MAC TOOLS EM721 - Sensor and Actuator Testing

800.MACTOOLS
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Watch the bargraph increase as the condenser charges. The resistance of a good condenser should increase
from zero to innity over a short period of time.
NOTE: In a conventional ignition system, make sure that the points are open before starting the test. Switch
the test leads and check the condenser in both directions. Check condensers under both hot and cold
conditions. The meter’s capacitance measurement function can be used to measure the capacitance
ofcondensers.
POSITION SENSORS
There are basically two types position sensors: Magnetic and Hall-Effect. The magnetic type is simply a
permanent magnet with a coil of wire wrapped around it. Magnetic sensors have two wires – one connected
to each end of a coil winding. Magnetic sensors can be found in some distributors and consist of a magnetic
pickup and a reluctor to change the magnetic eld. In a distributor, the clearance between the pickup and the
reluctor on a magnetic sensor is critical; be sure to check according to the manufacturer’s specications. The
specs are usually between 0.03 inches and 0.07 inches.
A Hall-Effect sensor uses a semiconductor material that produces a voltage as a magnetic eld passes
throughit. The voltage produced by the Hall-Effect sensor is proportional to the strength of the magnetic eld.
This magnetic eld can come from a permanent magnet or an electric current. Hall-Effect position sensors
have replaced ignition points in many distributor type ignition systems. They are also currently being used
to determine the crank and cam position on distributorless ignition system (DIS), which tells the vehicle’s
computer when to re the coils. This position information also tells the computer when to open the injectors
onsequential fuel injected systems.