PCM connector C-40
by backprobing.
(1) Do not disconnect connector C-40.
(2) Turn the ignition switch to "ON" position.

(3) Measure the voltage between terminal 57 and ground by

backprobing.

•

Voltage should be 0.5 volt or less.

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

Q: Is the voltage normal?

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

STEP 3. Check connector C-40 at PCM for damage.
Q: Is the connector in good condition?

YES : Go to Step 4.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

.

AC004197

PCM

AD

CONNECTOR: C-40

AC001791

C-40 CONNECTOR
HARNESS SIDE VIEW

AE

AC004197

PCM

AD

CONNECTOR: C-40

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-69

STEP 4. Using scan tool MB991502, check data list item 15:
A/T Fluid Temperature Sensor.

CAUTION

To prevent damage to scan tool MB991502, always turn the
ignition switch to "LOCK" (OFF) position before
connecting or disconnecting scan tool MB991502.
(1) Connect scan tool MB991502 to data link connector.
(2) Start the engine.
(3) Set scan tool MB991502 to the data reading mode for item

15: A/T Fluid Temperature Sensor.

•

At cool condition: Almost equal to the ambient
temperature (atmospheric temperature)

•

At warm condition: 70 to 80

°

C (158 to 176

°

F)

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

Q: Is the sensor operating properly?

YES : This malfunction is intermittent. Refer to GROUP 00,

How to Use Troubleshooting/Inspection Service
Points

−

How to Cope with Intermittent Malfunction

P.00-8

.

NO : Replace the PCM.

STEP 5. Check the sensor output voltage at PCM
connector C-42 by backprobing.
(1) Do not disconnect connector C-42.
(2) Turn the ignition switch to "ON" position.

(3) Measure the voltage between terminal 124 and ground by

backprobing.

•

When A/T fluid temperature is 20

°

C (68

°

F), voltage

should be between 3.8 and 4.0 volts.

•

When A/T fluid temperature is 40

°

C (104

°

F), voltage

should be between 3.2 and 3.4 volts.

•

When A/T fluid temperature is 80

°

C (176

°

F), voltage

should be between 1.7 and 1.9 volts.

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

Q: Is the voltage normal?

YES : Go to Step 6.
NO : Go to Step 7.

AC003081AC

MB991502

DATA LINK
CONNECTOR

AC004197

PCM

AF

CONNECTOR: C-42

AC001792

C-42 CONNECTOR
HARNESS SIDE VIEW

AE

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-70

STEP 6. Check connector C-42 at PCM for damage.
Q: Is the connector in good condition?

YES : Go to Step 4.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

.

STEP 7. Check connectors C-40 and C-42 at PCM and B-38
at A/T control solenoid valve assembly for damage.
Q: Are the harness connectors in good condition?

YES : Go to Step 8.
NO : Repair or replace it. Refer to GROUP 00E, Harness

Connector Inspection

P.00E-2

.

AC004197

PCM

AF

CONNECTOR: C-42

AC004197

PCM

C-40

C-42

CONNECTORS: C-40, C-42

AE

ACX02479

CONNECTOR: B-38

AF