Electromagnetic Pickup Type - Toyota COMPUTER-CONTROLLED SYSTEM Training Manual

ELECTRONIC CONTROL SYSTEM - Vehicle Speed Senso r
3 . ELECTROMAGNETIC PICKUP TYP E
This sensor is fitted to the transmission and
detects the rotational speed of the transmission
output shaft.
This sensor consists of a permanent magnet, a
coil, and a core . A rotor with four teeth is
mounted on the transmission output shaft .
Rotor
N S i Magnet
OHP 3 0
+ V
OHP 30
0
- V
ELECTRICAL CIRCUITRY
OHP 3 0
Engine EC U
OHP 3 0
OPERATION
When the transmission output shaft rotates, the
distance between the core of the coil and the
rotor increases and decreases because of the
teeth .
The number of lines of magnetic force passing
through the core increases or decreases
accordingly, and AC (alternating current) voltage
is generated in the coil .
Since the frequency of this AC voltage is
proportional to the rotational speed of the rotor,
it can be used to detect the vehicle speed .
OHP 3 0
®
Coil Core Speed sensor
35