24
Probe the suspected ground wire or contact with the probe tip.
Observe the green LED. Depress the power switch forward then release.
If the green LED went out and the red LED came on, a beep will
sound, this is not a true ground.If the circuit breaker tripped, this circuit
is more than likely a good ground. Keep in mind that high current
components such as starter motors will also trip the circuit breaker.
In most cases a short circuit will appear by a fuse or a fusible link
blowing or an electrical protection device tripping (i.e., a circuit
breaker). This is the best place to begin the search.
The Red/Green Polarity LED lights up when the probe tip voltage
matches the battery voltage within ±0.4 volts. It is added information
that could be valuable to the technician.
Remove the blown fuse from the fuse box.
Follow the wire as far as you can along the wiring harness.
Here is an example for this application.
If you are following a short in the brake light circuit, you may know
that the wire must pass through the wiring harness at the door sill.
Locate the color-coded wire in the harness and expose it.
Probe through the insulation with the probe tip, and depress the
power switch forward to activate and energize the wire.
If the circuit breaker tripped, you have verified the shorted wire.
Cut the wire and energize each end with the probe tip. The wire end
which trips the circuit breaker again is the shorted circuit and it will
lead you to the shorted area.
Follow the wire in the shorted direction and repeat this process until
the short is located.
Use the probe tip to activate and energize each of the fuse contacts.
The contact which trips the circuit breaker is the shorted circuit.
Take note of this wire’s identification code or color.
3.8 Checking for Bad Ground Contacts
3.9 Following & Locating Short Circuits
3.10 Red/Green Polarity LED
