Intake Air Temperature Sensor; Oxygen Sensor - Kohler ECV940 Service Manual

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. Carefully unseat both clips securing
main fuel line to air cleaner bracket to access sensor.
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 specifi cations, replace
temperature sensor.
b. If it is within specifi cations, 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.
7. Reinstall sensor and reposition main fuel line back
into clips on air cleaner bracket.
Oxygen Sensor (O )
2
Components
Pin D
Cutaway Oxygen Sensor Components (O
62 690 05 Rev. --
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 fi eld.
Furthermore, as with most devices, intermittent problems
are diffi cult to diagnose. Still, with a good understanding
of system and sensor, it is possible to diagnose many
sensor problems in fi eld.
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
readings. Since resistance of sensor is highest at
low temperatures, such meters will cause largest
inaccuracies when sensor is in a cool exhaust.
Visual Inspection
Pin A 1. Look for a damaged or disconnected sensor-to-
engine harness connection.
Pin B
2. Look for damage to sensor lead wire or associated
Pin C
engine wiring due to cutting, chaffi ng 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.
2
KohlerEngines.com
D
E
C
A
B
Protection Shield B
Lower Insulator D
Upper Insulator F
High Temp
Water Seal
EFI SYSTEM
G
F
Planar Element
and Heater
Stainless Steel
Housing
Terminal Connection
to Element
29