Mitsubishi Eclipse. Manual - part 818

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-281

LOGIC FLOW CHARTS (Monitor Sequence)

.

DTC SET CONDITIONS

Check Conditions

• Voltage of battery: 9 volts or more.

• Time after PCM turns on A/T control relay: 0.5 

second or more.

Judgement Criteria

• A/T control relay output voltage: 7 volts or less. 

(0.1 second)

• If DTC 54 (P1751) is set consecutively four times, 

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

.

OBD-II DRIVE CYCLE PATTERN
Start the engine, and keep the vehicle stopped in "P" 
range for 5 seconds.

.

AC205241

START

END

No

Malfunction

Yes

Good

No

Yes

No

Yes

No

Yes

No

Yes

Timer start

TCM turn on A/T 
control relay

Timer > 0.5 sec.

Voltage of battery > 9 V

Output voltage from 
control relay < 7 V

Continuous failure 
for 0.1 sec.

PCM

AB

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-282

TROUBLESHOOTING HINTS (The most likely 
causes for this code to be set are:)

• Malfunction of the A/T control relay

• Damaged harness or connector

• Malfunction of the PCM

DIAGNOSIS

Required Special Tool:

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

• MB991824: V.C.I.

• MB991827: MUT-III USB Cable

• MB991911: MUT-III Main Harness B

STEP 1. Using scan tool MB991958, check data list item 54: 
A/T Control Relay Output Voltage.

CAUTION

To prevent damage to scan tool MB991958, always turn the 
ignition switch to the "LOCK" (OFF) position before con-
necting or disconnecting scan tool MB991958.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Set scan tool MB991958 to data reading mode for item 54: 

A/T Control Relay Output Voltage.

• The voltage should equal battery positive voltage.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the measured voltage equal battery positive voltage?

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.00-6

.

NO :  Go to Step 2.

AC303127

AB

MB991911

16-PIN

MB991827

MB991824 

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

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STEP 2. Check the A/T control relay.
(1) Remove the A/T control relay from the engine compartment 

relay box connector A-17X.

(2) Using jumper wires, connect terminal 3 to the negative 

battery terminal, and terminal 2 to the positive battery 
terminal.

(3) Measure the resistance between terminals 1 and 4 of the 

A/T control relay.

• The resistance should measure less than 2 ohms.

• Disconnect the jumper wires. The resistance between 

terminals 1 and 4 should measure over limits (open cir-
cuit).

Q: Is the resistance measure less than 2 ohms when the 

relay is energized, and open circuit when the relay is 
de-energized?
YES : Go to Step 3.
NO :  Replace the A/T control relay.

STEP 3. Check A/T control relay socket A-17X in the 
engine compartment relay box for loose, corroded or 
damaged terminals, or terminals pushed back in the 
socket.
Q: Is the relay socket 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

.

AC102447AF

BATTERY

CONNECTOR: A-17X

A-17X

FRONT OF VEHICLE

AC203731

1 2
3 4

AB

A17X HARNESS CONNECTOR:
A/T CONTROL RELAY SIDE

FRONT OF VEHICLE

AC102447AF

BATTERY

CONNECTOR: A-17X

A-17X

FRONT OF VEHICLE

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-284

STEP 4. Measure the supply voltage at A/T control relay 
connector A-17X in the engine component relay box.
(1) Disconnect the A/T control relay.

(2) Measure the voltage between terminal 1 and ground.

• The measured voltage should equal battery positive 

voltage.

Q: Is the measured voltage equal to battery positive 

voltage?
YES : Go to Step 7.
NO :  Go to Step 5.

STEP 5. Check intermediate connector C-07 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 open circuit or short circuit 
to ground between A/T control relay connector A-17X 
terminal 1 in the engine component relay box and battery.
Q: Is the harness wire in good condition?

YES : Go to Step 17.
NO :  Repair or replace the harness wire.

AC102447AF

BATTERY

CONNECTOR: A-17X

A-17X

FRONT OF VEHICLE

1

2

3

4

AC203732

A17X HARNESS
CONNECTOR:
RELAY BOX SIDE

FRONT OF
VEHICLE

AB

AC001729AY

CONNECTOR: C-07

C-07

AC102447AF

BATTERY

CONNECTOR: A-17X

A-17X

FRONT OF VEHICLE