NI 9757 User Manual
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© National Instruments
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7
Narrow-Band Oxygen Sensor Inputs
The NI 9757 provides four identical zirconium-dioxide-element, narrow-band (switching)
Exhaust Gas Oxygen (EGO) sensor inputs and supports several different types of standard
zirconium-oxide-element oxygen sensors, also known as lambda sensors. NI recommends that
you use a 4-wire heated universal EGO sensor, such as the Bosch USA 15717.
Note
This document discusses EGO sensor wires in terms of standard EGO
sensors, which use a standardized wire color code. OEM-specific EGO sensors might
use different wire color code.
4-Wire Heated EGO Sensors
4-Wire heated EGO sensors have a black and gray wire and two white wires. The black and gray
wires provide a differential lambda signal. Connect the black wire to the EGO+ pin of the
NI 9757 DB-37 connector. Connect the gray wire to one of the EGO- pins for the associated
channel of the NI 9757 DB-37 connector. The two white wires connect to a resistive heater
element inside the EGO sensor. The NI 9757 does not provide connections for these wires.
Connect these to an external 12 V power source, as shown in Figure 3. You can power the wires
through a relay that is energized with the main ignition switch and optionally insert a
user-supplied 3 A fuse per sensor.
If you are using a non-standard EGO sensor with different wire colorings, you must first identify
the two wires that are connected to the heater element by testing for approximately 5
Ω
across
two of the wires. Any other wire combinations will have a much higher impedance
measurement. The remaining two wires are the differential lambda signal wires. You might need
to use trial and error to correct the lambda signal wiring polarity. The sensor will not be damaged
if the wire polarity is reversed, but the sensor will not provide a correct reading and will likely
appear as a cold sensor in the software.
Figure 3.
4-Wire Heated EGO Sensor Connection
VMx (Y)
Blue
2
Yellow
IPx (R)
Red
1
Red
Module Pin Label
Intermediate
Cable Wire Color
LSU 4.9
Pin Number
LSU 4.9
Wire Color
