Short, Open, Loads, FInding Short Circuits

What are the two types of short circuits?

A short to power and a short to ground.

What happens when there is a short to power within a component?

The component will not operate properly or may not operate at all.

How can a short in a component be diagnosed?

By checking the resistance of the component with an ohmmeter.

What usually occurs when there is a short to power between circuits?

Components operate unintentionally.

What causes a short to ground to usually blow a fuse?

The short creates an immediate excessive current flow, resulting in a blown fuse.

What happens if the short to ground is before a ground-side switch?

The fuse will not blow, but the component will not turn off.

What tool can be used to detect a short to ground?

A short finder.

How does a short finder work?

It creates a pulsing magnetic field in the circuit, and the meter indicates when it passes a short.

What is an intermittent short?

A condition where a fuse blows only during a transient period of high current.

What can cause a transient short?

Faulty insulation or moisture entering the wiring.

What could cause a momentary overload in a circuit?

A defective motor unit during startup.

What happens if a motor mechanism is jammed?

The protection device will intervene to prevent damage.

What could indicate a transient condition in circuits with multiple loads?

A blown fuse that seems to reset and works again later.

What is an open circuit?

A circuit where current flow is interrupted due to a break in the conductor.

What can create an open circuit?

A defective switch, relay, or wire.

How do you restore a circuit with an open?

Find and repair the break in the circuit.

What is a load device in a circuit?

The unit that performs the work, like lights or motors.

What should occur when proper voltage reaches the load device?

The load should operate correctly.

What should be checked to diagnose voltage drop across a load device?

Using a voltmeter to check for power and proper voltage drops.

What do all circuits require?

A ground.

How are some loads grounded in vehicles?

Internally to the frame or externally wired to ground.

What should be done before applying energy to a replaced part?

Reconnect the ground wire.

What can worn or burned wiring insulation cause?

Short circuits.

How can a blown fuse be diagnosed if no short is evident?

Replace the fuse and see if it holds or check for intermittent shorts.

What is a unique characteristic of motors when starting?

They require more current to start than to keep running.

What should you do if only one load on a circuit is working after a fuse replacement?

Check the circuit diagram for dual connections.

What instrument is helpful in diagnosing electrical faults?

A voltmeter or circuit probe.

Why might moisture enter wires and create a short?

Through a worn spot in the insulation.

What is a tell-tale sign of a defect in the motor mechanism?

The protection device blowing a fuse when the driver activates it.

What precaution should be taken when replacing components like wiper motors?

Ensure that the ground connection is restored.

How are components within a circuit expected to interact?

They should operate correctly without shorts or interruptions.

What is one common cause of signaling a short circuit?

A damaged or defective wiring harness.

Why is tracing wiring diagrams important?

To accurately find and repair shorts or opens in circuits.

Where might you find greater usage of external ground methods?

In vehicles with larger amounts of plastic and fiberglass panels.