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INTRODUCTION
AND MASTER TROUBLESHOOTING
- t+mwtions
Before
Service
'I3
DOING SERVICE WORK IN GROUPS OF TWO OR
MORE TECHNICIANS
If the service work is to be done by two or more technicians
working
together,
extra caution
must
be taken.
NOTE ON INSTALLATION OF RADIO EQUlPM$ihl-
The computers
of the electronic
control
system
has been
designed
so that external
radio waves will not interfere
with
their operation.
However,
if antenna
or cable
of amateur
transceiver
etc. is
routed
near the computers,
it may affect the operation
of the
computers.
even if the output
of the transceiver
is no more
than 25W.
To protect
each
of the
computers
from
interference
by
transmitter
(hum,
transceiver,
etc.). the following
should
be
observed.
1. Install
the antenna
on the roof or rear bumper.
2.
Because
radio waves are emitted
from the coaxial cable of
the
antenna,
keep
it 200
mm
(8 in.) away
from
the
computers
and the wiring
harness. If the cable must cross
the wiring
harness, route it so that it runs at right angles to
the wiring
harness.
3. The antenna
and the cable should
be well matched,
and
the standing-wave
ratio"
should
be kept
low.
4.
A transmitter
having a large output
should
not be installed
in the vehicle.
5. After installation
of transmitter,
run the engine at idle, emit
radio waves from the transmitter
and make sure that the
engine
is not affected.
*STANDING-WAVE
RATIO
If an antenna
and a cable
having
different
impedances
are
connected,
the input
impedance
Zi will vary in accordance
with
the
length
of the
cable
and
the
frequency
of the
transmitter,
and
the
voltage
distribution
will also vary in
accordance
with
the location.
The
ratio
between
this
maximum
voltage
and
minimum
voltage
is called
the
standing-wave
ratio.
It can also be
represented
by the
ratio
between
the impedances
of the
antenna
and the cable.
The amount
of radio waves emitted
from the cable increases
as the standing-wave
ratio increases,
and this increases
the
possibility
of the
electronic
components
being
adversely
affected.
1 TSB Revision
I
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Troubleshooting
