1998 MITSUBISHI MONTERO Service Manual

this information to control solenoids on transmission valve body. TCM
controls transmission shifting and torque converter lock-up.
TCM contains a self-diagnostic system, which will store
Diagnostic Trouble Codes (DTC) if failure or problem exists in
electronic control system. DTC can be retrieved to determine problem
area. See SELF-DIAGNOSTIC SYSTEM. TCM is located under left side of
instrument panel, left of steering column. See Fig. 1.
TCM INPUT DEVICES
Brakelight Switch Signal
Brakelight switch delivers input signal to TCM, indicating
vehicle braking. Brakelight switch is located on brake pedal support.
Cruise Control Electronic Control Unit (ECU)
Cruise control ECU delivers an input signal to control
overdrive operation in accordance with vehicle speed when cruise
control is operating. When in overdrive with cruise control on, if
vehicle speed drops 2 MPH less than the set speed, overdrive is
released to prevent reduction in vehicle speed. Once vehicle speed is
more than the set speed, overdrive function is resumed. If coolant
temperature is low, transmission will not shift into overdrive. Cruise
control ECU is located below center A/C vent, behind temperature
control panel on Montero. On Montero Sport, cruise control ECU is
located behind driver's kick panel.
Engine Coolant Temperature Sensor (ECT) Signal
Engine coolant temperature sensor delivers input signal to
TCM, indicating engine coolant temperature. Coolant temperature sensor
is located on engine.
Input & Output Shaft Speed Sensors
Sensors are magnetic pick-ups that monitor input and output
shaft speeds. AC waveforms are input to TCM by sensors. Sensors are
located on front and rear side of transmission case.
OD Switch Signal
The OD switch provides an input signal to TCM to indicate
when overdrive is selected by operator. When OD switch is depressed to
ON position, transmission will shift into 4th gear when shift lever is
in "D" position, and OD OFF light on instrument panel will go off.
When OD switch is released to OFF position, transmission will shift
into 3rd gear, and OD OFF light on instrument panel will come on. The
OD switch is mounted on shift lever.
Oil Temperature Sensor Signal
Oil temperature sensor provides TCM with ATF temperature
values. TCM uses this information to control shift points for maximum
performance. If transmission oil temperature exceeds standard values,
instrument panel ATF - TEMP light will come on. Sensor is mounted to
cooler line at transmission.
Park/Neutral Position (PNP) Switch Signal
PNP switch delivers an input signal to TCM indicating shift
lever position. Switch is located on side of transmission.
Throttle Position (TP) Sensor Signal
TP sensor delivers closed throttle and variable throttle
position input signals to TCM. TP sensor is located on side of
throttle body.
4WD Low Range Detection Switch
4WD low range detection switch provides information to TCM

when transfer case is in 4WD low-lock range.
Fig. 1: Locating Transmission Control Module (Montero)
Courtesy of Mitsubishi Motor Sales of America.
Fig. 2: Locating Transmission Control Module (Montero Sport)
Courtesy of Mitsubishi Motor Sales of America.
TCM OUTPUT DEVICES

Shift Solenoids No. 1 & No. 2
TCM controls transmission shifting by delivering an output
signal to operate proper solenoid. Solenoids are located on
transmission valve body. See Fig. 3. Solenoids are operated in
accordance with shift lever range. If a solenoid malfunctions, TCM may
select a preselected gear. See Fig. 4.
NOTE: TCM provides a fail-safe system which will place transmission
in preselected gear depending on solenoid failure. In other
gears, fail-safe system will not be activated and
transmission will be placed in a specified gear. See
Fig. 4.
Lock-Up Solenoid
TCM controls torque converter lock-up by delivering an output
signal to lock-up solenoid. Lock-up solenoid is activated when shift
lever is in "D" position and vehicle is at specified speed. Solenoid
is located on transmission valve body. See Fig. 3.
Fig. 3: Locating Lock-Up & Shift Solenoids
Courtesy of Mitsubishi Motor Sales of America.

Fig. 4: Checking Operation Of Shift Solenoids No. 1 & No. 2
Courtesy of Mitsubishi Motor Sales of America.
SELF-DIAGNOSTIC SYSTEM
SYSTEM DIAGNOSIS
NOTE: Before testing transmission, ensure fluid level is correct
and throttle and shift cables are properly adjusted. Ensure
engine starts with shift lever in Park and Neutral to ensure
proper adjustment of park/neutral position switch.
Transmission must first be tested by checking for stored
codes. See RETRIEVING DIAGNOSTIC TROUBLE CODES (DTC).
TCM monitors transmission operation and contains a self-
diagnostic system which stores a DTC if an electronic control system
failure or problem exists. If a problem exists in any of the solenoids
or speed sensors and a DTC is set, TCM delivers a signal to blink the
ATF TEMP light on instrument panel to warn the driver. DTC may be set
if a failure exists and can be retrieved for transmission diagnosis.
RETRIEVING DIAGNOSTIC TROUBLE CODES (DTC)
NOTE: Before retrieving DTC, ensure proper battery voltage exists
for proper self-diagnosis system operation. DO NOT disconnect
battery or ECM connectors before retrieving DTC.
Retrieving Codes Using Scan Tool
Ensure ignition switch is in OFF position. Connect scan tool
to Data Link Connector (DLC). See Fig. 5. Turn ignition switch to ON
position. Check for stored DTC and record code(s). See DIAGNOSTIC
TROUBLE CODE IDENTIFICATION table.

Fig. 5: Retrieving Codes Using Scan Tool
Courtesy of Mitsubishi Motor Sales of America.
Retrieving Codes Using Oil Temperature Warning Light
1) Using jumper wire, ground DLC terminal No. 1. See Fig. 6.
Note number of flashes from oil temperature warning light on
instrument panel. See Fig. 7. If normal system operation exists, oil
temperature warning light will blink 2 times per second. See Fig. 8.
2) If system is operating correctly and no DTC exists, turn
ignition off and remove jumper wire. If DTC exists, oil temperature
warning light will flash once every 2 seconds. The number of flashes
will equal first digit of DTC. After a pause of 2 seconds, second
digit will be displayed. Oil temperature warning light will flash once
every half second for second digit. See Fig. 8.
3) If more than one DTC exists, next DTC will be displayed
after pause of 3 seconds. Smallest DTC number will be first. DTCs will
be repeated.
4) Once DTC is obtained, determine probable cause and
symptom. See DIAGNOSTIC TROUBLE CODE IDENTIFICATION table. To trouble
shoot DTC, see DIAGNOSTIC TESTS. Turn ignition off and remove jumper
wire.
NOTE: Once repairs have been performed, DTCs must be cleared from
TCM memory. See CLEARING DIAGNOSTIC TROUBLE CODES (DTC).

DIAGNOSTIC TROUBLE CODE IDENTIFICATION
DIAGNOSTIC TROUBLE CODE IDENTIFICATION








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DTC ( 1) Probable Cause
11 ........................ Defective TP Sensor Or TP Sensor Circuit
15 ............................. Open Oil Temperature Sensor Circuit
16 ............................ Short Oil Temperature Sensor Circuit
21 ................................... Short Ignition Signal Circuit
22 .................................... Open Ignition Signal Circuit
23 .......................... Open Signal Line (ECT) From ECM To TCM\
24 ......................... Short Signal Line (ECT) From ECM To TCM\
29 ............................. Short Neutral Safety Switch Circuit
30 .............................. Open Neutral Safety Switch Circuit
31 ................................. Open No. 2 Speed Sensor Circuit
32 ................................. Open No. 1 Speed Sensor Circuit
41 ..................................... Open Solenoid No. 1 Circuit
42 .................................... Short Solenoid No. 1 Circuit
43 ..................................... Open Solenoid No. 2 Circuit
44 .................................... Short Solenoid No. 2 Circuit
47 ................................... Open Lock-Up Solenoid Circuit
48 .................................. Short Lock-up Solenoid Circuit
49 .............. ( 2) Torque Converter Clutch Engagement Malfunction
50 ........... ( 2) Torque Converter Clutch Disengagement Malfunction
51 ................................. 1st Gear Ratio Signal Incorrect
52 ................................. 2nd Gear Ratio Signal Incorrect
53 ................................. 3rd Gear Ratio Signal Incorrect
54 ................................. 4th Gear Ratio Signal Incorrect
( 1) - Check listed fault code and component for probable cause. See
appropriate fault code listing under DIAGNOSTIC TESTS. Check
wiring and connections of specified component.
( 2) - Scan tool is required for testing malfunctioning circuit.









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Fig. 6: Identifying Data Link Connector (DLC) Terminals
Courtesy of Mitsubishi Motor Sales of America.

Fig. 7: Locating A/T Temperature Warning Light
Courtesy of Mitsubishi Motor Sales of America.
Fig. 8: Identifying DTC Displays
Courtesy of Mitsubishi Motor Sales of America.
CLEARING DIAGNOSTIC TROUBLE CODES (DTC)

Once repairs have been performed, DTCs must be cleared from
TCM memory. DTCs may be cleared by disconnecting negative battery
cable for 10 seconds or more. Reconnect cable and ensure DTCs have
been cleared. Start engine and warm to normal operating temperature.
Run engine at idle for 10 minutes. DTCs may also be cleared using scan
tool. Refer to manufacturer's instruction manual.
DIAGNOSTIC TESTS
NOTE: For terminal and wire color identification, see WIRING
DIAGRAMS.
DTC 11: THROTTLE POSITION (TP) SENSOR
For diagnosis and testing information, see appropriate SELF-
DIAGNOSTICS article in ENGINE PERFORMANCE section. If TP sensor is
okay, check wiring harness and connectors between TP sensor and TCM.
Repair if necessary. If wiring harness and connectors are okay,
replace TCM.
DTC 15 & 16: OPEN OR SHORT IN OIL TEMPERATURE SENSOR CIRCUIT
1) Test oil temperature for proper operation. See OIL
TEMPERATURE SENSOR under COMPONENT TESTING. If oil temperature sensor
is okay, check wire harness, connectors and ground circuit for poor
connections or damage. Go to next step.
2) If wire harness and connectors are okay, check DTCs again
and verify code No. 15 or No. 16 still exists. If either code still
exists, replace TCM.
DTC 21 & 22: SHORT OR OPEN IN IGNITION SIGNAL CIRCUIT
1) Using an external tachometer, verify vehicles' tachometer
is operating accurately. If tachometer is incorrect, check ignition
coil and ignition power transistor and circuits for malfunction. See
appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE section.
2) If tachometer is okay, check TCM wire harness connector
for poor connection. If wire harness is okay, recheck DTCs. If codes
reappear check wire harness between ignition power transistor and TCM.
If wire harness is okay, replace TCM.
DTC 23 & 24: OPEN OR SHORT IN SIGNAL LINE (ECT) FROM ECM TO
TCM
Check wire harness, connectors and ground circuit for poor
connections or damage. Go to next step. If wire harness and connectors
are okay, check DTCs again and verify code No. 23 or No. 24 still
exists. If either code still exists, replace TCM.
DTC 29 & 30: SHORT OR OPEN IN PARK/NEUTRAL POSITION (PNP)
SWITCH CIRCUIT
1) Check PNP switch for correct operation. See. If PNP switch
is okay, disconnect switch connector and measure voltage between
harness connector terminal No. 1 and ground.
2) If battery voltage does not exist, check wire harness and
connectors. See WIRING DIAGRAMS. If battery voltage exists, check wire
harness and connectors between PNP switch and TCM. If wire harness is
okay, replace TCM.
DTC 31: INPUT SPEED SENSOR