8.4 Fault Indication
Open Circuit
An open circuit fault warning is triggered when the circuit draws under 4mA of power. The Alpha MUTT
®
has a circuit detection resolution of 2mA. (A single LED with an LED bulb will draw 5-7mA of current.)
When the Alpha MUTT
®
senses no load, it is often a symptom of a disconnected wire, cut wire, poor pin
connection or bad return ground. The tester can detect open circuits in two ways.
1. During ground integrity test: An individual circuit will
blink, and no audible alerts will be present.
2. During circuit selection: The LED screen will indicate
the type of fault. The corresponding circuit LED and
alert indicator will flash, and the tester will provide an
audible alert (beep).
Crossed Circuits
The Alpha MUTT
®
indicates that two or more circuits are
back feeding or crossed. This can be a symptom of two
wires in the same harness wearing through their insulated
coating and connecting.
1. When a crossed circuit is identified, the LCD screen will
display "CROSS CIRCUIT". The circuit LED that should
not be powered and needs correcting will flash, and the
tester will provide an audible alert (beep).
Short/Overloaded Circuit
Short circuits or overloads can occur when a positive/hot
wire touches ground or the load on the circuit exceeds the
allowable current or amperage draw (factory default 21
amps). A short or overload can also be a result of faulty
lights or poor connections.
1. If a short or overloaded circuit is suspected, the Alpha
MUTT
®
will instantly suspend power for 3 seconds
and enter Pulsar
®
mode until the short is removed.
2. The LCD screen will indicate the type of fault. The
corresponding circuit LED and alert indicator will flash,
and the tester will provide an audible alert (beep).
3. During Pulsar
®
mode, the Alpha MUTT
®
enters a 3-second countdown sequence. When the
countdown completes, the tester will attempt to restore power to the circuit. If a short is still present,
steps 1-3 will automatically repeat.
NOTE: Open Circuit indicator will only illuminate during circuit selection.
NOTE: In some cases, a crossed circuit may be a normal function of advanced diagnostic testing,
such as with certain ABS systems.
NOTE: Pulsar
®
mode can be a useful troubleshooting tool for finding dead and intermittent shorts.
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