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EFI System
Crankshaft Position Sensor
A sealed, non-serviceable assembly. If Fault Code
diagnosis indicates a problem within this area, check
and test as follows.
1. Inspect wiring and connections for damage or
problems.
2. Make sure engine has resistor type spark plugs.
3. Disconnect Black connector from ECU.
4. Connect an ohmmeter between #4 and #13 pin
terminals. A resistance value of 325-395 Ω at room
temperature (20°C, 68°F) should be obtained.
5. If resistance is incorrect remove blower housing.
6. Disconnect crankshaft position sensor connector
from wiring harness. Test resistance between
terminals. A reading of 325-395 Ω should again be
obtained.
a. If resistance is incorrect, remove screw securing
sensor to mounting bracket and replace sensor.
b. If resistance in step 4 was incorrect, but
resistance of sensor alone was correct, test wire
harness circuits between sensor connector
terminals and corresponding pin terminals (#4
and #13) in main connector. Correct any
observed problem, reconnect sensor, and
perform step 4 again.
7. If resistance is correct from step 4, check mounting,
fl ywheel teeth (damage, run-out, etc.) and fl ywheel
key.
8. When fault is corrected and engine starts, clear fault
codes and follow ECU Reset procedure.
34
Throttle Position Sensor (TPS)
TPS is a sealed, non-serviceable assembly. If diagnosis
indicates a bad sensor, complete replacement is
necessary. A magnet that sensor detects is separate,
and can be replaced or reused. If a blink code indicates
a problem with TPS, it can be tested as follows:
Diagnostics of sensor: ECU will have electrical faults
captured in fault codes P0122 and P0123. Fault code
P0122 detecting low voltage, open circuit, and P0123 for
high voltage conditions between ECU, wire harness, and
sensor. Tip: when working with any electrical connection,
remember to keep connections clean & dry. This is best
accomplished by cleaning connection thoroughly prior
to disassembly. Contaminated sensor connections can
cause premature engine faults. Functionally testing
sensor can no longer be done with simple resistance
checks. If either of these two faults is present or a TPS
fault is suspected, recommended diagnostic test is as
follows:
If a computer with diagnostic software is available
Observe throttle percent and raw TPS values through
diagnostic software. With diagnostic software
communicating to ECU and key ON engine not running,
these values can be observed while throttle is moved
from closed to full open position. There should be a
smooth and repeatable throttle percent value starting at
closed position reading between 0% to WOT position
of 100%. If one of these values is outside of specifi ed
range and output transitions in a smooth manner, reset
ECU and run test again. Since there is no longer any
wear elements inside sensor, most likely faults will
be in electrical connections between sensor and wire
harness and wire harness to ECU. With service software
communicating to ECU and engine not running, a small
load or gentle back and forth motion can be applied to
connectors or wires just outside connectors to detect a
faulty connection.
If only a volt meter is available
Measure voltage supply to sensor from ECU. This
voltage should be 5.00 +/- 0.20 volts. This can be
measured by gently probing terminals B & C on harness
side with TPS connector removed from TPS and key
ON. This will generate a P0122 fault that can be cleared
with an ECU reset. If voltage is low, battery, harness and
ECU should be investigated. If supply voltage is good,
plug sensor back into harness. Probe sensor signal
wire with volt meter, terminal A at TPS or pin Black 12 at
ECU. This signal should start between 0.6-1.2 volts at
low idle and grow smoothly as throttle is opened to 4.3-
4.8 volts at full open (WOT). Since there is no longer any
wear elements inside sensor, most likely faults will be in
electrical connections between sensor and wire harness
and wire harness to ECU.
KohlerEngines.com
66 690 14 Rev. A
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