4.4 Other sensors 4 WIRING
• Four wires: These have a signal wire and a sensor ground wire which connects to the MS3Pro sensor ground
wire. The two heater wires are normally the same color. One connects to a switched 12 volt source and the
other can be grounded to the engine block or chassis.
As a general rule, if the sensor has two wires that are the same color, these two wires are for the heater, and may
be hooked up either way. Bosch’s wire coloring system is the most common, and looks like this:
Function Color
Signal Black
Sensor ground Gray
Heater White
Heater White
However, there are several other color schemes out there; if you run into a different set of colors, consult a
factory wiring diagram for your vehicle.
The MS3Pro can also work with most aftermarket wideband oxygen sensor controllers. You will need to install
the controller according to the directions that came with it, and connect the controller’s analog output wire to the
MS3Pro’s oxygen sensor input wire. If the wideband controller has a ground specifically for its analog output, it
connects to the MS3Pro sensor ground wire. Do not connect any wires labeled “serial output”, “digital output” or
similar to the MS3Pro, or connect any other sort of wideband ground to the MS3Pro. Here is a list of what wire to
use with common wideband controllers.
Controller Analog output Analog ground
Innovate LC-1 Brown * N/A
Innovate MTX-L Yellow * N/A
Innovate LM-2 Lime green* Yellow*
AEM UEGO White N/A
Zeitronix ZT-2, ZT-3 White Brown (ZT-2 only)
PLX SM-AFR Gray N/A
*Innovate systems have multiple analog outputs; this is the recommended default.
The above list is not intended to be a complete list of what wideband controllers will work with the MS3Pro;
it will work with many other ones not listed. As long as the wideband has a 0-5 volt analog output, and you can
obtain the specifications for its output, you can make it work with the MS3Pro.
Additional narrow band O
2
sensors or wideband controllers may be wired to the spare analog input wires.
The MS3Pro can also accept wideband oxygen sensor data over CAN. The CAN-EGT or other devices can
translate Innovate serial data into CAN data for the MS3Pro, and the MS3Pro can also receive CAN data from
wideband O
2
sensor controllers from AEM, EcoTrons, and 14Point7.
4.4.6 Knock sensors
If you have a two wire knock sensor, connect one wire to the knock input wire and the other wire to the sensor
return. Some cars have three wire knock sensors; the third pin is a connection for a shield on the wire. If you’re
only using one knock sensor, connect it to Knock In 1. Knock sensors, like VR sensors, generate their own voltage
and do not require a power source.
The knock inputs are purpose built and will not work with any other type of sensor.
4.4.7 Speed and gear sensors
The MS3Pro can use analog or Hall effect speed sensors.
Analog speed signals are rare, but show up in some aftermarket speedometers. These produce out 0 volts with
the vehicle stopped, increasing to 5 volts at some top speed. These may be wired to any unused general purpose
analog input.
Hall effect speed sensors are more common. These get 12 volts from the switched power or 5 volts from VREF,
and have a ground wire that connects to the MS3Pro’s sensor ground. Using the digital frequency inputs will give
you the best response, but you can also use a digital switched input. No pull up resistor is required if using our
tabbed Hall effect sensor; we recommend a pull up when using our threaded Hall effect sensor. The MS3Pro can
use two separate speed sensors for driven and non-driven wheels.
AMP EFI MS3Pro manual version 1.202, firmware 1.5.0, 4/21/2017 Page 41
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