Chapter 6. Troubleshooting
STACK ST8130 Road Car Display System
58
Users Guide
No.
Symptom
Possible Cause
Remedy
Notes
23
Displayed speed
value too high or
too low by a
constant %-age
amount.
System configured
with wrong number
of targets per wheel
revolution
Reconfigure the
system with correct
values
System configured
with wrong
circumference.
24
No speed reading
Speed reading
erratic, value
jumps high or low
Faulty sensor
and/or wiring
Check sensor
indicator for correct
operation
Rotate the
wheel by hand
and check that
the sensor
indicator lights
up as each
target passes
the sensor
Incorrect sensor
gap (too far or too
close)
Check that the gap
is approximately
1mm / 40thou
ST8131
(ST670) only
Sensor and targets
moving apart
Fabricate a more
rigid sensor bracket
1.
Pulse amplifier
not connected
2.
Pulse amplifier
out of
adjustment
Rotate wheels and
check the LED on
the ST492 for
pulse signals
ST8130
(ST492) only
25
Speed reading
dies after a short
time
Ambient
temperature too
high
Shield the sensor
from radiated heat
from brakes and
bearings. Insulate
sensor from
conducted heat
with fibre washers.
Duct cooling air
around the sensor
Maximum
temperature for
correct
operation of the
wheel speed
sensor is +80
°
C
(175
°
F)
