Kohler Command PRO ECV630 Service Manual page 32

EFI SYSTEM-ECV
6. Check circuits (input, ground), from wire harness
connector to sensor plug for continuity, damage, etc.
Connect one ohmmeter lead to Black pin 14 in wire
harness connector (as in step 4). Connect other lead
to terminal #1 in sensor plug. Continuity should be
indicated. Repeat test between Black pin 10 and
terminal #2 in sensor plug.
Intake Air Temperature Sensor
A non-serviceable component. Complete replacement is
required if it is faulty. Sensor and wiring harness can be
checked as follows.
1. Remove temperature sensor from throttle body.
2. Allow it to reach room temperature (20°C, 68°F).
3. Unplug Black connector from ECU.
4. With sensor still connected, check temperature
sensor circuit resistance between Black pin 10 and 8
pin terminals. Value should be 3100-3900 Ω.
5. Unplug sensor from wire harness and check sensor
resistance separately across two pins. Resistance
value should again be 3100-3900 Ω.
a. If resistance is out of specifications, replace
temperature sensor.
b. If it is within specifications, proceed to Step 6.
6. Check circuits (input, ground), from main harness
connector to sensor plug for continuity, damage, etc.
Connect one ohmmeter lead to Black pin 8 in main
harness connector (as in step 4). Connect other lead
to terminal #1 in sensor plug. Continuity should be
indicated. Repeat test between Black pin 10 and
terminal #2 in sensor plug.
Oxygen Sensor (O )
2
Components
Pin D
32
Cutaway Oxygen Sensor Components (O
A
C
E
G
Temperature must be controlled very accurately and gas
constituents measured to a high degree of accuracy for
absolute sensor measurements. This requires laboratory
equipment to determine a good or bad sensor in field.
Furthermore, as with most devices, intermittent problems
are difficult to diagnose. Still, with a good understanding
of system and sensor, it is possible to diagnose many
sensor problems in field.
Using diagnostic software connected to ECU is a useful
technique for observing sensor performance. However,
user must understand that such software reads a signal
generated by ECU. If there is an ECU or wiring problem,
readings could be misinterpreted as a sensor problem.
Digital nature of signal to software means that it is not
reading continuous output of sensor. A voltmeter can
also be used as an effective tool in diagnosing sensors.
It is advisable to use an electronic meter such as a
digital voltmeter. Simple mechanical meters may place
a heavy electrical load on sensor and cause inaccurate
Pin A
readings. Since resistance of sensor is highest at
low temperatures, such meters will cause largest
Pin B
inaccuracies when sensor is in a cool exhaust.
Pin C
Visual Inspection
1. Look for a damaged or disconnected sensor-to-
engine harness connection.
2. Look for damage to sensor lead wire or associated
engine wiring due to cutting, chaffing or melting on a
hot surface.
3. Disconnect sensor connector and look for corrosion
in connector.
4. Try reconnecting sensor and observe if problem has
cleared.
5. Correct any problems found during visual check.
KohlerEngines.com
D
E
C
A
B
Protection Shield B
Lower Insulator D
Upper Insulator F
High Temp
Water Seal
)
2
G
F
Planar Element
and Heater
Stainless Steel
Housing
Terminal Connection
to Element
24 690 02 Rev. D