Mitsubishi Montero (2004+). Manual - part 901

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

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CIRCUIT OPERATION

• The A/T control relay supplies battery positive 

voltage to the solenoid valve assembly (terminals 
9 and 10).

• The solenoid valve closes when energized (on), 

and opens when not energized (off). The PCM 
energizes the solenoid valve based on input data 
from sensors such as the APP Sensor, Transmis-
sion Range Switch, Stoplight Switch, Vehicle 
Speed Sensor, Input Shaft Speed Sensor, Output 
Shaft Speed Sensor, and Transmission Fluid 
Temperature Sensor.

• The PCM provides the ground to energize the 

solenoid. The amount of time that the circuit is 
grounded is displayed on scan tool MB991958 in 
percent.

• When the solenoid is energized or de-energized, 

fluid passes through the valve body and transmis-
sion passages to apply and release components.

.

DESCRIPTIONS OF MONITOR METHODS
If solenoid terminal voltage is below specified value 
when shift control is not in progress, PCM judges 
that low-reverse solenoid has a failure.

.

MONITOR EXECUTION
Continuous

.

MONITOR EXECUTION CONDITIONS (OTHER 
MONITOR AND SENSOR)

Other Monitor (There is no temporary DTC stored 

in memory for the item monitored below)

• DTC 41 (P0731): 1st gear incorrect ratio

• DTC 42 (P0732): 2nd gear incorrect ratio

• DTC 43 (P0733): 3rd gear incorrect ratio

• DTC 44 (P0734): 4th gear incorrect ratio

• DTC 45 (P0735): 5th gear incorrect ratio

• DTC 46 (P0736): Reverse gear incorrect ratio

• DTC 36 (P0743): Torque converter clutch sole-

noid malfunction

• DTC 32 (P0758): Underdrive solenoid malfunc-

tion

• DTC 33 (P0763): Second solenoid malfunction

• DTC 34 (P0768): Overdrive solenoid malfunction

• DTC 35 (P0773): Reduction solenoid malfunction

• DTC 54 (P1751): A/T control relay malfunction

Sensor (The sensor below is determined to be 

normal)

• Torque converter clutch solenoid

• Underdrive solenoid

• Second solenoid

• Overdrive solenoid

• Reduction solenoid

• A/T control relay

.

AUTOMATIC TRANSMISSION DIAGNOSIS

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AUTOMATIC TRANSMISSION

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LOGIC FLOW CHARTS (Monitor Sequence)

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DTC SET CONDITIONS

Check Conditions

• Solenoid status: either solid ON or OFF.

• Shift status: in-gear.

• Voltage of battery: 10 volts or more.

Judgement Criteria

• Solenoid voltage: 3 volts or less. (0.3 second)

• If DTC 31 (P0753) is set consecutively four times, 

the transmission 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.

.

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

• Malfunction of low-reverse solenoid valve

• Damaged harness, connector

• Malfunction of the PCM

AC205281

Good

Malfunction

END

START

In-gear?

Shift solenoid-A is in ON 
or OFF steady state

Voltage of battery > 10 V

Solenoid circuit 
voltage < 3 V

Continuous failure 
for 0.3 sec.

Yes

No

Yes

No

Yes

No

Yes

No

Yes

No

Low-reverse solenoid valve
is in ON or OFF steady state

AB

AUTOMATIC TRANSMISSION DIAGNOSIS

TSB Revision

AUTOMATIC TRANSMISSION

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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 actuator test 
item 01: Low-Reverse Solenoid Valve.

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 the actuator test mode.

• Item 01: Low-Reverse Solenoid Valve.

• An audible clicking or buzzing should be heard when 

the low-reverse solenoid valve is energized.

(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is the solenoid valve 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 Malfunctions 

P.00-6

.

NO :  Go to Step 2.

AC307591 AC

MB991911

MB991824

MB991827

AC307591

DATA LINK

CONNECTOR

AUTOMATIC TRANSMISSION DIAGNOSIS

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STEP 2. Using scan tool MB991958, read the A/T 
diagnostic trouble code.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Check for A/T diagnostic trouble code.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Is DTC 54 set? (DTC 54 may be set along with multiple 

DTCs).
YES : Refer to 

P.23A-277

 DTC 54: A/T Control Relay 

System.

NO :  Go to Step 3.

STEP 3. Using scan tool MB991958, read the A/T 
diagnostic trouble code.
(1) Connect scan tool MB991958 to the data link connector.
(2) Turn the ignition switch to the "ON" position.
(3) Check for A/T diagnostic trouble code.
(4) Turn the ignition switch to the "LOCK" (OFF) position.
Q: Are DTC 35 and DTC 36 set? (Multiple DTCs may be set).

YES : Go to Step 8.
NO :  Go to Step 4.

AC307591 AC

MB991911

MB991824

MB991827

AC307591

DATA LINK

CONNECTOR

AC307591 AC

MB991911

MB991824

MB991827

AC307591

DATA LINK

CONNECTOR