Assessment Table For Sensor Tests; Sensor Installation Position Via Output Voltage; Sensor Operation - Porsche 928 Workshop Manual

Differential, Transaxle System 928
Assessment table for sensor tests
Test item I
Notes
Requirements
Fault I Troubleshooting
Sensor installation position
via output voltage
The sensor is supplied
with an input voltage of
5 volts across the ABS /PSD
control unit. The output volt-
age is 2.7 volts, provided that
the sensor is in a horizontal
position and fully operative.
- Specified reading:
2.7 f 0.14
volts when
the vehicle is
on a level surface
(ignition
is switched on).
If the reading exceeds or falls below the specification, this
means that the sensor bracket is bent or that the sensor is faulty.
If no voltage is displayed, the wiring has gone open circuit, the
sensor is faulty or an incorrect socket was used at the test lead.
Check wiring rouring according to wiring diagram if requried.
Some faults (open circuit I short circuit, sensor fault) are stored
in the fault memory of the ABS/PSD control unit. The fault mem-
ory (in PSD system) must therefore be read out with System
Tester 9288 and erased after the fault has been eliminated.
Sensor operation
To test, raise vehicle once at
front right and once at front left
by approx. 150 mm in each
case.
This must result in an exactly
predefined change of the volt-
age.
Use the above measurement
(initial reading obtained with
vehicle on level surface) as a
reference.
- Specified display:
Based on the initial reading,
the voltage must be higher when
the left side is raised and lower when the right side is
raised.
Example:
Initial reading
Raised at front left
Raised at front right
2.65 V
2.85 V
2.46 V
If the voltage does not change when the vehicle is raised (by
the same amount on left and right), this means that the sensor
is faulty.
Read out fault memory (in PSD system) with System Tester
9288 after eliminating the fault and erase the fault memory as
required.
D39 - 222
Lateral acceleration sensor
Printed in Germany XXXIV. 1994