SVP Auto Electrician flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Lockout tagout purpose

Lockout/tagout isolates hazardous energy before service and prevents accidental re-energization; verify zero energy at the point of work before touching conductors or moving parts.

Lead-acid hydrogen hazard

Charging lead-acid batteries releases hydrogen gas, which is flammable and explosive; keep flames, sparks, and smoking away and ventilate the charging area.

Sulfuric acid first aid

Battery electrolyte is sulfuric acid; for skin or eye contact flush immediately with copious water for at least 15 minutes and seek medical attention.

High-voltage orange cable

In hybrid and electric vehicles, orange cable identifies high-voltage circuits; do not cut, probe, or disconnect them without manufacturer procedure and rated PPE.

Multimeter CAT rating

A multimeter's CAT rating states its safe use against transient overvoltage; automotive work generally requires at least CAT III and a fused current input.

Voltage measurement connection

Voltage is measured in parallel across the component or circuit, with the meter's high-impedance input; never connect a meter in series for voltage or across a live circuit for resistance.

Current measurement connection

Current is measured in series with the circuit, so the meter becomes part of the current path; use the correct fused input and never exceed the meter's current rating.

Torque wrench calibration

A torque wrench should be checked periodically and used within its specified range; torque fasteners to the manufacturer's value and sequence, and store the wrench at its lowest setting.

Ohm's law formula

Ohm's law states that voltage equals current multiplied by resistance, V = I × R; it applies to resistive circuits and is used to calculate unknown voltage, current, or resistance.

Series circuit current

In a series circuit, the same current flows through every component, total resistance is the sum of individual resistances, and the supply voltage divides in proportion to resistance.

Parallel circuit voltage

In a parallel circuit, each branch has the same voltage, total resistance is less than the smallest branch resistance, and branch currents divide inversely with branch resistance.

Silicon diode forward drop

A forward-biased silicon diode conducts with a voltage drop of about 0.7 V; a germanium diode drops about 0.3 V, and a reverse-biased diode blocks current.

12V battery state of charge

For a rested 12 V lead-acid battery, about 12.6 V indicates full charge, 12.2 V about half charge, and 11.8 V or lower indicates deep discharge; surface charge must be removed before testing.

Alternator charging voltage

A healthy 12 V alternator typically regulates charging voltage to about 13.5–14.5 V at normal temperature; excessively high voltage can overcharge and damage the battery.

Cranking voltage test

During a cranking test at about 20 °C, battery voltage should generally stay above 9.6 V; a lower reading suggests a weak battery, poor connections, or excessive starter current draw.

Parasitic draw measurement

Parasitic draw is measured with a clamp meter around the negative battery cable after modules sleep; a typical specification is below about 50 mA, though manufacturer values vary.

Halogen bulb handling

Halogen bulb glass must not be touched with bare fingers because oils create hot spots that shorten bulb life; handle by the base or with clean gloves.

LED polarity

An LED is polarity-sensitive and lights only when its anode is positive relative to its cathode; reversing polarity prevents conduction and may damage the LED in some circuits.

Turn signal flasher LED

LED turn signals draw less current than incandescent bulbs, so a thermal flasher may hyperflash; use an LED-compatible flasher or the correct load resistor.

Fuse protects wiring

A fuse is selected to protect the wiring, not the load; its rating must not exceed the wire's current capacity, and a larger fuse must never replace a blowing fuse.

Relay terminal numbers

Common automotive relay terminals are 30 for battery feed, 87 for load output, 85 and 86 for the coil, and 87a for the normally closed contact.

Crimp terminal pull test

After crimping, perform a pull test to confirm mechanical strength; a good crimp holds the conductor without damage, and solder should not be relied on for vibration resistance.

Voltage drop limit

Voltage drop testing under operating load finds resistance; generally a connection should drop less than about 0.1 V and a cable less than about 0.3 V, though specifications vary.

Power window reversal

Many power window motors reverse direction when supply polarity is reversed; module-controlled windows may use relays or solid-state drivers and require initialization after repair.

Wiper park switch

The wiper park switch keeps the motor powered after the switch is turned off until the blades reach the park position, then opens the circuit to stop the motor.

Immobilizer no-start

An immobilizer prevents starting when the key transponder is not recognized; a mismatch between key, immobilizer, and engine ECU can cause cranking but no start.

CAN bus termination

A CAN bus uses a twisted pair with two 120-ohm terminating resistors; measured across the bus with power off, resistance should be about 60 ohms.

Five-volt reference

Many ECU sensors receive a regulated 5 V reference and return a signal voltage; check reference and ground before condemning a sensor or ECU.

Hall effect sensor output

A Hall effect sensor produces a digital square-wave signal as a toothed target passes it; it needs a supply, ground, and signal circuit and can be tested with a scope.

DTC freeze frame

Freeze frame data records operating conditions when a diagnostic trouble code set, such as speed, load, and temperature, helping reproduce the fault and avoid parts replacement by guesswork.

Wiggle test harness

A wiggle test flexes harness sections and connectors while monitoring scan data or a meter; a changing reading indicates an intermittent connection or damaged wire.

Repair verification

After repair, clear codes, operate the system under the original conditions, and confirm normal data and function; verify no code returns and perform a road test where appropriate.