Cargo 211091, User Manual

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211091
23
Vedpak 113_Version 2_201109
211091
22
Vedpak 113_Version 2_201109
Bench Tracing a Wire Harness
There are cases where you may have a wire harness
removed from the vehicle, sitting on the bench, and
tracing an open circuit. Wire harnesses that are removed
from the vehicle’s electrical system have only floating
wires in them. The open connectors of the harness are
connected neither to positive nor negative therefore
all of the harness’s circuits are open and floating. It is
important to be aware that the open circuit signal will
capacitive couple into floating circuits that run parallel
and next to the transmitting signal wire. (See Fig. A).
Floating circuits that couple the open circuit signal also
transmit the signal too and will even couple back to the
wire you want to trace. This prevents the receiver from
locating the break in the wire because all the wires are
transmitting signals. You can be easily led down the
wrong circuit if you are not aware of this.
To correct this problem, you need to tie all parallel
floating open circuits to either ground or a positive
voltage (See Fig. B).
All neighboring wires and circuits must have some
potential of ground or positive on them to prevent
capacitive coupling from occurring.
+ Voltage
Open circuit signal
+ Voltage
Open circuit signal
Not connected
Connected
Connected
Not connected
Fig. A Top and bottom wires are floating because they
are open. As you can see there are signals coupling into
them from the original circuit with the open circuit signal
injected into it.
Fig. B Top and bottom wires are now tied to positive or
negative and there is no capacitive coupling. The open
circuit signal now stops at the break in the wire.
It is recommended to trace OPEN circuits while the
IGNITION is turned ON. This will supply a positive
voltage on certain circuits that can potentially capacitive
couple. It is also a good idea to keep all of the vehicle’s
electrical loads (light bulbs, relays, motors etc. CON-
NECTED while tracing OPEN circuits. This keeps certain
neighboring circuits grounded, which also prevents them
from capacitive coupling.
Tracing out Battery Drains or Current Draw
When you have a battery or current draw that is drawing
enough current to drain the battery over night or a
couple of days, you have a condition that the tester can
assist you in. In cases like this you can inject a signal
into the main positive battery cable after removing it
from the positive battery post. Now you can follow the
signal along its path and look for the possible cause of
the battery drain.
Tracing battery drains is a little different than tracing
a short or open circuit. When you are tracing battery
drains you are not looking for a loss of signal, you are
simply following the circuit path and unplugging wires
and components along the way to give you clues to the
problem.
To trace battery drains and get nearer to the location of
the current draw:
1. Disconnect the positive terminal from the vehicle’s
battery. (You will need to consult your vehicle’s
owner manual for proper battery disconnecting
instruction. Some vehicles require that voltage
potential be maintained at all times on certain
components for instance radios, onboard computers,
memory, CPUs etc.).
2. Connect the transmitter’s 20 ft power lead to the
positive and negative post of the battery.
3. Connect the signal lead to the disconnected positive
terminal. Trace the circuit that is transmitting the
strong signal with the receiver. (The directional
indicators only show you the direction to ground. It
will not stop at the fault.)
4. Disconnect the wire and components along the circuit
path to narrow down the cause of the current draw.