Actron AutoTroubleShooter CP7677 - Manual (Page 23)

23
Magnetic Pick-Up Coils – Reluctance Sensors
Reluctance sensors are used whenever
the vehicle computer needs to know
speed and position of a rotating object.
Reluctance sensors are commonly used
in ignition systems to determine cam-
shaft and crankshaft position so the ve-
hicle computer knows the optimum time
to fire the ignition coil(s) and turn on the
fuel injectors. This test checks the reluc-
tance sensor for an open or shorted coil.
This test does not check the air gap or
voltage output of the sensor.
Test Procedure (see Fig. 28):
Reluctance
Sensor
Red
Black
1. Insert BLACK test lead into COM
test lead jack.
2. I n s e r t R E D t e s t l e a d i n t o
test lead jack.
Reluctor
Ring
Magnet
3. Connect RED test lead to either
sensor pin.
4. Connect BLACK test lead to re-
maining sensor pin.
5. Turn multimeter rotary switch to
2K
Ω
range.
6. View reading on display while flex-
ing sensor wires in several places.
• Typical resistance range is 150 -
1000
Ω
.
• Refer to vehicle service manual for
your vehicles resistance range.
• As you flex sensor
w i r e s , t h e d i s p l a y
should remain steady.
7. Test Results
Good Sensor: Display
reading is within manu-
facturers specification
a n d r e m a i n s s t e a d y
while sensor wires are
flexed.
Bad Sensor: Display
r e a d i n g e r r a t i c a l l y
changes as sensor wires
are flexed or display
reading is not within
manufacturers specifi-
cation.
Fig. 28