1991 MITSUBISHI MONTERO fuel

3) Using an ohmmeter, measure resistance between terminals of
solenoid valve. At room temperature, reading should be 36-44 ohms.
Replace solenoid if not to specification.
NOTE: EGR temperature sensor only determines if EGR is operating.
An inoperative sensor will not affect driveability or
exhaust emissions.
EGR Temperature Sensor (California)
1) Remove EGR temperature sensor from EGR valve. Place EGR
temperature sensor in water. While increasing water temperature,
measure resistance between wire terminals.
2) At a temperature of 122
F (50C), resistance should be 60,
000-80,000 ohms. At 212F (100C), resistance should be 11,000-14,000
ohms. Replace EGR temperature sensor if resistance differs
significantly from specifications.
EGR Valve
1) Remove EGR valve. Check valve for sticking, carbon
deposits and damage. Clean valve with solvent if necessary. Apply 19.8
in. Hg to valve diaphragm. If valve does not hold vacuum, replace
valve.
2) Apply specified vacuum to valve diaphragm. See CLOSED IN.
HG in EGR VALVE SPECIFICATIONS table. If valve begins to open below
specification, replace valve.
3) Apply specified vacuum to valve diaphragm. See OPEN IN. HG
in EGR VALVE SPECIFICATIONS table. If valve is not completely open at
or above specification, replace valve.
EGR VALVE SPECIFICATIONS TABLE









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Application Closed Open
In. Hg In. Hg
Montero ....................... 2.4 ........... 6.7
Pickup & Ram-50 ............... 1.2 ........... 9.4









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FUEL EVAPORATION
System Test
1) Disconnect Red-striped purge hose from throttle body, and
connect to hand vacuum pump. Plug nipple on throttle body where purge
hose was removed.
2) With engine coolant temperature at 140
F (60C) or less
and engine idling, apply 14.8 in. Hg. Vacuum should hold. Raise engine
speed to 3000 RPM and again apply 14.8 in. Hg. Vacuum should hold.
3) With engine coolant temperature at 158
F (70C) or more
and engine idling, apply 14.8 in. Hg. Vacuum should hold. Turn engine
off. Start engine and within 3 minutes of starting engine, apply
vacuum. Vacuum should bleed down.
4) With engine running for more than 3 minutes after
starting, raise engine speed to 3000 RPM and apply 14.8 in. Hg. Vacuum
should hold momentarily and then bleed down.
NOTE: In step 4), vacuum should bleed down continuously if vehicle
is at an altitude of 7200 ft. (2200 m) or higher or if
intake air temperature is 122
F (50C) or higher.
Purge Control Solenoid Valve
1) Purge control solenoid valve is located near left shock
tower. Label and disconnect both vacuum hoses from solenoid valve.
Disconnect electrical connector. Connect hand vacuum pump to solenoid

remains on (light may flash) during vehicle operation, cause of
malfunction must be determined by using DIAGNOSTIC FAULT CHARTS (if
testing with voltmeter) or diagnostic CODE CHARTS (if testing with
DRB-II). If a sensor fails, ECU will use a substitute value in its
calculations to continue engine operation. In this condition, vehicle
is functional, but loss of good driveability may result.
INTERMITTENT FAILURES
Intermittent failures may cause CHECK ENGINE light to flicker
or illuminate and go out after the intermittent fault goes away.
However, the corresponding trouble code will be retained in ECU
memory. If related fault does not reoccur within a certain time frame,
related trouble code will be erased from ECU memory. Intermittent
failures may be caused by a sensor, connector or wiring related
problems. See INTERMITTENTS in H - TESTS W/O CODES article.
PRETEST INSPECTION
Before proceeding with diagnosis, the following precautions
must be followed:
* Vehicle must have a fully charged battery and functional
charging system.
* Visually inspect connectors and circuit wiring being worked
on.
* DO NOT disconnect battery or ECU. This will erase any fault
codes stored in ECU.
* DO NOT cause short circuits when performing electrical tests.
This will set additional fault codes, making diagnosis of original
problem more difficult.
* DO NOT use a test light in place of a voltmeter.
* When checking for spark, ensure coil wire is NO more than
1/4" from ground. If coil wire is more than 1/4" from ground,
damage to vehicle electronics and/or ECU may result.
* DO NOT prolong testing of fuel injectors. Engine may
hydrostatically (liquid) lock.
* When a vehicle has multiple fault codes, always repair lowest
number fault code first.
* If DRB-II is being used to diagnose system, always perform
verification test after repairs are made.
ENTERING ON-BOARD DIAGNOSTICS (USING VOLTMETER)
1) Before entering on-board diagnostics, refer to PRETEST
INSPECTION in this article. Turn ignition switch to OFF position.
Locate self-diagnostic connector. See SELF-DIAGNOSTIC TEST CONNECTOR
LOCATION table. Using an analog voltmeter, connect voltmeter positive
lead to self-diagnostic connector terminal No. 1 and negative lead to
terminal No. 12 (ground). See Fig. 6.
2) Turn ignition switch to ON position and disclosure of ECU
memory will begin. If 2 or more systems are non-functional, they are
indicated by order of increasing code number. Indication is made by
12-volt pulses of voltmeter pointer. A constant repetition of short
12-volt pulses indicates system is normal. If system is abnormal,
voltmeter will pulse between zero and 12 volts.
3) Signals will appear on voltmeter as long and short 12-volt
pulses. Long pulses represent tens; short pulses represent ones. For
example 4 long pulses and 3 short pulses indicates Code 43. See

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

Fig. 11: Flow Chart NS-1 (1.5L) (3 of 3)
NS-2: CHECKING FOR FUEL PRESSURE - 1.5L

Fig. 13: Flow Chart NS-2 (1.5L)
NS-3: TESTING FUEL PUMP CIRCUIT - 1.5L

Fig. 55: Flow Chart DR-12 (1.5L) (2 of 2)
DR-13: CODE 42 FUEL PUMP CIRCUIT - 1.5L