The notches generate pulses from high to low in
the crankshaft position sensor output voltage. When
a metal portion of the counterweight aligns with the
crankshaft position sensor, the sensor output voltage
goes low (less than 0.5 volts). When a notch aligns
with the sensor, voltage goes high (5.0 volts). As a
group of notches pass under the sensor, the output
voltage switches from low (metal) to high (notch)
then back to low.
CRANKSHAFT POSITION SENSOR—2.5L
DESCRIPTION
The crankshaft sensor is located on the rear of the
transmission housing, above the differential housing
(Fig. 9). The sensor connector has a christmas tree
attached to the heater tube bracket. The bottom of
the sensor is positioned next to the drive plate.
OPERATION
The crankshaft position sensor (Fig. 10) detects
slots cut into the transmission driveplate extension.
There are 3 sets of slots. Each set contains 4 slots,
for a total of 12 slots (Fig. 11). Basic timing is set by
the position of the last slot in each group. Once the
Powertrain Control Module (PCM) senses the last
slot, it determines crankshaft position (which piston
will next be at TDC) from the camshaft position sen-
sor input. The 4 pulses generated by the crankshaft
position sensor represent the 69°, 49°, 29°, and 9°
BTDC marks. It may take the PCM one engine rev-
olution to determine crankshaft position.
The PCM uses crankshaft position reference to
determine injector sequence, ignition timing and the
presence of misfire. Once the PCM determines crank-
shaft position, it begins energizing the injectors in
sequence.
Fig. 8 Timing Reference Notches
Fig. 9 Crankshaft Position Sensor Location—Typical
Fig. 10 Crankshaft Position Sensor—Adjustable
JA IGNITION SYSTEM 8D - 5
DESCRIPTION AND OPERATION (Continued)
To Next Page
Loading...
