will need to shift your Lab Scope to five volts per division.
You will find that some systems have slight voltage
fluctuations here. This can occur if the injector feed wire is also
used to power up other cycling components, like the ignition coil(s).
Slight voltage fluctuations are normal and are no reason for concern.
Major voltage fluctuations are a different story, however. Major
voltage shifts on the injector feed line will create injector
performance problems. Look for excessive resistance problems in the
feed circuit if you see big shifts and repair as necessary.
Note that circuits with external injector resistors will not
be any different because the resistor does not affect open circuit
voltage.
Point "B" is where the driver completes the circuit to
ground. This point of the waveform should be a clean square point
straight down with no rounded edges. It is during this period that
current saturation of the injector windings is taking place and the
driver is heavily stressed. Weak drivers will distort this vertical
line.
Point "C" represents the voltage drop across the injector
windings. Point "C" should come very close to the ground reference
point, but not quite touch. This is because the driver has a small
amount of inherent resistance. Any significant offset from ground is
an indication of a resistance problem on the ground circuit that needs
repaired. You might miss this fault if you do not use the negative
battery post for your Lab Scope hook-up, so it is HIGHLY recommended
that you use the battery as your hook-up.
The points between "B" and "D" represent the time in
milliseconds that the injector is being energized or held open. This
line at Point "C" should remain flat. Any distortion or upward bend
indicates a ground problem, short problem, or a weak driver. Alert
readers will catch that this is exactly opposite of the current
controlled type drivers (explained in the next section), because they
bend upwards at this point.
How come the difference? Because of the total circuit
resistance. Voltage controlled driver circuits have a high resistance
of 12+ ohms that slows the building of the magnetic field in the
injector. Hence, no counter voltage is built up and the line remains
flat.
On the other hand, the current controlled driver circuit has
low resistance which allows for a rapid magnetic field build-up. This
causes a slight inductive rise (created by the effects of counter
voltage) and hence, the upward bend. You should not see that here with
voltage controlled circuits.
Point "D" represents the electrical condition of the injector
windings. The height of this voltage spike (inductive kick) is
proportional to the number of windings and the current flow through
them. The more current flow and greater number of windings, the more
potential for a greater inductive kick. The opposite is also true. The
less current flow or fewer windings means less inductive kick.
Typically you should see a minimum 35 volts at the top of Point "D".
If you do see approximately 35 volts, it is because a zener
diode is used with the driver to clamp the voltage. Make sure the
beginning top of the spike is squared off, indicating the zener dumped
the remainder of the spike. If it is not squared, that indicates the
spike is not strong enough to make the zener fully dump, meaning the
injector has a weak winding.
If a zener diode is not used in the computer, the spike from
a good injector will be 60 or more volts.
Point "E" brings us to a very interesting section. As you
can see, the voltage dissipates back to supply value after the peak of
the inductive kick. Notice the slight hump? This is actually the
mechanical injector pintle closing. Recall that moving an iron core
through a magnetic field will create a voltage surge. The pintle is
drivers. They typically require injector circuits
with a total leg resistance with less than 12 ohm.
NOTE: This example is based on a constant power/switched ground
circuit.
* See Fig. 3 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
will need to shift your Lab Scope to five volts per division.
You will find that some systems have slight voltage
fluctuations here. This could occur if the injector feed wire is also
used to power up other cycling components, like the ignition coil(s).
Slight voltage fluctuations are normal and are no reason for concern.
Major voltage fluctuations are a different story, however. Major
voltage shifts on the injector feed line will create injector
performance problems. Look for excessive resistance problems in the
feed circuit if you see big shifts and repair as necessary.
Point "B" is where the driver completes the circuit to
ground. This point of the waveform should be a clean square point
straight down with no rounded edges. It is during this period that
current saturation of the injector windings is taking place and the
driver is heavily stressed. Weak drivers will distort this vertical
line.
Point "C" represents the voltage drop across the injector
windings. Point "C" should come very close to the ground reference
point, but not quite touch. This is because the driver has a small
amount of inherent resistance. Any significant offset from ground is
an indication of a resistance problem on the ground circuit that needs
repaired. You might miss this fault if you do not use the negative
battery post for your Lab Scope hook-up, so it is HIGHLY recommended
that you use the battery as your hook-up.
Right after Point "C", something interesting happens. Notice
the trace starts a normal upward bend. This slight inductive rise is
created by the effects of counter voltage and is normal. This is
because the low circuit resistance allowed a fast build-up of the
magnetic field, which in turn created the counter voltage.
Point "D" is the start of the current limiting, also known as
the "Hold" time. Before this point, the driver had allowed the current
to free-flow ("Peak") just to get the injector pintle open. By the
time point "D" occurs, the injector pintle has already opened and the
computer has just significantly throttled the current back. It does
this by only allowing a few volts through to maintain the minimum
current required to keep the pintle open.
The height of the voltage spike seen at the top of Point "D"
represents the electrical condition of the injector windings. The
height of this voltage spike (inductive kick) is proportional to the
number of windings and the current flow through them. The more current
flow and greater number of windings, the more potential for a greater
inductive kick. The opposite is also true. The less current flow or
fewer windings means less inductive kick. Typically you should see a
minimum 35 volts.
If you see approximately 35 volts, it is because a zener
diode is used with the driver to clamp the voltage. Make sure the
beginning top of the spike is squared off, indicating the zener dumped
the remainder of the spike. If it is not squared, that indicates the
spike is not strong enough to make the zener fully dump, meaning there
is a problem with a weak injector winding.
If a zener diode is not used in the computer, the spike from
WHEEL A LIG NM EN T S PEC IF IC ATIO NS
1999 D odge P ic ku p R 1500
1998-99 WHEEL ALIGNMENT
CHRY - Specifications & Procedures - Trucks & FWD Vans
Caravan, Dakota, Durango, Ram Pickup, Ram Van/Wagon,
Town & Country, Voyager
NOTE: Prior to performing wheel alignment, perform visual and
mechanical inspection of wheels, tires and suspension
components. See PRE-ALIGNMENT INSTRUCTIONS in WHEEL ALIGNMENT
THEORY & OPERATION article in GENERAL INFORMATION.
RIDING HEIGHT ADJUSTMENT
CHECKING PROCEDURE
NOTE: Information on vehicles not listed was not available from
manufacturer.
1999 Caravan, Town & Country, & Voyager
Before adjusting alignment, check riding height. Measure
height from inboard edge of fenderwell directly above center of wheel,
unless specified otherwise. Riding height must be checked with vehicle
on level floor, correct size tires properly inflated and fuel tank
full. Bounce vehicle several times and allow suspension to settle.
Visually inspect vehicle for signs of abnormal height from
front-to-rear and side-to-side. Check passenger and luggage
compartments for extra-heavy items and remove if present. Riding
height between left side and right side of vehicle should vary less
than 0.5 (12.7 mm). Information on riding height between front and
rear is not available from manufacturer. See RIDING HEIGHT
SPECIFICATIONS (1999 CARAVAN, TOWN & COUNTRY, & VOYAGER) table. If
riding height is not within specification, check, repair or replace
suspension components.
Dakota & Durango (4WD)
1) Measure and record distance between floor surface and
center of lower suspension arm rear mounting bolt head. Measure and
record distance between floor surface and center of front wheel. See
Fig. 1 . Subtract first measurement from second measurement. On Dakota,
difference between both measurements should be 1.725-1.975" (43.82-50.
16 mm). On Durango, difference between both measurements should be 2.
78-3.02" (70.6-76.7 mm).
2) If necessary, adjust height differential to specification.
Adjust each front suspension arm by rotating torsion bar anchor
adjustment bolt clockwise to raise vehicle and counterclockwise to
lower vehicle. Always raise vehicle to correct height. If vehicle
height is greater than maximum specification, lower height to less
than specification, then back up to specification. After each
adjustment, jounce vehicle before measuring height to determine
effects of adjustment.
Fig. 1: Measuring Riding Height (Dakota & Durango 4WD)
Courtesy of Chrysler Corp.
JACKING & HOISTING
FLOOR JACK
CAUTION: DO NOT place jack under any part of vehicle underbody. DO NOT
attempt to raise one entire side of vehicle by placing a jack
midway between front and rear wheels, as permanent body
damage could occur. DO NOT place jack under an axle tube,
aluminum differential, steering linkage, engine or
transmission oil pan, fuel tank or front suspension arm.
Caravan, Town & Country, & Voyager
To raise front end, place floor jack under front crossmember
forward flange, inboard of lower control arm pivot. To raise rear end,
place floor jack under rear axle, next to leaf spring mount. See
Fig. 2 .
crossmember, inboard of lower control arm pivot. See Fig. 5. To raise
rear end, place floor jack under rear axle, next to leaf spring "U"
bolt mount.
Fig. 5: Identifying Hoisting & Jacking Locations (Ram Van/Wagon)
Courtesy of Chrysler Corp.
RIDING HEIGHT SPECIFICATIONS (1999 CARAVAN, TOWN & COUNTRY, & VOYAGER)\
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vehicle is at normal riding height.
* Steering wheel must be centered with wheels in straight ahead
position. If required, shorten one tie rod adjusting sleeve
and lengthen opposite sleeve (equal amount of turns). See
Fig. 2.
* Wheel bearings should have the correct preload and lug nuts
must be tightened to manufacturer's specifications. Adjust
camber, caster and toe-in using this sequence. Follow
instructions of the alignment equipment manufacturer.
CAUTION: Do not attempt to correct alignment by straightening parts.
Damaged parts must be replaced.
Fig. 2: Adjusting Tie Rod Sleeves (Top View)
CAMBER
1) Camber is the tilting of the wheel, outward at either top
or bottom, as viewed from front of vehicle. See Fig. 3.
2) When wheels tilts outward at the top (from centerline of
vehicle), camber is positive. When wheels tilt inward at top, camber
is negative. Amount of tilt is measured in degrees from vertical.
subtracted by the width measured at the front of the tires at about
spindle height. A positive figure would indicate toe-in and a negative
figure would indicate toe-out. If the distance between the front and
rear of the tires is the same, toe measurement would be zero. To
adjust:
1) Measure toe-in with front wheels in straight ahead
position and steering wheel centered. To adjust toe-in, loosen clamps
and turn adjusting sleeve or adjustable end on right and left tie
rods. See Figs. 2 and 5.
2) Turn equally and in opposite directions to maintain
steering wheel in centered position. Face of tie rod end must be
parallel with machined surface of steering rod end to prevent binding.
3) When tightening clamps, make certain that clamp bolts are
positioned so there will be no interference with other parts
throughout the entire travel of linkage.
Fig. 5: Wheel Toe-In (Dimension A Less Dimension B)
TOE-OUT ON TURNS
1) Toe-out on turns (turning radius) is a check for bent or
damaged parts, and not a service adjustment. With caster, camber, and
toe-in properly adjusted, check toe-out with weight of vehicle on
wheels.
2) Use a full floating turntable under each wheel, repeating
test with each wheel positioned for right and left turns. Incorrect
toe-out generally indicates a bent steering arm. Replace arm, if
necessary, and recheck wheel alignment.