battery MITSUBISHI MONTERO 1991 Owners Manual
[x] Cancel search | Manufacturer: MITSUBISHI, Model Year: 1991, Model line: MONTERO, Model: MITSUBISHI MONTERO 1991Pages: 1333, PDF Size: 24.61 MB
Page 1214 of 1333
![MITSUBISHI MONTERO 1991 Owners Manual Incorrect injector pump Check pressure, see
housing pressure FUEL SYSTEMS
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housing pressure FUEL SYSTEMS
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Incorrect injector pump Check pressure, see
housing pressure FUEL SYSTEMS
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Engine Cooling system leaks Check cooling system
Overheating and repair leaks
Belt slipping or damaged Check tension and/or
replace belt
Thermostat stuck closed Remove and replace
thermostat, see
ENGINE COOLING
Head gasket leaking Replace head gasket
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Oil Light on at Low oil pump pressure Check oil pump
Idle operation, see ENGINES
Oil cooler or line Remove restriction
restricted and/or replace cooler
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Engine Won't Injector pump fuel solenoid Remove and check
Shut Off does not return fuel valve solenoid and replace
to OFF position if needed
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VACUUM PUMP DIAGNOSIS
Excessive Noise Loose pump-to-drive Tighten screws
assembly screws
Loose tube on pump assembly Tighten tube
Valves not functioning Replace valves
properly
Oil Leakage Loose end plug Tighten end plug
Bad seal crimp Remove and re-crimp
seal
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FUEL INJECTION TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
BASIC FUEL INJECTION TROUBLE SHOOTING CHART
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CONDITION POSSIBLE CAUSE CORRECTION \
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Engine Won't Cold start valve inoperative Test valve and
Start (Cranks circuit
Normally)
Poor connection;vacuum or Check vacuum and
wiring electrical
connections
Contaminated fuel Test fuel for water
or alcohol
Defective fuel pump relay Test relay and
or circuit wiring
Battery too low Charge and test
battery
Page 1217 of 1333
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OK NOT OK
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* To test secondary ignition * Repair or replace
system, modify a Spark Plug damaged components
by attaching a ground wire as necessary
to the body of the plug and
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widening the gap to 1/4-3/8".
Disconnect spark plug wire
and insert test plug. Ground
plug, crank engine, and
check for spark.
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GOOD SPARK NO SPARK
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* If plug sparks, driveability * Remove coil wire from the
problem is most likely NOT distributor and attach the
in the ignition system. modified spark plug. Ground
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the plug and crank engine
while checking for spark.
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GOOD SPARK NO SPARK
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* If plug has a good spark, * Proceed to the IGNITION
the problem is in the plug PRIMARY TROUBLE SHOOTING
wires, distributor cap, or CHECK CHART below in this
rotor. Replace components article.
as necessary.
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Ignition Primary Trouble Shooting Chart
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START: Visually inspect primary ignition wires for
broken, frayed, split, or cut wires. Also check
for loose, corroded, or disconnected connectors.
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OK NOT OK
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* Check that battery voltage * Repair or replace damaged
is at least 11.5 volts. components as necessary.
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NOT OK OK
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* Replace or recharge the * Check for battery voltage
battery. at the positive terminal of
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the coil.
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OK NOT OK
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* Check air Gap of the Pick-Up * Check resistance of ballast
coil in the distributor. resistor (if used) for the
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correct resistance value.
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OK NOT OK
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* Check Pick-Up coil for * Adjust or replace as
correct resistance value. necessary.
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NOT OK OK
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* Replace Pick-Up coil if * Check control module for
not to specification. good ground connections.
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OK
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* If vehicle fails to run at this point, go to
the appropriate article in the ENGINE
PERFORMANCE section.
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OK NOT OK
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* Check wires from the battery/ * Replace ballast resistor
ignition switch to the coil. if the measured resistance
Also check the coil primary value is not within
and secondary resistance. specification.
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STARTER TROUBLE SHOOTING
NOTE: This is GENERAL information. This article is not intended
to be specific to any unique situation or individual vehicle
configuration. The purpose of this Trouble Shooting
information is to provide a list of common causes to
problem symptoms. For model-specific Trouble Shooting,
refer to SUBJECT, DIAGNOSTIC, or TESTING articles available
in the section(s) you are accessing.
BASIC STARTER TROUBLE SHOOTING CHART
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CONDITION POSSIBLE CAUSE CORRECTION \
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Starter Fails Dead battery or bad Check battery charge
to Operate connections between and all wires and
starter and battery connections to starter
Page 1219 of 1333
Ignition switch faulty Adjust or replace
or misadjusted ignition switch
Open circuit between Check and repair wires
starter switch ignition and connections as
terminal on starter relay necessary
Starter relay or starter See Testing in STARTER
defective article
Open solenoid pull-in See Testing in STARTER
wire article
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Starter Does Not Weak battery or dead Charge or replace
Operate and cell battery as necessary
Headlights Dim
Loose or corroded battery Check that battery
connections connections are clean
and tight
Internal ground in See Testing in STARTER
starter windings article
Grounded starter fields See Testing in STARTERS
Armature rubbing on pole See STARTER article
shoes
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Starter Turns Starter clutch slipping See STARTER article
but Engine
Does Not Rotate
Broken clutch housing See STARTER article
Pinion shaft rusted or See STARTER article
dry
Engine basic timing See Ignition Timing in
incorrect TUNE-UP article
Broken teeth on engine Replace flywheel and
flywheel check for starter pinion
gear damage
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Starter Will Not Faulty overrunning See STARTER article
Crank Engine clutch
Broken clutch housing See STARTER article
Broken flywheel teeth Replace flywheel and
check for starter pinion
gear damage
Armature shaft sheared See STARTER article
or reduction gear teeth
stripped
Weak battery Charge or replace
battery as necessary
Faulty solenoid See On-Vehicle Tests in
STARTER article
Poor grounds Check all ground
Page 1220 of 1333
connections for
tight and clean
connections
Ignition switch faulty Adjust or replace
or misadjusted ignition switch as
necessary
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Starter Cranks Battery weak or Charge or replace
Engine Slowly defective battery as necessary
Engine overheated See ENGINE COOLING
SYSTEM article
Engine oil too heavy Check that proper
viscosity oil
is used
Poor battery-to-starter Check that all
connections between
battery and starter are
clean and tight
Current draw too low or See Bench Tests in
too high STARTER article
Bent armature, loose pole See STARTER article
shoes screws or worn
bearings
Burned solenoid contacts Replace solenoid
Faulty starter Replace starter
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Starter Engages Engine timing too far See Ignition Timing in
Engine Only advanced TUNE-UP article
Momentarily
Overrunning clutch not Replace overrunning
engaging properly clutch. See STARTER
article
Broken starter clutch See STARTER article
Broken teeth on engine Replace flywheel and
flywheel check starter pinion
gear for damage
Weak drive assembly See STARTER article
thrust spring
Weak hold-in coil See Bench Tests in
STARTER article
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Starter Drive Defective point assembly See Testing in STARTER
Will Not Engage article
Poor point assembly ground See Testing in STARTER
article
Defective pull-in coil Replace starter
solenoid
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Starter Relay Dead battery Charge or replace
Page 1221 of 1333
Does Not Close battery as necessary
Faulty wiring Check all wiring and
connections leading to
relay
Neutral safety switch Replace neutral safety
faulty switch
Starter relay faulty Replace starter relay
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Starter Drive Starter motor loose on Tighten starter
Will Not mountings attach bolts
Disengage
Worn drive end bushing See STARTER article
Damaged engine flywheel Replace flywheel and
teeth starter pinion gear for
damage
Drive yolk return spring Replace return spring
broken or missing
Faulty ignition switch Replace ignition switch
Insufficient clearance Replace starter
between winding leads to solenoid
solenoid terminal and main
contact in solenoid
Starter clutch not Replace starter clutch
disengaging
Ignition starter switch Replace ignition switch
contacts sticking
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Starter Relay Faulty solenoid switch, Check all wiring
Operates but switch connections or between relay and
Solenoid Does Not solenoid or replace
relay or solenoid as
necessary
Broken lead or loose Repair wire or wire
soldered connections connections as
necessary
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Solenoid Plunger Weak battery Charge or replace
Vibrates When battery as necessary
Switch is Engaged
Solenoid contacts Clean contacts or
corroded replace solenoid
Faulty wiring Check all wiring
leading to solenoid
Broken connections inside Repair connections or
switch cover replace solenoid
Open hold-in wire Replace solenoid
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Low Current Draw Worn brushes or weak Replace brushes or
brush springs as
necessary
Page 1268 of 1333
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
Page 1270 of 1333
full load. The Kent-Moore J-39021 is such a tool, though there are
others. The Kent-Moore costs around $240 at the time of this writing
and works on many different manufacturer's systems.
The second method is to use a lab scope. Remember, a lab
scope allows you to see the regular operation of a circuit in real
time. If an injector is having an short or intermittent short, the lab
scope will show it.
Checking Available Voltage At the Injector
Verifying a fuel injector has the proper voltage to operate
correctly is good diagnostic technique. Finding an open circuit on the
feed circuit like a broken wire or connector is an accurate check with
a DVOM. Unfortunately, finding an intermittent or excessive resistance
problem with a DVOM is unreliable.
Let's explore this drawback. Remember that a voltage drop due
to excessive resistance will only occur when a circuit is operating?
Since the injector circuit is only operating for a few milliseconds at
a time, a DVOM will only see a potential fault for a few milliseconds.
The remaining 90+% of the time the unloaded injector circuit will show
normal battery voltage.
Since DVOMs update their display roughly two to five times a
second, all measurements in between are averaged. Because a potential
voltage drop is visible for such a small amount of time, it gets
"averaged out", causing you to miss it.
Only a DVOM that has a "min-max" function that checks EVERY
MILLISECOND will catch this fault consistently (if used in that mode).\
The Fluke 87 among others has this capability.
A "min-max" DVOM with a lower frequency of checking (100
millisecond) can miss the fault because it will probably check when
the injector is not on. This is especially true with current
controlled driver circuits. The Fluke 88, among others fall into this
category.
Outside of using a Fluke 87 (or equivalent) in the 1 mS "min-\
max" mode, the only way to catch a voltage drop fault is with a lab
scope. You will be able to see a voltage drop as it happens.
One final note. It is important to be aware that an injector
circuit with a solenoid resistor will always show a voltage drop when
the circuit is energized. This is somewhat obvious and normal; it is a
designed-in voltage drop. What can be unexpected is what we already
covered--a voltage drop disappears when the circuit is unloaded. The
unloaded injector circuit will show normal battery voltage at the
injector. Remember this and do not get confused.
Checking Injector On-Time With Built-In Function
Several DVOMs have a feature that allows them to measure
injector on-time (mS pulse width). While they are accurate and fast to\
hookup, they have three limitations you should be aware of:
* They only work on voltage controlled injector drivers (e.g
"Saturated Switch"), NOT on current controlled injector
drivers (e.g. "Peak & Hold").
* A few unusual conditions can cause inaccurate readings.
* Varying engine speeds can result in inaccurate readings.
Regarding the first limitation, DVOMs need a well-defined
injector pulse in order to determine when the injector turns ON and
OFF. Voltage controlled drivers provide this because of their simple
switch-like operation. They completely close the circuit for the
entire duration of the pulse. This is easy for the DVOM to interpret.
The other type of driver, the current controlled type, start
off well by completely closing the circuit (until the injector pintle
opens), but then they throttle back the voltage/current for the
duration of the pulse. The DVOM understands the beginning of the pulse
Page 1274 of 1333
times by increasing injector pulse width accordingly.
NOTE: Never apply battery voltage directly across a low resistance
injector. This will cause injector damage from solenoid coil
overheating.
Fig. 1: Injector Driver Types - Current and Voltage
CURRENT CONTROLLED CIRCUIT ("PEAK & HOLD")
The current controlled driver inside the computer is more
complex than a voltage controlled driver because as the name implies,
it has to limit current flow in addition to its ON-OFF switching
function. Recall, this driver typically requires injector circuits
with a total leg resistance of less than 12 ohms.
Once the driver is turned ON, it will not limit current flow
until enough time has passed for the injector pintle to open. This
period is preset by the particular manufacturer/system based on the
amount of current flow needed to open their injector. This is
typically between two and six amps. Some manufacturers refer to this
Page 1275 of 1333
as the "peak" time, referring to the fact that current flow is allowed
to "peak" (to open the injector).
Once the injector pintle is open, the amp flow is
considerably reduced for the rest of the pulse duration to protect the
injector from overheating. This is okay because very little amperage
is needed to hold the injector open, typically in the area of one amp
or less. Some manufacturers refer to this as the "hold" time, meaning
that just enough current is allowed through the circuit to "hold" the
already-open injector open.
There are a couple methods of reducing the current. The most
common trims back the available voltage for the circuit, similar to
turning down a light at home with a dimmer.
The other method involves repeatedly cycling the circuit ON-
OFF. It does this so fast that the magnetic field never collapses and
the pintle stays open, but the current is still significantly reduced.
See the right side of Fig. 1 for an illustration.
The advantage to the current controlled driver circuit is the
short time period from when the driver transistor goes ON to when the
injector actually opens. This is a function of the speed with which
current flow reaches its peak due to the low circuit resistance. Also,
the injector closes faster when the driver turns OFF because of the
lower holding current.
NOTE: Never apply battery voltage directly across a low resistance
injector. This will cause injector damage from solenoid coil
overheating.
THE TWO WAYS INJECTOR CIRCUITS ARE WIRED
Like other circuits, injector circuits can be wired in one of
two fundamental directions. The first method is to steadily power the
injectors and have the computer driver switch the ground side of the
circuit. Conversely, the injectors can be steadily grounded while the
driver switches the power side of the circuit.
There is no performance benefit to either method. Voltage
controlled and current controlled drivers have been successfully
implemented both ways.
However, 95% percent of the systems are wired so the driver
controls the ground side of the circuit. Only a handful of systems use
the drivers on the power side of the circuit. Some examples of the
latter are the 1970's Cadillac EFI system, early Jeep 4.0 EFI (Renix
system), and Chrysler 1984-87 TBI.
INTERPRETING INJECTOR WAVEFORMS
INTERPRETING A VOLTAGE CONTROLLED PATTERN
NOTE: Voltage controlled drivers are also known as "Saturated
Switch" drivers. They typically require injector circuits
with a total leg resistance of 12 ohms or more.
NOTE: This example is based on a constant power/switched ground
circuit.
* See Fig. 2 for pattern that the following text describes.
Point "A" is where system voltage is supplied to the
injector. A good hot run voltage is usually 13.5 or more volts. This
point, commonly known as open circuit voltage, is critical because the
injector will not get sufficient current saturation if there is a
voltage shortfall. To obtain a good look at this precise point, you