TP-6391 9/08 55Section 5 Component Testing and Adjustment
Crankshaft Position Sensor
The crankshaft position sensor monitors speed control,
timing (firing of spark plugs), and fuel injection. See
Figure 5-16 for the crankshaft position sensor location.
The crankshaft position sensor is an electromagnetic
device which contains a permanent magnet surrounded
by a winding. The sensor is used with the timing wheel.
The timing wheel has 30 gear teeth with 5 teeth removed
at precise locations allowing the ECM a very accurate
speed reference signal. The timing wheel rotation near
the sensor’s tip changes the magnetic flux, creating an
analog voltage signal in the sensor coil.
The spark is sent to the appropriate cylinder via the rotor
arm and spark plug wires. The ECM uses the signal
from the crankshaft position sensor to determine the
engine position and RPM. This information, together
with the TPS and TMAP sensor information is used to
calculate the correct ignition timing settings.
To test the crankshaft position sensor, set the generator
set master switch to the OFF position and allow the
generator set to cool. Disconnect the crankshaft
position sensor and use an ohmmeter to measure the
resistance across the sensor pins. See Figure 5-18.
Ignition Coil
This system uses a single coil incorporating the ignition
driver circuitry inside the coil. See Figure 5-19. The
ECM signals the coil to begin its cycle. Then the coil
waits for the trigger signal from the ECM.
To test the ignition coil, set the generator set master
switch to the OFF position and allow the generator set to
cool. Disconnect the ignition coil and use an ohmmeter
to measure the resistance across the coil pins. See
Figure 5-20 for the coil resistance.
1
GM39685B-J
1. Crankshaft position sensor
Figure 5-16 Crankshaft Position Sensor Location
Model Crankshaft Position Sensor Gap
All 0.030--0.060 in.
Figure 5-17 Crankshaft Position Sensor Gap
Crankshaft Position Sensor Pin Resistance (approx.)
Pin 1 (+) to Pin 2 (--) 320 Ohms
Figure 5-18 Crankshaft Position Sensor Resistance
Check
Figure 5-19 Ignition Coil
Ignition Coil Pin Resistance Check (approx.)
Pin A (SIGNAL) to Pin B 10 kOhms
Pin A (SIGNAL) to Pin D 34 kOhms
Pin A (SIGNAL) to Pin E (PWR) 15 kOhms
Pin B to Pin D 44 kOhms
Pin B to Pin E (PWR) 26 kOhms
Pin D to Pin E (PWR) 17 kOhms
Figure 5-20 Ignition Coil Resistance Check
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