|
PRINCIPLE OF
OPERATION
Remember grade school math class and
fractions? Most people figured that they "would never use
that stuff'. Well here is a case where you will. I will explain
this in the simplest terms possible. If you have
a PHD in math, bear with the rest of us.
SpeedChanger® is simply the electronic
equivalent of a fraction. You give it a number of pulses
(frequency) by feeding it a signal from the wheels or
transmission sensor, on board computer or whatever.
You can then multiply and divide
that frequency signal to make it correct for what your
speedometer or on board computer requires. Sound simple enough?
MAKING
THE CONNECTIONS POWER CONNECTIONS
NEGATIVE POWER
CONNECTION - Connect the Negative (-) Power, BLACK wire, of the
SpeedChanger® to a Negative power point on the vehicle. This
point should be connected to the ground near or on the on-board
computer if you have one in this part of the system.
The next best choice would be on
the instrument cluster ground. Do not ground to the engine.
Attaching to a grounding point too far away may introduce
"noise" (stray signals) into the system. Noisy connections will
result in unwanted "bouncing" or "thumping" of the speedometer.
In other words don't ground
this thing to the trailer hitch and expect to pick up one (1)
volt signals under the hood. Keep your wires short and neatness
definitely counts.
DO NOT LET STRA Y STRANDS OF WIRE
REMAIN OUTSIDE OF THE CONNECTION AS THEY MA Y SHORT OUT THE MA
TERIALS. NEA TNESS DEFINITL Y COUNTS! REMEMBER THE 30 SECOND
RULE.
POSITIVE POWER CONNECTION
Connect the Positive (+) Power, RED wire,
of the
SpeedChanger® to a FUSED power source that is only active when
the ignition switch is in the "RUN" or "RUN & START" condition.
SpeedChanger® only requires a few
milliamps and will not require a different (larger) fuse to be
used if SpeedChanger® is connected to an existing circuit such
as the engine computer
or
instrument cluster circuits.
GETTING A
GREEN LIGHT
When the
Negative and Positive have
been connected correctly and
power (key) is turned on, the GREEN PILOT
LIGHT, located in the middle of SpeedChanger®, will
light indicating that
SpeedChanger® is on. At this point
it is safe to turn on the power and check
your connections. If everything is OK and you have a
green light switch the power off and continue with these
directions.
If you don't get a green
light check your connections especially the polarity and
retry. You may need to
use a voltmeter to determine why
the power is not getting to SpeedChanger®.
FINDING THE SPEED SIGNAL WIRE IN YOUR
VEHICLE
The SPEED SIGNAL WIRE on the vehicle will
need to be located at this point. The easiest way to
locate this wire is to look it up in the electrical repair
manual for your particular vehicle.
This can be gotten from most auto
parts stores and dealerships. We are continually adding diagrams
for vehicles to our web
page vehicle applications section on www.terf.com or
www.speedchanger.com.
For vehicles with simpler electrical
systems like racecars or older vehicles you may be able to
identify the wire simply by looking at the
system components like the back of the speedometer.
It is better to keep the SpeedChanger® unit
mounted inside of the vehicle to protect it from the
elements,
especially in harsher climates. SpeedChanger® should NEVER be
mounted next to exhaust
components or turbo
chargers or any other component that produces extreme heat as
this could damage
SpeedChanger® and void the warranty.
The easiest way
to find the SPEED SIGNAL WIRE on the vehicle is to look for the
SPEED SIGNAL SENSOR. This sensor is typically located on the
tail end of the transmission.
If this is the
case follow the wire into the vehicle or bring a pair of wires
from the inside of the vehicle where the SpeedChanger® is to be
mounted out to the SPEED SIGNAL SENSOR outside of the vehicle.
BEFORE YOU
CUT ANY WIRES
Take a stickpin
and poke it through the insulation, or in some other manner,
connect the wire you have determined to be the SPEED SIGNAL WIRE
on the vehicle to the SIGNAL INPUT, Orange wire on the
SpeedChanger® unit. (See SIGNAL INPUT connections below.)
Rotate the wheels
on the vehicle and determine if the input YELLOW light on the
SpeedChanger® flashes in time with this movement. This will
determine if in fact you have the right wire and save you from
making wire patches for cutting the wrong wires.
Remember to turn
on the Ignition and confirm that you have a GREEN light on the
SpeedChanger® unit.
Be sure that the
TEST Oscillator switch is moved toward the right, center of the
box, or "RUN" position.
The engine need
not be running for this operation. If you connect the
SpeedChanger® unit to the wrong wire, no damage will result to
either the SpeedChanger® unit or the other components in your
vehicle.
Included in
the Appendix of this document are some more advanced wiring
diagrams of how vehicle systems are constructed. This may help
in finding the proper wire for your application.
The basic concept
is to find the SPEED SIGNAL WIRE, positive or active, on the
vehicle and CUT the wire so that the SpeedChanger® unit can
modify the signal as it passes from the speed sensor (or source
such as the computer) to the speedometer (or computer).
If you are working
with a system with more than one wire, cut the "HOT" or active
side. Connect the Sensor or Input side of the cut wire from the
vehicle to the SIGNAL INPUT, Orange wire, of the SpeedChanger®.
Connect the other
wire you have created in the CUT to the SIGNAL OUTPUT, White
wire, of the SpeedChanger®. Leave the SPEED SENSOR NEGATIVE wire
or groundside wire (VSS negative) on the vehicle factory
connected unless you find that the use of the SPEED SIGNAL WIRE,
positive or active, on the vehicle alone will not work.
Typically the
ground for the speed sensor and the ground for the vehicle are
common and the SpeedChanger® will get this information from the
POWER GROUND, Black wire, connection.
For late model
vehicles with advanced electronic computer controls, you have an
option here. The SPEED SIGNAL WIRE actually passes from the
speed sensor to (a speed modifier box (in the case of GM pickups
for example)) the engine computer then to the speedometer. If
you place SpeedChanger® between the computer and the speedometer
all you change is the speedometer reading.
If you place
SpeedChanger® between the speed sensor and the engine computer
you modify everything the engine computer uses the speed signal
for.
This may include
transmission shift points, engine operation limits, vehicle
maximum speed limits (for tire overrev safety), cruise control,
active steering, etc.
This may be
advantageous if you find these systems are not reacting
correctly due to the inaccuracy in your current configuration BE
SURE THAT THE ENGINE COMPUTER DOES NOT FEED SPEED INFORMATION TO
AIRBAG OR ANTILOCK BRAKE CONTROLS IF YOU CHOOSE TO MODIFY THE
SIGNAL BEFORE THE ENGINE COMPUTER.
Ask your dealer
for more information and/or look for alternative input sensors
at each wheel for the antilock brake system.
This is important.
If this is the case you must modify the speed signal after the
engine computer, affecting only the safe systems indicated.
SIGNAL INPUT CONNECTIONS:
SIGNAL INPUT POSITIVE
CONNECTION
Connect the Signal Input Positive, ORANGE wire, to
the signal source, such as the speed sensor or computer.
SpeedChanger® was
designed with a very special input circuit that automatically
adjusts itself to virtually any input signal. SpeedChanger® will
read VR Magnetic Sensors, Hall Effect Digital Sensors, computer
generated signals all without making any adjustments to the
unit.
You may need to
determine which wire is the "HOT" or positive signal wire of a
system, such as a VR Sensor. The best way to determine the
correct connection is to simply connect the Signal Input
Positive, ORANGE wire, to one of the two speed sensor wires on
the vehicle.
If the YELLOW
light on the SpeedChanger® flashes when the
wheels
are moved you are done. If not, connect the Signal Input
Positive, ORANGE wire, to the other
speed sensor wire on the vehicle. And repeat the test by
spinning the wheels.
You will generate
a signal that will be read and result in a flashing YELLOW light
on the SpeedChanger® unit. Often times this wire is labeled in
vehicle technical manuals as VSS positive for Vehicle Speed
Signal Positive if you have such a manual at your disposal.
This device is
designed not to damage any of the vehicle components if you do
not make the correct connection. This input is a very "high
impedance" or looks nearly invisible to the
vehicle
systems.
If
you are adding this unit to a "stock system" the VSS negative
(Vehicle Speed Signal negative)
connection will already be made. If you have a new installation
as with a racecar or the like you may need to make this
connection.
If you have a
simple VR Sensor simply connect the "other sensor wire" to
negative
or ground. See the diagrams
in the Appendix for other installations and techniques.
GETTING A YELLOW
LIGHT
When
the Signal Input Positive is
received correctly the YELLOW SIGNAL INPUT LIGHT (on the left
side above the wires) on the SpeedChanger® will flash once with
every input
pulse that is received.
SpeedChanger® can also be tested independently of an input
signal by
moving the "TEST OSCILLATOR" switch to the TEST INPUT position.
This
places an internal 50 Hz
oscillator to the input and stimulates the system.
OBVIOUSLY, THE SWITCH MUST BE PLACED IN THE "RUN" POSITION
FOR
THE UNIT TO FUNCTION IN YOUR SYSTEM. It will not be necessary
for the engine to be running at this point.
SIGNAL
OUTPUT CONNECTIONS:
SIGNAL OUTPUT CONNECTION - The Signal Output, WHITE wire,
provides a square wave
output voltage that varies from near the Positive Power Input to
the Negative Power Ground value.
(For you technical
types the output is shown in the figure attached.)
This
SIGNAL OUTPUT has several advanced features unique to this
product:
First, the output is protected against being connected directly
to the Positive Power Input.
Normally this would instantly "roast" SpeedChanger®.
SpeedChanger® has
been equipped with an AUTOMATIC RESETTING CIRCUIT BREAKER.
This circuit
breaker turns off the Signal Output from the SpeedChanger® in
the event that too much current is being drawn. Keep this in
mind if you try to overload the maximum instantaneous output
rating of SpeedChanger®.
No damage will
occur, however no signal will be provided either. The circuit
breaker resets itself several times every second so there is no
delay in
operation once the problem
is rectified.
Secondly, this unit has a feature that stops the Signal Output
when no Signal Input is received.
This has no effect
on the speedometer reading. The minimum speedometer reading is
typically >5MPH. SpeedChanger® is designed to give an output
minimum -4MPH.
This feature is
activated at a frequency
typically below 2MPH.
This
feature DOES stop the Odometer from logging miles while the
vehicle is not moving.
Otherwise
SpeedChanger® would output the -4MPH while setting at lights or
any time the ignition is in the
"RUN" position.
These miles can add up over
time so we have added this advantage.
GETTING A RED LIGHT
A RED
Light (on the left side of SpeedChanger® above the wires)
indicates an Output Signal.
When the
Output Signal is "pulled low" or connected to NEGATIVE GROUND by
SpeedChanger® (or externally by connecting the output to
NEGATIVE GROUND) the RED Light is activated.
This RED
Light will blink at low
frequencies. As the frequency increases the light will APPEAR to
be on
constantly.
NEXT PAGE |
