Speed Sensor - Jeep 1987 Wrangler Workshop Manual

m G
THROTTLE BODY FUEL INJECTION SYSTEM
T R G m G
GENERAL INFORMATION
T R G
Speed Sensor
T h e s p e e d sensor is attached to the flywheel/
drive plate housing.
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T h e s e n s o r detects the flywheel/drive plate
teeth a s they p a s s during engine operation and
provides engine s p e e d and crankshaft angle
information to the E C U .
T h e flywheel/drive plate h a s a large trigger tooth
and notch located 90 degrees before e a c h top
dead center ( T D C ) position.
There are 12 small teeth between the notch and
T D C .
12 11 ™
87049A
When a small tooth and notch p a s s the magnet
core in the sensor, the concentration and then
collapse of the magnetic flux induces a small
voltage (spike) into the s e n s o r pick-up coil
winding.
T h e s e small voitage spikes enable the E C U to
count the teeth a s they p a s s the sensor.
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