1991 MITSUBISHI MONTERO Service Manual

Fig. 2: Diagnostic Fault Chart (2 of 2)
Courtesy of Mitsubishi Motor Sales of America.
DIAGNOSTIC PROCEDURE (USING DRB-II)
DRB-II PROCEDURE
NOTE: When using diagnostic code charts, DO NOT skip any steps in
chart or incorrect diagnosis may result. Always check related
Technical Service Bulletins (TSB's).
Refer to ENTERING ON-BOARD DIAGNOSTICS (USING DRB-II) to
retrieve fault codes. If fault codes are NOT present and/or DRB-II is
used, proceed to one of the following tests:
* Go to NO START TEST 1 (NS-1) chart if a no-start condition
exists or engine stalls after start-up. Perform indicated
VERIFICATION PROCEDURE chart after repairs. Ensure charts
apply to engine being tested.
* Go to DRIVEABILITY TEST 1 (DR-1) chart if engine runs but has
performance problems. Perform indicated VERIFICATION

PROCEDURE chart after repairs. Ensure charts apply to engine
being tested.
DRB-II KEY FUNCTIONS
* YES or Down Arrow & NO or Up Arrow
Keys will move lines on screen up or down allowing you to
choose an item or scroll through all selections
available.
* F1 & F2 Keys
Keys are used to scroll through sensor displays.
* ATM Key
Key will return you to previous screen.
* ENTER Key
Allows you to select a test or display. The flashing
arrow must be on the display you wish to select. Pressing
ENTER in the sensor state will cause display to change
from a 3-line display to a 1-line display.
* F3 Key
Key is used to display a help screen. This key may be
used at any time.
* Number Keys
Keys are used for choosing a display or test by the
number for the test or display.
* READ/HOLD Key
Key is used to freeze any sensor display.
* MODE & ATM Key
Pressing MODE and ATM key at the same time will cause
DRB-II to reset to copyright screen.
ENTERING ON-BOARD DIAGNOSTICS (USING DRB-II)
* PLEASE READ THIS FIRST *
1) Before entering on-board diagnostics, refer to PRETEST
INSPECTION in this article. Turn ignition off. Locate self-diagnostic
connector. See SELF-DIAGNOSTIC TEST CONNECTOR LOCATION table in this
article. Using appropriate Mitsubishi cartridge and adapter, connect
DRB-II to diagnostic connector.
2) Ensure all accessories are off. Turn ignition on. All
character positions will illuminate and copyright information will
appear on screen for a few seconds.
3) If DRB-II screen displays an error message, refer to DRB-
II ERROR SCREENS in this article. The DRB-II will offer 4 menus:
VEHICLES TESTED, HOW TO USE, CONFIGURE and SELECT VEHICLE.
VEHICLES TESTED
Press "1" key or ENTER key when VEHICLES TESTED appears on
DRB-II. DRB-II shows models covered by cartridge. Screen will display
for 5 seconds and return to DRB-II menu. To return to DRB-II menu
sooner, press ATM key.
HOW TO USE
Press "2" key or press down arrow to display HOW TO USE
option and press ENTER. Press and hold F3 key. DRB-II displays
instructions for cartridge usage. To return to DRB-II menu, press ATM
key.
CONFIGURE

Press "3" key or press down arrow to display CONFIGURE option
and press ENTER. Configure allows user to customize DRB-II display.
For example, If metric system is more useful, select METRIC from the
menu. All selections in CONFIGURE option remain active until user
changes selection.
SELECT VEHICLE
1) This allows the user to enter information about vehicle
being tested. Usually, this option has more than one display screen.
Use ENTER key to enter vehicle information.
2) When all information about vehicle is entered, DRB-II will
display an information summary the technician has entered. DRB-II will
show an additional option marked CONFIRM. If information is correct,
press CONFIRM. DRB-II will display MAIN MENU.
MAIN MENU
The MAIN MENU represents all diagnostic functions available.
Functions are SYSTEM TESTS, READ FAULTS, STATE DISPLAYS, ACTUATOR
TESTS and ADJUSTMENTS. SYSTEM TESTS is NOT available.
READ FAULTS
This allows technician to read fault codes stored in ECU
memory.
STATE DISPLAYS
1) This allows technician to view conditions at signal level.
The 2 types of signals are analog and digital. Analog signals are
monitored at pins corresponding to vehicle harness splices (e.g. fuel
pump relay).
2) Digital signals correspond to data transmitted by the
system controllers. Both signals are displayed in common units (e.g.
temperature). Use up and down arrow keys on DRB-II to scroll through
displays available.
3) The following ENGINE state displays are available on DRB-
II:
* Module Information - This mode allows technician to read ECU
part number and application.
* Engine Sensors - This mode allows technician to look at
various engine sensors during engine operation.
* Inputs/Outputs - This mode allows technician to read input
and output states of various switches and sensors.
* Custom Display - This screen allows technician to set up
his/her own custom display. Two custom display screens can be
programmed into DRB-II.
* Minimum/Current/Maximum - The MIN/CURRENT/MAX display shows a
history of conditions for a specific sensor. When this option
is selected, maximum, current (static) and minimum values can\
be displayed for a specific sensor. To reset sensors to a
zero value, simply press ENTER key. This display may be used
to isolate intermittent faults. The MIN/CURRENT/MAX display
allows technician to observe operation of 6 different sensor
values. Information is displayed as a 3-digit number. The
first value displayed is the minimum reading, the second
number is the current reading and third valve is the maximum
reading. Typically sensors range between 2-252. Values less
than 2 or greater than 252 will usually indicate that a

sensor is shorted or disconnected. Watch minimum and maximum
values to help diagnose intermittent problems.
* Monitors - This screen shows technician sensors and system
controllers which affect fuel control, spark advance, RPM and
A/C relay. There are 4 different screens available. As an
example, screen No. 1 will show: airflow sensor, O2 sensor,
battery and fuel injector. All of these inputs affect fuel
control.
Actuator Tests
This mode allows technician to actuate injectors, fuel pump,
purge control, EGR solenoid, fuel pressure solenoid and wastegate.
Adjustments
This option provides a means for erasing fault code
information stored in ECU. Follow DRB-II instructions to accomplish
this task.
DRB-II ERROR SCREENS
ERROR SCREENS
SYSTEM FAULT ROM CHECK SUM XXXX Message
Cartridge or DRB-II failure.
SYSTEM FAULT KEYBOARD FAILURE Message
Restart DRB-II. Ensure DRB-II keys are not pressed during
power up. Another possibility is DRB-II failure.
SYSTEM FAULT ROM FAILURE XXXX
DRB-II failure.
SYSTEM FAULT EEPROM FAILURE
DRB-II failure.
SYSTEM FAILURE, COMMUNICATION FAILURE, REFER TO DIAGNOSTIC
PROCEDURES Message
Perform diagnostic connector test. See DRIVEABILITY TEST No.
8 (DR-8). Failure of Mitsubishi Motor Corporation (MMC) adapter is
another possibility.
SYSTEM FAILURE NO RESPONSE FROM ADAPTER or SYSTEM FAILURE
ADAPTER REQUIRED TO DIAGNOSE WITH THIS CARTRIDGE Message
Ensure you are using a correct Mitsubishi Motor Corporation
cartridge. Failure of MMC adapter is another possibility.
Fig. 3: 10-Way ECU Connector
Courtesy of Chrysler Motors.

Fig. 4: 18-Way ECU Connector
Courtesy of Chrysler Motors.
Fig. 5: 24-Way ECU Connector
Courtesy of Chrysler Motors.
Fig. 6: Self-Diagnostic Connector Terminal Identification
Courtesy of Mitsubishi Motor Sales of America.
FAULT CODES
FAULT CODES TABLE








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Fault Code System Fault Description
11 .................... Open or short in O2 sensor circuit
12 ............... Open or short in airflow sensor circuit
13 ...... Open or short in intake air temp. sensor circuit
14 .......................... Open or short in TPS circuit
15 (1) .... Open or short in motor position sensor circuit
21 ......... Open or short in coolant temp. sensor circuit
22 ........ No voltage change in crank angle sensor signal
23 ............... No voltage change in TDC sensor circuit
24 ( 2) .. No voltage change in vehicle speed sensor signal
25 ........... Open or short in barometric pressure sensor
31 ( 3) ........ Open or short in detonation sensor circuit
41 ..................... Open or short in injector circuit
42 .............. Open or short in fuel pump drive circuit
43 ( 4) ......... Open or short in EGR temp. sensor circuit

44 (5) ..... Open or short in either ignition coil circuit
( 1) - Except Montero & Sigma.
( 2) - Will not turn on CHECK ENGINE light.
( 3) - 2.0L turbo only.
( 4) - California only. Except Sigma.
( 5) - Chrysler Motors models only.









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CLEARING CODES
Using DRB-II, from main menu select ADJUSTMENTS. Enter ERASE
FAULTS. Follow DRB-II instructions to accomplish this task. If DRB-II
is not available, fault codes may be cleared by disconnecting negative
battery cable for at least 10 seconds, allowing ECU to clear fault
codes.
TEST CHARTS
* PLEASE READ THIS FIRST *
NOTE: The following charts are supplied for Chrysler Motors
vehicles.
NS-1: TESTING IGNITION CIRCUIT - 1.5L
Fig. 7: Circuit Diagram NS-1 (1.5L) (1 of 2)
Fig. 8: Circuit Diagram NS-1 (1.5L) (2 of 2)

Fig. 9: Flow Chart NS-1 (1.5L) (1 of 3)

Fig. 10: Flow Chart NS-1 (1.5L) (2 of 3)