1991 MITSUBISHI MONTERO throttle position

input device usage on specific models, see appropriate wiring diagram
in M - WIRING DIAGRAMS.
Air Conditioner Switch
When A/C is turned on, signal is sent to ECU. With engine at
idle, ECU increases idle speed through Idle Speed Control (ISC) motor.\
Airflow Sensor
Incorporated in airflow sensor assembly, airflow sensor is a
Karmen Vortex-type sensor which measures intake airflow rate.
Intake air flows through tunnel in airflow sensor assembly.
Airflow sensor transmits radio frequency signals across direction of
incoming airflow, downstream of vortex. Intake air encounters vortex,
causing turbulence in tunnel.
Turbulence disrupts radio frequency, causing variations in
transmission. Airflow sensor converts frequency transmitted into a
proportionate electrical signal which is sent to ECU.
Airflow Sensor Assembly
Mounted inside air cleaner, incorporates airflow sensor,
atmospheric pressure sensor and intake air temperature sensor.
Atmospheric (Barometric) Pressure Sensor
Incorporated in the airflow sensor assembly, converts
atmospheric pressure to electrical signal which is sent to ECU. ECU
adjusts air/fuel ratio and ignition timing according to altitude.
Coolant Temperature Sensor
Converts coolant temperature to electrical signal for use by
ECU. ECU uses coolant temperature information for controlling fuel
enrichment when engine is cold.
Crankshaft Angle & TDC Sensor Assembly
Assembly is located in distributor on SOHC engines. On DOHC
engines, which use Direct (or Distributorless) Ignition System (DIS)\
,
assembly is separate unit mounted in place of distributor. Assembly
consists of triggering disc (mounted on shaft) and stationary optical
sensing unit. Camshaft drives shaft, triggering optical sensing unit.
ECU determines crank angle and TDC based on signals received from
optical sensing unit.
Detonation Sensor (Turbo Only)
Located in cylinder block, senses engine vibration during
detonation (knock). Sensor converts vibration into electrical signal.
ECU retards ignition timing based on this signal.
Engine Speed (Tach Signal)
ECU uses ignition coil tach signal to determine engine speed.
Idle Position Switch
On all DOHC engines and Sigma 3.0L, idle position switch is
separate switch mounted on throttle body. On all other models, idle
position switch is incorporated in ISC motor or throttle position
sensor, depending on vehicle application. When throttle valve is
closed, switch is activated. When throttle valve is at any other
position, switch is deactivated. This input from idle position switch
is used by ECU for controlling fuel delivery time during deceleration.
Ignition Timing Adjustment Terminal
Used for adjusting base ignition timing. When terminal is
grounded, ECU timing control function is by-passed, allowing base
timing to be adjusted.

Inhibitor Switch (Automatic Transmission Only)
Inhibitor switch senses position of transmission select
lever, indicating engine load due to automatic transmission
engagement. Based on this signal, ECU commands ISC motor to increase
throttle angle, maintaining optimum idle speed.
Intake Air Temperature Sensor
Incorporated in airflow sensor assembly, this resistor-based
sensor measures temperature of incoming air and supplies air density
information to ECU.
Motor Position Sensor (MPS)
Incorporated in ISC motor (or separate unit on some models),
senses ISC motor plunger position and sends electrical signal to ECU.
Oxygen (O2) Sensor
Located in exhaust system, generates an output voltage.
Output voltage varies with oxygen content of exhaust gas stream. ECU
adjusts air/fuel mixture based on signals from oxygen sensor.
Power Steering Oil Pressure Switch
Detects increase in power steering oil pressure. When power
steering oil pressure increases, switch contacts close, signalling
ECU. ECU commands ISC motor, raising idle speed to compensate for drop
in engine RPM due to power steering load.
TDC Sensor
See CRANKSHAFT ANGLE & TDC SENSOR ASSEMBLY.
Throttle Position Sensor (TPS)
A variable resistor mounted on throttle body. ECU uses
voltage signal received from TPS to determine throttle plate angle.
Vehicle Speed Sensor
Located in speedometer in instrument cluster, uses a reed
switch to sense speedometer gear revolutions. ECU uses gear
revolutions to determine vehicle speed.
OUTPUT SIGNALS
NOTE: Vehicles are equipped with different combinations of
computer-controlled components. Not all components listed
below are used on every vehicle. For theory and operation on
each output component, refer to the system indicated in
brackets after component.
CHECK ENGINE Light
See SELF DIAGNOSTIC SYSTEM.
EGR Control Solenoid Valve
See EXHAUST GAS RECIRCULATION (EGR) CONTROL under EMISSION
SYSTEMS.
Fuel Injectors
See FUEL CONTROL under FUEL SYSTEM.
Fuel Pressure Control Solenoid Valve (Turbo Only)
See FUEL DELIVERY under FUEL SYSTEM.
Fuel Pressure Regulator
See FUEL DELIVERY under FUEL SYSTEM.
Fuel Pump Relay (MPI Control Relay)

motor to increase idle speed. To prevent A/C compressor from switching
on before idle speed has increased, ECU momentarily opens A/C relay
circuit.
Idle Speed Control (ISC) Motor
Controls pintle-type air valve (DOHC engines) or throttle
plate angle (SOHC engines) to regulate volume of intake air at idle.
During start mode, ECU controls idle intake air volume
according to coolant temperature input. After starting, with idle
position switch activated (throttle closed), fast idle speed is
controlled by ISC motor and fast idle air control valve (if equipped).\
When idle switch is deactivated (throttle open), ISC motor
moves to a preset position in accordance with coolant temperature
input.
When automatic transmission (if equipped) is shifted from
Neutral to Drive, A/C is turned on or power steering pressure reaches
a preset value, ECU signals ISC motor to increase engine RPM.
Fast Idle Air Control Valve
Some models use a coolant temperature-sensitive fast idle air
control valve, located on throttle body, to admit additional intake
air volume during engine warm-up. Control valve closes as temperature
increases, restricting by-pass airflow rate. At engine warm-up, valve
closes completely.
IGNITION SYSTEMS
DIRECT IGNITION SYSTEM (DIS) - DOHC ENGINES
Ignition system is a 2-coil, distributorless ignition system.
Crankshaft angle and TDC sensor assembly, mounted in place of
distributor, are optically controlled.
Power Transistors & Ignition Coils
Based on crankshaft angle and TDC sensor inputs, ECU controls
timing and directly activates each power transistor to fire coils.
Power transistor "A" controls primary current of ignition coil "A" to
fire spark plugs on cylinders No. 1 and 4 at the same time. Power
transistor "B" controls primary current of ignition coil "B" to fire
spark plugs on cylinders No. 2 and 3 at the same time.
Although each coil fires 2 plugs at the same time, ignition
takes place in only one cylinder since the other cylinder is on its
exhaust stroke when plug fires.
ELECTRONIC IGNITION SYSTEM - SOHC ENGINES
Mitsubishi breakerless electronic ignition system uses a disc
and optical sensing unit to trigger power transistor.
Power Transistor & Ignition Coil
Power transistor is mounted inside distributor with disc and
optical sensing unit. When ignition is on, ignition coil primary
circuit is energized. As distributor shaft rotates, disc rotates,
triggering optical sensing unit. ECU receives signals from optical
sensing unit. Signals are converted and sent to power transistor,
interrupting primary current flow and inducing secondary voltage.
IGNITION TIMING CONTROL SYSTEM
Ignition timing is controlled by ECU. ECU adjusts timing
based upon various conditions, such as engine temperature, altitude
and detonation (turbo vehicles only).

fluid to bring level to lower mark of dipstick if necessary. Recheck
fluid level after transmission is at normal operating temperature.
TRANSFER CASE
Drain plug is located on bottom of transfer case. Change
drain plug gasket whenever fluid is changed. On 3000GT, lubricant
level should be approximately .5" (13 mm) below fill hole on side of
transfer case. On all others models, lubricant level should be to
bottom of fill hole on side of transfer case.
HYDRAULIC CONTROL PRESSURE ADJUSTMENTS
LINE PRESSURE CHECK (EXCEPT MONTERO & PICKUP)
1) Set parking brake. Place shift lever in Neutral position.
Attach engine tachometer. Remove line pressure port plug located above
front transaxle shaft, forward of governor pressure port plug. On
Precis, line pressure port is located below bell housing, at front of
transaxle oil pan. Using appropriate adapter, attach pressure gauge.
2) Start engine, and bring to operating temperature. With
gear selector in Drive position, bring engine speed to 2500 RPM. Pull
throttle control cable (if equipped) wide open at transaxle side.
3) Line pressure should be 98-100 psi (6.9-7.0 kg/cm
) on
Mirage, or 124-127 psi (8.7-8.9 kg/cm) on all others. If line
pressure is not to specification, proceed to LINE PRESSURE ADJUSTMENT.
LINE PRESSURE ADJUSTMENT (EXCEPT MONTERO & PICKUP)
1) Drain transaxle fluid. Remove oil pan. Disconnect throttle
control cable from throttle cam. Remove oil temperature sensor (if
equipped). Disconnect solenoid connector. On some models, it may be
necessary to push solenoid wire harness connector and grommet into
transaxle case.
2) Remove oil filter screen and plate. Noting location and
length of bolts, remove valve body. DO NOT drop internal parts. Adjust
line pressure by turning regulator valve adjusting screw.
3) Turn adjusting screw counterclockwise to increase pressure
or clockwise to decrease pressure. One complete turn of adjusting
screw changes line pressure as follows.
* 3.7 psi (.26 kg/cm
) on Mirage with F3A21 Transaxle
* 5.4 psi (.39 kg/cm) on Precis
* 54 psi (3.8 kg/cm) on all others
4) After adjustment, reverse removal procedure to install.
Refill transaxle.
LINE PRESSURE (MONTERO)
1) Remove plug from line pressure take-off port located
behind transmission shift control lever. Install Hydraulic Pressure
Meter (MD998330) with Adapter (MD998206).
2) Place vehicle on dynamometer. Apply parking brake and
start engine. With brake applied, place transmission in Drive. Note
pressure at idle. Pressure should be 74-85 psi (5.2-6.0 kg/cm
).
3) Raise engine RPM to stall speed (2100-2400 RPM). Note lin\
e
pressure. Pressure should be 156-185 psi (11.0-13.0 kg/cm
).
4) Shift transmission into Reverse with brake applied. At
idle, pressure should be 112-130 psi (7.9-9.1 kg/cm
). Raise engine
RPM to stall speed (2100-2400 RPM). Note line pressure. Pressure
should be 227-285 psi (16.0-20.0 kg/cm
). If readings are not to

specification, use the following trouble shooting guide.
* Hydraulic Pressure High In All Ranges
Check throttle cable adjustment. If adjustment is okay, check
for throttle valve or regulator valve failure.
* Hydraulic Pressure Low In All Ranges
Check throttle cable adjustment. If adjustment is okay, check
for throttle valve, regulator valve, transmission oil pump or
overdrive clutch failure.
* Hydraulic Pressure Low In Drive Position
Check for fluid leaks in Drive hydraulic circuit. Check for
forward clutch or overdrive clutch failure.
* Hydraulic Pressure Low In Reverse Position
Check for fluid leaks in Reverse hydraulic circuit. Check for
transmission No. 3 brake failure, forward clutch failure or
overdrive clutch failure.
LINE PRESSURE (PICKUP)
1) Incorrect throttle pressure setting will cause incorrect
line pressure readings even though line pressure adjustment is
correct. Always inspect and correct throttle pressure adjustment
before adjusting line pressure.
2) Approximate adjustment, measured from valve body to inner
edge of adjusting nut, is 15/16". However, due to manufacturing
tolerances, adjustment can be varied to obtain correct line pressure.
3) Adjusting screw may be turned with an Allen wrench. One
complete turn of adjusting screw changes closed throttle line pressure
approximately 1 2/3 psi. Turn adjusting screw counterclockwise to
increase pressure or clockwise to decrease pressure.
THROTTLE PRESSURE (PICKUP)
1) Throttle pressures cannot be accurately tested. If a
malfunction exists, adjustment should be measured.
2) Insert Gauge Pin (C-3763) between throttle lever cam and
kickdown valve. Push in on tool to compress kickdown valve against its
spring.
3) As force is being exerted to compress spring, turn
throttle lever screw with Allen wrench until head of screw touches
throttle lever tang with gauge pin, and throttle valve bottoms. Ensure
adjustment is made with spring fully compressed and valve bottomed in
valve body.
KICKDOWN BAND
PICKUP
1) Locate kickdown band adjusting screw on left side of
transmission case. Loosen lock nut, and back off nut 5 turns. Ensure
adjusting screw turns freely in transmission case.
2) Using torque wrench, tighten adjusting screw to 72 INCH
lbs. (8 N.m). Back off adjusting screw 2 7/8 turns. Hold adjuster
screw in this position, and tighten lock nut to 30 ft. lbs. (41 N.m).
LOW-REVERSE BAND
PICKUP
1) Raise vehicle, drain transmission, and remove oil pan.
Loosen adjusting screw lock nut, and back off nut 5 turns. Ensure

initially, lock nut and adjustment rod may rotate together.
6) Back off outer section 2-2 3/4 turns. Rotate outer section
to right and inner section to left until inner section is free of lock
nut. Tighten lock nut by hand until it contacts piston. Using torque
wrench, tighten lock nut to 18-23 ft. lbs. (25-32 N.m).
7) Remove adapter and kickdown servo wrench. Install new "O"
ring in groove around switch. Install switch and snap ring.
TRANSMISSION THROTTLE CONTROL
MIRAGE
1) On all other models, ensure throttle lever is in curb idle
position. Engine must be at normal operating temperature.
2) On all models, raise cover "B" of throttle cable upward to
expose nipple. See Fig. 3. Loosen lower cable bracket mounting bolt.
Move lower cable bracket until distance between nipple and top of
cover "A" on throttle cable is .02-.06" (.5-1.5 mm).
3) Tighten lower cable bracket mounting bolt to 108-126 INCH
lbs. (12-14 N.m). With throttle lever in wide open throttle position,
pull cable upward to ensure some cable free play exists.
Fig. 3: Adjusting Throttle Cable (Mirage)
Courtesy of Mitsubishi Motor Sales of America.
CAUTION: On Pickup, always adjust throttle control cable
whenever idle is adjusted.

PICKUP
1) Ensure engine idle is adjusted correctly. Ensure throttle
lever and throttle cable bracket are not bent. Pull lightly on inner
throttle cable.
2) While in closed throttle position, measure gap between
inner cable stopper and outer cable housing. Adjust cable as necessary
to obtain a gap of .031-.059" (.79-1.50 mm). See Fig. 4 (STEP 1).
Fig. 4: Adjusting Throttle Cable (Pickup)
Courtesy of Mitsubishi Motor Sales of America.
3) While holding throttle in wide open position, pull on
inner throttle cable. Adjust bell crank as necessary to obtain a gap
of 1.46-1.50" (37.08-38.10 mm) between inner cable stopper and outer
cable. See Fig. 4 (STEP 2).
4) With throttle fully closed, recheck gap between inner
cable stopper and outer cable housing. Gap should be .031-.059" (.79-
1.50 mm). See Fig. 4 (STEP 3). While holding throttle in wide open
position, pull on inner throttle cable. Check for a gap of 1.30-1.38"
(33.02-35.05 mm).
Montero Ensure throttle lever and throttle cable bracket
are not bent. Ensure distance between inner cable stopper end and dust
cover is 0-.04" (0-1.0 mm). See Fig. 5.
Fig. 5: Adjusting Throttle Cable (Montero)
Courtesy of Mitsubishi Motor Sales of America.
SHIFT LINKAGE

The noid light is an excellent "quick and dirty" tool. It can
usually be hooked to a fuel injector harness fast and the flashing
light is easy to understand. It is a dependable way to identify a no-
pulse situation.
However, a noid light can be very deceptive in two cases:
* If the wrong one is used for the circuit being tested.
Beware: Just because a connector on a noid light fits the
harness does not mean it is the right one.
* If an injector driver is weak or a minor voltage drop is
present.
Use the Right Noid Light
In the following text we will look at what can happen if the
wrong noid light is used, why there are different types of noid lights
(besides differences with connectors), how to identify the types of
noid lights, and how to know the right type to use.
First, let's discuss what can happen if the incorrect type of
noid light is used. You might see:
* A dimly flashing light when it should be normal.
* A normal flashing light when it should be dim.
A noid light will flash dim if used on a lower voltage
circuit than it was designed for. A normally operating circuit would
appear underpowered, which could be misinterpreted as the cause of a
fuel starvation problem.
Here are the two circuit types that could cause this problem:
* Circuits with external injector resistors. Used predominately
on some Asian & European systems, they are used to reduce the
available voltage to an injector in order to limit the
current flow. This lower voltage can cause a dim flash on a
noid light designed for full voltage.
* Circuits with current controlled injector drivers (e.g. "Peak
and Hold"). Basically, this type of driver allows a quick
burst of voltage/current to flow and then throttles it back
significantly for the remainder of the pulse width duration.
If a noid light was designed for the other type of driver
(voltage controlled, e.g. "Saturated"), it will appear dim
because it is expecting full voltage/current to flow for the
entire duration of the pulse width.
Let's move to the other situation where a noid light flashes
normally when it should be dim. This could occur if a more sensitive
noid light is used on a higher voltage/amperage circuit that was
weakened enough to cause problems (but not outright broken). A circuit\
with an actual problem would thus appear normal.
Let's look at why. A noid light does not come close to
consuming as much amperage as an injector solenoid. If there is a
partial driver failure or a minor voltage drop in the injector
circuit, there can be adequate amperage to fully operate the noid
light BUT NOT ENOUGH TO OPERATE THE INJECTOR.
If this is not clear, picture a battery with a lot of
corrosion on the terminals. Say there is enough corrosion that the
starter motor will not operate; it only clicks. Now imagine turning on
the headlights (with the ignition in the RUN position). You find they
light normally and are fully bright. This is the same idea as noid
light: There is a problem, but enough amp flow exists to operate the
headlights ("noid light"), but not the starter motor ("injector").
How do you identify and avoid all these situations? By using
the correct type of noid light. This requires that you understanding