Removal Of The Steering Angle Sensor - PREVOST H3-41 Maintenance Manual

Yaw stability counteracts the tendency of a
vehicle to spin about its vertical axis. During
operation, if the friction between the road surface
and the tires is not sufficient to oppose lateral
(side) forces, one or more of the tires can slide,
causing the vehicle to spin. These events are
referred to as either an "under-steer" situation
(where there is a lack of vehicle response to
steering input due to the slide on the front axle)
or an "over-steer" (where the vehicle's rear end
slides out due to tire slide on the rear axle)
situation. Factors that influence yaw stability are:
wheelbase, suspension,
weight distribution front to rear, and vehicle track
width.
Yaw Control
Yaw Control corresponds to a wide range of low
to high friction surface scenarios including
rollover, jackknife and loss of control. It is the
recommended system for all power vehicles and
especially critical for vehicles pulling trailers. In
the case of vehicle slide (over-steer or under-
steer situations), the system will reduce the
throttle and then brake one or more of the "four
corners" of the vehicle (in addition to potentially
applying the trailer brakes), thus applying a
counter-force to better align the vehicle with an
appropriate path of travel.
For example, in an over-steer situation, the
system applies the "outside" front brake; while in
an under-steer condition, the "inside" rear brake
is applied.
23.4 BENDIX SAS-70 STEERING ANGLE
®
SENSOR
The Steering Angle Sensor (SAS) is used to
provide driver steering input to the controller. It
reports the steering wheel position to the
controller utilizing a dedicated serial communica-
tions link that is shared with the YAS-70 sensor.
The controller supplies the power and ground
inputs to the SAS-70 sensor.
The SAS-70 sensor installed on Prevost vehicles
is the 90° connector.

23.4.1 Removal of the steering angle sensor

Service Checks:
1. Check all wiring and connectors. Some
installations also include an intermediate
steering geometry,
PA1621 Maintenance Manual All Series | Revised June 2020
SECTION 12: BRAKE AND AIR SYSTEM
connector from the steering angle sensor to
the main vehicle wire harness. Make sure all
connections are free from visible damage.
2. Examine the sensor. Make sure the sensor,
its mounting screws, and the interface
between the hub and the steering column
are not damaged.
Diagnostics:
The steering angle sensor is only operational in
conjunction with an EC-80 ECU. No independent
diagnostics can be performed on the sensor.
Removal:
1. Remove steering column upper, middle and
lower covers.
2. The steering angle sensor is located near
the universal joint.
3. Unplug sensor cable assembly from body of
sensor. Squeeze the mounting tabs and pull
gently on connector until it disengages.
4. Disconnect steering column upper U-joint.
5. Unscrew all three of the mounting screws
that hold the body of the sensor to the
steering column body.
6. Slide the sensor over the column to remove.
Take note if the sensor label is facing up-
ward or downward.
Installation:
1. Obtain a new sensor. The sensor is not
repairable in the field.
2. Slide the sensor over the column. The
center hub of the sensor must be aligned
with the corresponding notch in the column.
The sensor label should be facing in the
same direction as the removed sensor.
TORQUE: 9-12 lb-in (1,02-1,36 Nm)
3. Reconnect the steering column U-joint.
TORQUE: 35-39 lb-ft (47-53 Nm)
4. Reconnect the connector. Ensure that there
will be no force applied to the sensor
because the connector is pulling on the
sensor body.
5. If the wire harness leading to the sensor is
being replaced, ensure that it is adequately
tie wrapped so that the full motion of the
steering column can be achieved without
pulling apart the connectors.
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