CDX Chapter 30 (meter usage and circuit diagnosis)

The way in which test probes are connected to a circuit.

Probing technique

A condition in which the current flows along an unintended path

Short circuit

_________________ ________________ can occur anywhere in the circuit and can be difficult to locate, especially if it is intermittent.

Short circuits

A condition where power from one circuit leaks into another circuit

Short to power

________________ _______________ are used to connect the DVOM to or into the circuit being tested and come in pairs: one red and one black

Test leads

What setting is often used to measure vehicle battery voltage while the engine is cranking or the battery is charging?

The min/max setting

open circuit

a circuit that has a break that prevents the flow of current

All of the following are examples of common types of DVOM probes EXCEPT: ground probes, alligator clips, fine pin probes, insulation piercing probes.

Ground probes

Fault conditions in a circuit where the circuit is unintentionally contacting a grounded component or wire. This may result in a short, in the case of a power wire, or it could cause a circuit to stay line in the case of a switched ground circuit.

Grounds

A term that describes a circuit or components with more resistance than designed.

High resistance

A setting on a DVOM to store the present reading.

Hold function

When the ___________ function is activated, the display will hold the value on the display until the function or DVOM is turned off.

Hold function

Current flow is _________________ proportional to resistance

Inversely

________________ __________________ are used to extend connections to allow circuit readings or tests to be undertaken with a DVOM, an oscilloscope, current clamps on fuses, relays, connector plugs on components.

Jumper leads

A circuit that has a break that prevents current from flowing.

Open circuit

The sum of the current flow in each branch is equal to the total _________________ circuit current flow.

?

short to power

A condition in which current flows from one circuit into another

Min/max setting

A setting on a DVOM to display the min and max readings

high resistance

A term that describes a circuit or components with more resistance than defined

DVOM (digital volt-ohmmeter)

A test instrument with a digital display for measuring voltage, resistance and current

A ---------- must be connected in series within a circuit.

Ammeter

A digital volt-ohmmeter for,three phase fixed equipment and single phase commercial lighting would have what type of rating?

CAT III

_________________-________________ occurs when the probe is pushed in from the back of a connector to make a connection.

Back probing

What is the same in all parts of a properly working series circuit? Voltage, current, resistance or all of the above

Current

The _______________ ____________ fastens around the conductor and measures the strength of the magnetic field produced from current flowing through the conductor.

Current clamp

After back probing always reinsulate the hole that the probe makes with room temperature vulcanizing silicone to prevent corrosion. T/F?

False. Room temperature vulcanizing silicone attracts moisture as it cures, potentially causing corrosion.

Unwanted voltage _______________ in vehicle circuits can cause real problems and faults.

Drop

The red lead is the positive lead and the black lead is the negative lead. T/F ?

False

5208 MV is the same as 5208 millivolts. It could also be called 52.08 volts. T/F?

False. (5208 x .001 = 5.208)

A series-parallel circuit occurs when wanted resistance shows up in series with a parallel circuit. T/F ?

False. Occurs when UNWANTED resistance shows up.

Probing technique

The way in which test probes are connected to a circuit

Hybrid vehicles typically require meters and test leads rated as CAT III or CAT IV. T/F ?

True

If the resistance and voltage of a circuit are known, then the theoretical current can be calculated using Ohm's law.

True

Parallel circuits are commonly used in the vehicles electrical system, especially for lights. T/F?

True

The DVOM reading of OL means overload and indicates the voltage being read is higher than the maximum allowed for the range. T/F ?

True

To accurately measure the resistance of a component you should remove or isolate the component from the circuit. T/F ?

True

Voltage drops can be measured across components , connectors or cables, but current has to be flowing to get an accurate measurement. T/F?

True

The red lead for the DVOM is labeled with what symbol?

V/(omega symbol)

A basic digital ___________________-_______________ cam measure alternating current (AC) and direct current (DC) voltage, amperage and resistance.

Volt-ohmmeter

As the position of the wiper of a potentiometer is changed, so is the ------------- to a load connected to,the potentiometer.

Voltage and current flow

The sum of all the --------- in a series circuit equals the supply voltage.

Voltage drops

A digital volt-ohmmeter is used to measure

Voltage, resistance and amperage