Mitsubishi Eclipse. Manual - part 784

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-145

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

23B, Transaxle 

P.23B-10

.

(2) Test drive the vehicle.
(3) Check for A/T diagnostic trouble code.
Q: Is A/T DTC 23 set?

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

STEP 18. Replace the transfer drive gear or driven gear.
(1) Replace the transfer drive gear or driven gear. Refer to 

GROUP 23B, Transaxle 

P.23B-10

, Output Shaft 

P.23B-68

.

(2) Test drive the vehicle.
(3) Check for A/T diagnostic trouble code.
Q: Is A/T DTC 23 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.

STEP 19. Using scan tool MB991958, check data list item 
23: Output Shaft Speed Sensor.

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) Start the engine.
(3) Set scan tool MB991958 to data reading mode for item 23: 

Output Shaft Speed Sensor.

• When driving at constant speed of 50 km/h (31 mph), 

the display should be "1,600 

− 1,900 r/min." <2.4L 

Engine>, "1,300 

− 1,600 r/min." <3.0L Engine> (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.00-6

.

NO :  Replace the PCM.

AC001837AD

OUTPUT SHAFT
SPEED SENSOR

AC002221AC

TRANSFER
DRIVE GEAR

TRANSFER
DRIVEN GEAR

AC303127

AB

MB991911

16-PIN

MB991827

MB991824 

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-146

DTC 26: Stoplight Switch System

AC106632AB

Stoplight Switch System Circuit

AC001729

C-03

CONNECTOR: C-03

AV

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-147

.

CIRCUIT OPERATION

• Battery positive voltage is supplied to the stop-

light switch (terminal 2).

• When the brake pedal is depressed, battery posi-

tive voltage is applied to the PCM (terminal 123). 

.

DTC SET CONDITIONS
If the stoplight switch is on for five minutes or more 
while driving above 50 km/h (31 mph), or all of the 
stoplight bulbs are blown, it is judged there is a short 
circuit or open circuit in the stoplight switch. This 
causes DTC 26 to be set.

.

AC106611AB

CONNECTOR: C-28

C-28

AC001657

CONNECTOR: C-61 <2.4L ENGINE> OR
C-63 <3.0L ENGINE>

PCM

BC

C-61 <2.4L ENGINE> OR C-63 <3.0L ENGINE>

AC106616 AB

CONNECTOR BLOCK (LH)

CONNECTOR: C-89

C-89

AUTOMATIC TRANSAXLE DIAGNOSIS

TSB Revision

AUTOMATIC TRANSAXLE

23A-148

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

• Malfunction of the stoplight switch circuit

• Malfunction of stoplight valve

• 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. Check the stoplight turning on or off.
Check that the stoplights are turned on when the brake pedal is 
depressed, or turned off when released.
Q: Is the operating properly?

YES : Go to Step 9.
NO :  Go to Step 2.

STEP 2. Check the brake pedal height.
Refer to GROUP 35A, On-vehicle Service 

− Brake Pedal 

Check and Adjustment 

P.35A-17

.

Q: Is the height adjusted properly?

YES : Go to Step 3.
NO :  Adjust the brake pedal to the proper height.

STEP 3. Using scan tool MB991958, check data list item 26: 
Stoplight Switch.

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 26: 

Stoplight Switch.

• When the brake pedal is depressed, the display on the 

scan tool MB991958 should be "ON."

• When the brake pedal is not depressed, the display on 

the scan tool MB991958 should be "OFF."

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the switch operating properly?

YES : If can be assumed that this malfunction may be 

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 4.

AC303127

AB

MB991911

16-PIN

MB991827

MB991824