1999 DODGE RAM Ignition system


WAVEFO RM S - IN JE C TO R P A TTE R N T U TO RIA L

1999 D odge P ic ku p R 1500
GENERAL INFORMATION
Waveforms - Injector Pattern Tutorial
* PLEASE READ THIS FIRST *
NOTE: This article is intended for general information purposes
only. This information may not apply to all makes and models.
PURPOSE OF THIS ARTICLE
Learning how to interpret injector drive patterns from a Lab
Scope can be like learning ignition patterns all over again. This
article exists to ease you into becoming a skilled injector pattern
interpreter.
You will learn:
* How a DVOM and noid light fall short of a lab scope.
* The two types of injector driver circuits, voltage controlled
& current controlled.
* The two ways injector circuits can be wired, constant
ground/switched power & constant power/switched ground.
* The two different pattern types you can use to diagnose with,
voltage & current.
* All the valuable details injector patterns can reveal.
SCOPE OF THIS ARTICLE
This is NOT a manufacturer specific article. All different
types of systems are covered here, regardless of the specific
year/make/model/engine.
The reason for such broad coverage is because there are only
a few basic ways to operate a solenoid-type injector. By understanding
the fundamental principles, you will understand all the major points
of injector patterns you encounter. Of course there are minor
differences in each specific system, but that is where a waveform
library helps out.
If this is confusing, consider a secondary ignition pattern.
Even though there are many different implementations, each still has
a primary voltage turn-on, firing line, spark line, etc.
If specific waveforms are available in On Demand for the
engine and vehicle you are working on, you will find them in the
Engine Performance section under the Engine Performance category.
IS A LAB SCOPE NECESSARY?
INTRODUCTION
You probably have several tools at your disposal to diagnose
injector circuits. But you might have questioned "Is a lab scope
necessary to do a thorough job, or will a set of noid lights and a
multifunction DVOM do just as well?"
In the following text, we are going to look at what noid
lights and DVOMs do best, do not do very well, and when they can
mislead you. As you might suspect, the lab scope, with its ability to
look inside an active circuit, comes to the rescue by answering for
the deficiencies of these other tools.
OVERVIEW OF NOID LIGHT

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

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

POWER WINDOW MOTOR
NOTE: On Dakota, window motor and regulator are serviced as an
assembly.
1) Remove door trim panel. See DOOR TRIM PANEL under REMOVAL
& INSTALLATION. Disconnect window motor connector. Using jumper wires,
apply battery voltage to window motor terminals. Motor should operate,
unless window is already at maximum travel.
2) Reverse jumper wires. Window should move in opposite
direction. If window does not move in either direction, replace window
motor.
3) If motor operates in one direction only, replace motor.
See POWER WINDOW MOTOR under REMOVAL & INSTALLATION. If motor grunts
and does not move, disconnect window glass from regulator plate. Check
window glass, tracks and regulator for sticking, binding or improper
adjustment. Repair as necessary and recheck system operation.
POWER WINDOW SWITCH
1) Remove window switch from door trim panel. See POWER
WINDOW SWITCH under REMOVAL & INSTALLATION. Using an ohmmeter, check
switch continuity. See appropriate WINDOW SWITCH CONTINUITY table.
Replace power window switch as necessary. See appropriate
illustration. See Figs. 1 - 6.
2) Vehicles equipped with Auto Down feature have electronic
components in switch to actuate Auto Down. To test, check switch
continuity, reconnect switch, turn ignition on and test feature. If
Auto Down does not work, replace switch.
Fig. 1: Identifying Driver's Window Switch Terminals (Caravan,
Durango, Town & Country, & Voyager)
Courtesy of Chrysler Corp.
Fig. 2: Identifying Passenger's Window Switch & Vent Switch
Terminals (Caravan, Town & Country, & Voyager)

DRIVER'S WINDOW SWITCH CONTINUITY (RAM VAN & RAM WAGON)








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Switch Position Continuity Between Terminals
Off ..................................... 1 & 2; 2 & 3; 3 & 4; 4 & 6
Up
Left .................................. 1 & 5; 2 & 3; 3 & 4; 4 & 6
Right ................................. 1 & 2; 2 & 4; 3 & 5; 4 & 6
Down
Left .................................. 1 & 2; 2 & 3; 3 & 4; 5 & 6
Right ................................. 1 & 2; 2 & 3; 3 & 6; 4 & 5









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PASSENGER'S WINDOW SWITCH CONTINUITY (CARAVAN, TOWN & COUNTRY, &
VOYAGER)









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Switch Position Continuity Between Terminals
Off ................................................... 2 & 5; 3 & 8
Up ........................................................... 4 & 8
Down ......................................................... 4 & 5









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PASSENGER'S WINDOW SWITCH CONTINUITY (DAKOTA & RAM PICKUP)








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Switch Position Continuity Between Terminals
Off ................................................... 1 & 4; 2 & 3
Up ................................................... 2 & 3; 4 & 11
Down ................................................. 1 & 4; 3 & 11
Light ....................................................... 8 & 11









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PASSENGER'S WINDOW SWITCH CONTINUITY (DURANGO)








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Switch Position Continuity Between Terminals
Off ................................................... 2 & 5; 3 & 6
Up .................................................... 2 & 5; 3 & 4
Down .................................................. 3 & 6; 4 & 5









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PASSENGER'S WINDOW SWITCH CONTINUITY (RAM VAN & RAM WAGON)








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Switch Position Continuity Between Terminals
Off ................................................... 1 & 4; 2 & 3
Up .................................................... 1 & 4; 3 & 5
Down .................................................. 2 & 3; 1 & 5









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SYSTEM TESTS
ALL WINDOWS INOPERATIVE
Caravan, Town & Country, & Voyager
1) Check Positive Temperature Coefficient (PTC) for power
window system. See TROUBLE SHOOTING. Replace PTC as necessary. If PTC
is okay, go to next step.
2) Remove driver's power window switch. See POWER WINDOW
SWITCH under REMOVAL & INSTALLATION. Turn ignition on. Using test
light, connect ground lead to harness connector terminal No. 13 (Black

Wire). Check for voltage by touching test light probe to harness
connector terminals No. 9 (Tan/Dark Green Wire) and No. 11 (Tan Wire)\
.
3) If test light illuminates, ground circuit and circuit
between battery and switch are okay. If test light does not
illuminate, check power and ground circuits. See WIRING DIAGRAMS.
Dakota & Ram Pickup
1) Check circuit breaker for power window system. See TROUBLE
SHOOTING. Replace circuit breaker as necessary. If circuit breaker is
okay, go to next step.
2) Remove driver's front power window switch. See POWER
WINDOW SWITCH under REMOVAL & INSTALLATION. Check for continuity
between ground and terminal No. 3 at driver power window switch wiring
harness connector. See WIRING DIAGRAMS. If continuity exists, go to
next step. If continuity does not exist, repair open in Black/Light
Green wire (Ram Pickup) or Black wire (Dakota) between driver power
window switch connector and ground.
3) Turn ignition on. Measure voltage between ground and
terminal No. 5 (Tan wire) at driver's power window switch wiring
harness connector. If battery voltage is present, check driver power
window switch. See POWER WINDOW SWITCH under COMPONENT TESTS. If
battery voltage is not present, repair open Tan wire between driver
power window switch connector and ignition switch. See WIRING
DIAGRAMS.
Durango
1) Check circuit breaker for power window system. See TROUBLE
SHOOTING. Replace circuit breaker as necessary. If circuit breaker is
okay, go to next step.
2) Disconnect negative battery cable. Remove driver's front
power window switch. See POWER WINDOW SWITCH under REMOVAL &
INSTALLATION.
3) Check for continuity between ground and terminal No. 5
(Black wire) at driver's power window switch wiring harness connector.\
See WIRING DIAGRAMS. If continuity exists, go to next step. If
continuity does not exist, repair open in Black wire between driver's
power window switch connector and ground.
4) Reconnect negative battery cable. Turn ignition on.
Measure voltage between ground and terminal No. 4 (Tan wire) at
driver's power window switch wiring harness connector. If battery
voltage is present, check driver's power window switch. See POWER
WINDOW SWITCH under COMPONENT TESTS. If battery voltage is not
present, repair open Tan wire between driver power window switch
connector and ignition switch. See WIRING DIAGRAMS.
Ram Van & Ram Wagon
1) Check circuit breaker for power window system. See TROUBLE
SHOOTING. Replace circuit breaker as necessary. If circuit breaker is
okay, go to next step.
2) Remove driver's front power window switch. See POWER
WINDOW SWITCH under REMOVAL & INSTALLATION. Check for continuity
between ground and driver power window switch wiring harness connector
terminal No. 2 (Black wire). If continuity exists, go to next step. If\
continuity does not exist, repair open in Black wire between driver
power window switch connector and ground.
3) Check for battery voltage at driver's power window switch
harness connector terminal No. 5. If battery voltage exists, check
window switch. See POWER WINDOW SWITCH under COMPONENT TESTS. If
battery voltage does not exist, repair open Tan wire.
ONE WINDOW INOPERATIVE
NOTE: Window glass must be free to slide up and down for power

window motor to function properly. If glass is not free to
move up and down, motor will overload and trip the circuit
breaker.
Dakota & Ram Pickup
1) Place window glass halfway between up and down positions.
Verify glass can be moved slightly from side to side, front to rear,
and up and down. If glass does not move freely, check window glass,
tracks and regulator for sticking, binding or improper adjustment.
Repair as necessary and recheck system operation. If glass moves
freely, go to next step.
2) Disconnect negative battery cable. Remove power window
switch from door with inoperative window. Disconnect power window
switch connector. Connect negative battery cable. Turn ignition on.
Check for battery voltage at power window switch harness connector
terminal No. 5 (driver's window) or terminal No. 11 (passenger's
window). If battery voltage does not exist, repair open Tan wire
between junction block and power window switch. If battery voltage
exists, go to next step (inoperative passenger's window) or go step 4)\
(inoperative driver's window).
3) Disconnect negative battery cable. Check for continuity
between ground and passenger window switch harness connector terminals
No. 1 (Brown/White wire) and 2 (Violet/White wire). If continuity
exists, go to next step. If continuity does not exist, repair open
circuit in wiring harness between window switches.
4) Check power window switch. See POWER WINDOW SWITCH under
COMPONENT TESTS. Replace faulty power window switch as necessary. If
switch is okay, go to next step.
5) Check for continuity between window switch wiring
connector terminals and corresponding window motor wire connector
terminals of inoperative power window. If continuity exists in all
circuits, power window switch and switch circuits are okay. Check
power window motor. See POWER WINDOW MOTOR under COMPONENT TESTS. If
continuity does not exist in one or more circuits, repair open
circuit(s) as necessary. Recheck system operation.
Durango
1) Place window glass halfway between up and down positions.
Verify glass can be moved slightly from side to side, front to rear,
and up and down. If glass does not move freely, check window glass,
tracks and regulator for sticking, binding or improper adjustment.
Repair as necessary and recheck system operation. If glass moves
freely, and is not driver's window, go to next step. If driver's
window is inoperative, check power window motor. See POWER WINDOW
MOTOR under COMPONENT TESTS. If Auto Down feature is the only problem,
replace driver's switch. If switch LED is the only problem, replace
unlit switch.
2) Disconnect negative battery cable. Remove power window
switch from door with inoperative window. See POWER WINDOW SWITCH
under REMOVAL & INSTALLATION. Connect negative battery cable. Turn
ignition on. Check for battery voltage at power window switch harness
connector Yellow wire. If battery voltage does not exist, repair open
circuit to master window switch. If battery voltage exists, go to next
step.
3) Test power window switch continuity. See POWER WINDOW
SWITCH under COMPONENT TESTS. Replace faulty switch as necessary. If
switch is okay, go to next step.
4) Check for continuity in each circuit between master window
switch and switch for inoperative window. See WIRING DIAGRAMS. If
continuity does not exist in any circuit, repair open circuit as
necessary. If continuity exists in all circuits, test power window
motor. See POWER WINDOW MOTOR under COMPONENT TESTS.