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A
2: VSS C
PPENDIX
The DriveRight can work with many different VSS signals pro-
vided the switch settings of the VSS in-line circuit are set cor-
rectly. However, if the signal does not meet the specifications
below it may not work.
Page 12
enable the test circuit). The following other
methods can be used to see if you have the cor-
rect wire. In order of preference:
❏ Use a portable oscilloscope and verify the
square wave or sine wave VSS signal.
Watch the signal frequency change with
speed.
❏ Using a multimeter to measure the fre-
quency of the VSS pulse. Usually, the PPM
(pulses per mile) of the VSS signal is
known. At 40 km/hr (25 mph) the follow-
ing frequencies should be:
2000 PPM : 14 hz
4000 PPM : 28 hz
5000 PPM : 35 hz
8000 PPM : 56 hz
❏ A voltmeter can be used on square wave
signals to verify the 2 DC levels when the
vehicle is moved. Note, in most cases the
vehicle must be running and driven
slowly to detect this change.
❏ Check with your local vehicle dealership to
make sure the vehicle make and model is
equipped with a complete VSS signal.
OMPATIBILITY
❏ Maximum VSS frequency at 25 mph is 1 khz
(144,000 PPM).
❏ Minimum peak to peak amplitude at 5 mph is
1 volt.
❏ Maximum peak to peak amplitude is 25 volts.
❏ Input Impedance of VSS inline-circuit is 22k.
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