Neon L4-2.0L SOHC (1995)
Crankshaft Position Sensor: Description and Operation
No Crank Reference Signal at PCM
NAME OF CODE:
No Crank Reference Signal at PCM
WHEN MONITORED:
During engine cranking, with battery voltage less than 11.5 volts and manifold vacuum present.
SET CONDITION:
No signal from the crankshaft position (CKP) sensor during engine cranking or there is a camshaft position sensor signal without a CKP sensor
signal.
THEORY OF OPERATION:
The crankshaft position sensor is a hall-effect type sensor used to detect the crankshaft's speed and position. The Powertrain Control Module
(PCM) supplies 8 volts and a sensor ground to the CKP sensor. The crankshaft position sensor signal circuit has a 5-volt pull-up from the PCM.
The sensor signal is created by the notches in the crankshaft pulse ring passing under the sensor. When a notch is under the sensor, the signal
remains at 5 volts. When there isn't a notch under the sensor, the signal drops to 0.3 volt.
POSSIBLE CAUSES:
-
Open or shorted 8-volt supply circuit
-
Open sensor ground
-
Open or shorted signal circuit
-
Excessive clearance between the sensor and crankshaft pulse ring
-
Damaged crankshaft pulse ring
-
Failed sensor
-
Failed PCM
-
Connector terminals
-
Connector wires
