Condition Code Procedure
Air pressure incorrect .. B .................. Require repair
Bead broken ............. A ............ Require replacement.
Bead leaking, caused
by tire ................ A .. Require repair or replacement.
Bead wire/cord exposed .. A ............ Require replacement.
Cord or belt material
exposed ................ A ............ Require replacement.
Cord ply separations .... A ............ Require replacement.
Directional/asymmetrical
tires mounted
incorrectly ............ B ....... Require remounting and/or
repositioning.
Irregular tread wear,
affecting performance .. 2 ........ (1) Suggest replacement.
Load ratings less
than OEM
specifications ......... B ............ Require replacement.
Mixed tread types (all
season, performance, mud
and snow) on same axle . A ............ Require replacement.
Number of punctures
exceeds manufacturer's
limit .................. B ............ Require replacement.
Out of balance .......... B . Require rebalance of tire/wheel
assembly.
Ply separation .......... A ............ Require replacement.
Pull or lead, caused
by tire ................ A .. Require repair or replacement.
Radial and bias or
bias-belted ply tires
on same axle ........... B .. Require repair or replacement.
Radials are on the front
and not on the rear .... B ........... ( 2) Require repair or
replacement.
Run flat damage ......... A ............ Require replacement.
Shoulder cut ............ A ............ Require replacement.
Shoulder puncture ....... A ............ Require replacement.
Shoulder with plug ...... A ............ Require replacement.
Sidewall bulge .......... A ............ Require replacement.
Sidewall cut ............ A ............ Require replacement.
Sidewall indentation .... .. ......... No service required or
suggested.
Sidewall puncture ....... A ............ Require replacement.
Sidewall with plug ...... A ............ Require replacement.
Speed rating
designations
different
on same axle ........... 2 .. Suggest repair or replacement.
Tire and wheel assembly
has excessive run-out .. B ........... ( 3) Require repair or
replacement of appropriate
part.
Tires with more than
1/4" diameter difference
on a four-wheel drive
vehicle ................ B ............ Require replacement.
Tread area puncture larger
in diameter than
manufacturer's
specifications ......... B ............ Require replacement.
Tread missing pieces
Loose ................... B ... Require repair or replacement
of affected component.
Lug nut installed
backward ............... B .. Require repair or replacement.
Lug nut mating type
incorrect .............. B ..... Require replacement of nut.
Lug nut mating surface
dished ................. A ..... Require replacement of nut.
Lug nut rounded ......... A . (2) Require replacement of nut.
Lug nut seized .......... A . ( 2) Require replacement of nut.
Stud incorrect .......... B .... Require replacement of stud.
Threads damaged ......... A ... Require repair or replacement
of component with damaged
threads.
Threads stripped ........ A .......... Require replacement of
component with stripped
threads.
( 1) - Some manufacturers require replacement of all studs on
that wheel if two or more studs or nuts on the same
wheel are broken or missing.
( 2) - Only required if removing wheel.
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WHEELS (RIMS)
WARNING: Mounting a regular tire on a high-pressure compact spare
wheel is not permitted. Attempting to mount a tire of one
diameter on a wheel of a different diameter or flange
type may result in serious injury or death. If the wheel
identification stamp is not legible, or cannot be found,
do not use the wheel until the size and type have been
properly identified. Wheels of different diameter,
offset, or width cannot be mixed on the same axle. Bead
seat tapers cannot be interchanged.
WHEEL (RIM) INSPECTION
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Condition Code Procedure
Bead leaking, caused
by wheel ............... A ........... ( 1) Require repair or
replacement.
Bent hub mounting
surface ................ A ............ Require replacement.
Bent rim, causing
vibration .............. 2 ........ ( 1) Suggest replacement.
Broken .................. A ............ Require replacement.
Cast wheel porous,
causing a leak ......... A .. Require repair or replacement.
Clip-on balance weight is
incorrect type
for rim flange ......... 2 ............ Suggest replacement.
Corrosion, affecting
structural integrity ... A ............ Require replacement.
Corrosion build-up on
wheel mounting
surface ................ A ................. Require repair.
Cracked ................. A ............ Require replacement.
Directional/asymmetrical
wheels mounted
incorrectly ............ B ....... Require remounting and/or
repositioning.
be caused by
faulty alignment ....... A ............. Require alignment.
Part has been changed,
affecting alignment .... A ....... Require alignment check.
Pull, shown to be caused
by faulty alignment .... A ............. Require alignment.
Steering wheel
off-center ............. 2 ............. Suggest alignment.
Tire wear, shown
to be caused by
faulty alignment ....... A ............. Require alignment.
Wander, shown
to be caused by
faulty alignment ....... A ............. Require alignment.
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WHEELS AND TIRES
TIRES
These guidelines do not apply to split rims. Some vehicle
manufacturers restrict replacement of tires to specific brands, types,
or sizes.
WARNING: High pressure temporary compact spare tires should not be
used with any other rims or wheels, nor should standard
tires, snow tires, wheel covers, or trim rings be used
with high pressure compact spare rims or wheels.
Attempting to mount a tire of one diameter on a wheel of
a different diameter or flange type may result in serious
injury or death.
WARNING: Only specially trained persons should dismount or mount
tires. Explosions of tire and wheel assembly can result
from improper mounting, possibly causing serious injury
or death.
WARNING: Consult the vehicle owner's manual or vehicle placard for
correct size, speed rating, designation, and cold
inflation pressure of the original tires. DO NOT exceed
the maximum load or inflation capacity of the tire
specified by the Tire and Rim Association
WARNING: When replacing tires, it is suggested that the
replacement tires match or exceed the OEM speed rating
designation. If tires of different speed rating
designations are mixed on the same vehicle, the tires may
vary in handling characteristics. DO NOT mix different
speed rating designations on the same axle.
WARNING: DO NOT mix radials with non-radial tires on the same
axle, as this may affect vehicle handling and stability.
If radial tires and bias or bias-belted ply tires are
mixed on the same vehicle, the radials must be on the
rear. High-pressure temporary compact spare tires are
exempt from this rule.
WARNING: DO NOT mix size or type (all season, performance, mud and
snow) of tires on the same axle.
TIRE INSPECTION
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Condition Code Procedure
Air pressure incorrect .. B .................. Require repair
Bead broken ............. A ............ Require replacement.
Bead leaking, caused
by tire ................ A .. Require repair or replacement.
Bead wire/cord exposed .. A ............ Require replacement.
Cord or belt material
exposed ................ A ............ Require replacement.
Cord ply separations .... A ............ Require replacement.
Directional/asymmetrical
tires mounted
incorrectly ............ B ....... Require remounting and/or
repositioning.
Irregular tread wear,
affecting performance .. 2 ........ (1) Suggest replacement.
Load ratings less
than OEM
specifications ......... B ............ Require replacement.
Mixed tread types (all
season, performance, mud
and snow) on same axle . A ............ Require replacement.
Number of punctures
exceeds manufacturer's
limit .................. B ............ Require replacement.
Out of balance .......... B . Require rebalance of tire/wheel
assembly.
Ply separation .......... A ............ Require replacement.
Pull or lead, caused
by tire ................ A .. Require repair or replacement.
Radial and bias or
bias-belted ply tires
on same axle ........... B .. Require repair or replacement.
Radials are on the front
and not on the rear .... B ........... ( 2) Require repair or
replacement.
Run flat damage ......... A ............ Require replacement.
Shoulder cut ............ A ............ Require replacement.
Shoulder puncture ....... A ............ Require replacement.
Shoulder with plug ...... A ............ Require replacement.
Sidewall bulge .......... A ............ Require replacement.
Sidewall cut ............ A ............ Require replacement.
Sidewall indentation .... .. ......... No service required or
suggested.
Sidewall puncture ....... A ............ Require replacement.
Sidewall with plug ...... A ............ Require replacement.
Speed rating
designations
different
on same axle ........... 2 .. Suggest repair or replacement.
Tire and wheel assembly
has excessive run-out .. B ........... ( 3) Require repair or
replacement of appropriate
part.
Tires with more than
1/4" diameter difference
on a four-wheel drive
vehicle ................ B ............ Require replacement.
Tread area puncture larger
in diameter than
manufacturer's
specifications ......... B ............ Require replacement.
Tread missing pieces
Loose ................... B ... Require repair or replacement
of affected component.
Lug nut installed
backward ............... B .. Require repair or replacement.
Lug nut mating type
incorrect .............. B ..... Require replacement of nut.
Lug nut mating surface
dished ................. A ..... Require replacement of nut.
Lug nut rounded ......... A . (2) Require replacement of nut.
Lug nut seized .......... A . ( 2) Require replacement of nut.
Stud incorrect .......... B .... Require replacement of stud.
Threads damaged ......... A ... Require repair or replacement
of component with damaged
threads.
Threads stripped ........ A .......... Require replacement of
component with stripped
threads.
( 1) - Some manufacturers require replacement of all studs on
that wheel if two or more studs or nuts on the same
wheel are broken or missing.
( 2) - Only required if removing wheel.
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WHEELS (RIMS)
WARNING: Mounting a regular tire on a high-pressure compact spare
wheel is not permitted. Attempting to mount a tire of one
diameter on a wheel of a different diameter or flange
type may result in serious injury or death. If the wheel
identification stamp is not legible, or cannot be found,
do not use the wheel until the size and type have been
properly identified. Wheels of different diameter,
offset, or width cannot be mixed on the same axle. Bead
seat tapers cannot be interchanged.
WHEEL (RIM) INSPECTION
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Condition Code Procedure
Bead leaking, caused
by wheel ............... A ........... ( 1) Require repair or
replacement.
Bent hub mounting
surface ................ A ............ Require replacement.
Bent rim, causing
vibration .............. 2 ........ ( 1) Suggest replacement.
Broken .................. A ............ Require replacement.
Cast wheel porous,
causing a leak ......... A .. Require repair or replacement.
Clip-on balance weight is
incorrect type
for rim flange ......... 2 ............ Suggest replacement.
Corrosion, affecting
structural integrity ... A ............ Require replacement.
Corrosion build-up on
wheel mounting
surface ................ A ................. Require repair.
Cracked ................. A ............ Require replacement.
Directional/asymmetrical
wheels mounted
incorrectly ............ B ....... Require remounting and/or
repositioning.
axle backlash. If backlash is one inch or less, drive axle is not the
source of clunk noise.
Bearing Whine
Bearing whine is a high-pitched sound similar to a whistle.
It is usually caused by malfunctioning pinion bearings. Pinion
bearings operate at drive shaft speed. Roller wheel bearings may whine
in a similar manner if they run completely dry of lubricant. Bearing
noise will occur at all driving speeds. This distinguishes it from
gear whine, which usually comes and goes as speed changes.
Bearing Rumble
Bearing rumble sounds like marbles being tumbled. It is
usually caused by a malfunctioning wheel bearing. The lower pitch is
because the wheel bearing turns at only about 1/3 of drive shaft
speed.
Chatter On Turns
This is a condition where the entire front or rear of vehicle
vibrates when vehicle is moving. The vibration is plainly felt as well
as heard. Extra differential thrust washers installed during axle
repair can cause a condition of partial lock-up that creates this
chatter.
Axle Shaft Noise
Axle shaft noise is similar to gear noise and pinion bearing
whine. Axle shaft bearing noise will normally distinguish itself from
gear noise by occurring in all driving modes (Drive, cruise, coast and
float), and will persist with transmission in Neutral while vehicle is
moving at problem speed.
If vehicle displays this noise condition, remove suspect
axle shafts, replace wheel seals and install a new set of bearings.
Re-evaluate vehicle for noise before removing any internal components.
Vibration
Vibration is a high-frequency trembling, shaking or grinding
condition (felt or heard) that may be constant or variable in level
and can occur during the total operating speed range of the vehicle.
The types of vibrations that can be felt in the vehicle can
be divided into 3 main groups:
* Vibrations of various unbalanced rotating parts of the
vehicle.
* Resonance vibrations of the body and frame structures caused
by rotating of unbalanced parts.
* Tip-in moans of resonance vibrations from stressed engine or
exhaust system mounts or driveline flexing modes.
DRIVE AXLE - RWD 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. For definitions
of listed noises or sounds, see DRIVE AXLE - NOISE DIAGNOSIS
under POWERTRAIN.
DRIVE AXLE (RWD) TROUBLE SHOOTING
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CONDITION POSSIBLE CAUSE CORRECTION
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
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