Actron CP7011 - Manual (Page 2)

2
OxyGEN SENSOR
this sensor produces a voltage signal based on
the amount of oxygen it detects in the exhaust
stream. A low voltage (less than 0.4V) indicates a
lean exhaust (too much oxygen). A higher voltage
(0.6 - 1.0V) signals a rich exhaust (not enough
oxygen). the car computer uses the oxygen sensor
for fuel delivery attempting to maintain an ideal
air/fuel mixture for low emissions and good fuel
economy.
GAUGE OPERATION
NOTE: Typical Air/Fuel Ratio Gauge operation is described
below. The operation may vary from vehicle to vehicle.
the gauge measures the voltage produced by
the oxygen sensor and displays it in real time on
a radial, led (light emitting diode) bar graph.
the leds are color coded for ease of viewing and
interpreting the gauge reading.
When the headlights are turned on, the gauge
background illuminates and the leds are dimmed
for easy night viewing.
When the key is in the On position and the engine
is cold and not running, all segments of the gauge
are off.
When the engine first starts, all segments of the
gauge are off since the sensor needs to warm up to
its operating temperature. the exact time depends
on whether the oxygen sensor is heated (less than
a minute) or non-heated (several minutes) and the
vehicle. On some vehicles the gauge may read
lean right away.
When the sensor reaches its operating temperature,
but the engine still has not reached the operating
temperature when the car computer takes over
(open loop), the gauge will most likely read rich.
When the engine is controlled by the car computer
(closed loop) and the car is cruising, the gauge
segments will swing between rich and lean. On
vehicles with an added oxygen sensor that do not
have a computer the gauge reading will change
depending on the engine condition, but will not
constantly swing like on the computer-controlled
vehicles.
When the throttle is open during heavy load, the
readings will move toward rich.
during deceleration, the readings will be in the lean
zone. during a hard deceleration, the computer
might lean out the mixture to the point where no
led segments will be lit.
TROUbLESHOOTING
A sluggish response of the Air/Fuel ratio gauge
may indicate a partially fouled oxygen sensor. If
the sensor degradation is confirmed, the sensor
should be replaced. A lean operation under load
is a sign of improperly functioning fuel delivery
system. this can lead to engine damage.Persistent
rich operation (not under heavy load) can lead to
poor fuel economy, fouled spark plugs, and poor
performance.
Figure 2
General Hookup
OXYgen
SenSOr
COnneCtOr
CA
r
COMPU
ter
tO HeAd lAMPS
Or tAIl lIgHtS
HeAdlAMP
SWItCH
+12V
POWer
tO engIne
blOCk grOUnd
bl
AC
k
green
WHIte
AIr/FUel gAUge
FUSe
bOX
red
Figure 3 -
1, 2, 3 & 4 - Wire Sensors
1-WIre
OXYgen SenSOr
2-WIre
OXYgen SenSOr
3-WIre
OXYgen SenSOr
COnneCt gren WIre
On AIr/FUel gAUge tO
SenSOr SIgnAl WIre
4-WIre
OXYgen SenSOr
grOUnd
grOUnd
SenSOr SIgnAl
SenSOr SIgnAl
SenSOr SIgnAl
SenSOr grOUnd
HeAter POWer
HeAter grOUnd
SenSOr grOUnd
HeAter POWer
SenSOr SIgnAl
HeAter grOUnd
Figure 4
Oxygen Sensor Operation