36
EFI System
KohlerEngines.com
66 690 14 Rev. A
Temperature/Manifold Absolute Pressure (TMAP)
Sensor
A sealed non-serviceable integrated sensor that checks
both intake air temperature and manifold absolute
pressure. Complete replacement is required if it is faulty.
Sensor and wiring harness can be checked as follows.
If a blink code indicates a problem with Intake Air
Temperature (TMAP) Sensor Circuit (P0112 or P0113), it
can be tested as follows:
1. Remove TMAP sensor from intake manifold.
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 1850-2450
Ω
.
5. Unplug sensor from wire harness and check sensor
resistance separately across pin. Resistance value
should again be 1850-2450
Ω
.
a. If resistance is out of speci
fi
cations, check local
temperature. Sensor resistance will go down as
temperature is higher. Replace TMAP sensor if
determined to be faulty.
b. If it is within speci
fi
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 #3 in sensor plug. Continuity should be
indicated. Repeat test between Black pin 10 and
terminal #4 in sensor plug.
7. Reinstall
sensor.
If a blink code indicates a problem with Manifold
Absolute Pressure (TMAP) Sensor Circuit (P0107 or
P0108), it can be tested as follows:
1. Make sure all connections are making proper
contact and are free of dirt and debris. Slide locking
tab out and pull o
ff
TMAP connector. Turn key switch
to ON and check with a volt meter by contacting red
lead to pin 1 and black lead to pin 2. There should
be 5 volts present, indicating ECU and wiring
harness are functioning.
2. Check continuity in wire harness. Ohms between Pin
3 at sensor connector and Black pin 11 connector at
ECU should be near zero ohms. If no continuity is
measured or very high resistance, replace wire
harness.
3. Check to make sure intake manifold is not loose and
TMAP sensor is not loose. Loose parts would allow
a vacuum leak, making TMAP sensor report
misleading information to ECU.
a. Tighten all hardware and perform an ECU Reset
and a TPS Learn Procedure to see if MIL will
display a fault with sensor again. If MIL
fi
nds a
fault with TMAP sensor, replace it.
Oxygen Sensor (O
2
)
Components
Pin D
Pin C
Pin B
Pin A
Cutaway Oxygen Sensor Components (O
2
)
A
B
C
D
E
F
G
A
Protection Shield
B
Planar Element
and Heater
C
Lower Insulator
D
Stainless Steel
Housing
E
Upper Insulator
F
Terminal Connection
to Element
G
High Temp
Water Seal
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 di
ffi
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 e
ff
ective 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.
