Free SVP Auto Electrician Exam Flashcards

Shock risk is low at 12 volts, but insulation stops a tool, ring or watch bridging battery positive to the body earth. That short can weld metal and burn skin within seconds. The hazard is arc and burn, not electrocution.

It secures the isolated energy source, normally the disconnected battery or a main disconnect, so nobody can reconnect it while you work. The tag names who applied it. Only the person who fitted the lock removes it.

Charging releases hydrogen, which ignites from a spark or flame at low concentrations. Ventilate the bay, keep sparks away, and switch the charger off before moving clamps. A blast sprays sulphuric acid as well as case fragments.

Flush with clean water continuously for at least fifteen minutes, holding the eyelids open, then get medical help. Never try to neutralise acid in the eye. Goggles are the real control; flushing only limits the damage.

Wear the respirator for soldering fume, drilling dust and work around large electrical equipment. A light-duty mask suits general installation dust only. Solder fume and fine particulate pass straight through a simple mask.

Water conducts, so the jet can carry current back to the operator and spread the fire. Use a carbon dioxide or dry powder extinguisher rated for electrical equipment, and isolate the supply as soon as it is safe.

Wait for the system reserve capacitor to discharge for the manufacturer's stated time before touching squib connectors. The reserve can still fire the module after the battery is off. Never probe airbag circuits with a test lamp.

It marks voltage class B wiring, which ISO 6469-3 defines as above 60 volts DC or above 30 volts AC. Only technicians trained and equipped for high voltage may disconnect it. Ordinary 12-volt practice does not apply.

Static from your body can puncture semiconductor junctions inside the module with no visible sign, so it fails intermittently or later. Ground the strap and leave the module in its conductive bag until the moment of fitting.

A correctly crimped terminal. Solder wicks along the strands and creates a rigid point where the copper work-hardens and snaps under vibration. If soldering is unavoidable, support the joint and seal it with adhesive-lined heat shrink.

The inner glue melts and seals the joint against moisture and salt, so the copper cannot corrode under the sleeve. Plain heat shrink only covers the joint. Under-bonnet and underbody repairs need the sealed type.

The fuse protects the wire, not the load. A larger fuse lets the harness carry more current than its insulation can survive, so the wire becomes the fuse and can start a fire. Find the fault instead.

The thinner conductor has higher resistance, so it drops voltage, runs hot and can melt before the fuse opens. Match or exceed the original cross-section, and keep the repaired section as short as the routing allows.

Strain relief and sealing. Stagger multiple splices along the loom so it stays flexible, insulate each one separately, then re-wrap. Splices bunched at one point create a stiff lump that chafes and cracks nearby insulation.

The wide plastic blade spreads the load across the clip, so it does not mark the panel or cut the vapour barrier. A screwdriver concentrates force, breaks clips and can pierce wiring hidden behind the trim.

It identifies the exact plug and cavity to probe, so you test the right terminal instead of guessing. Pin numbering is drawn from a stated side, terminal face or wire side, so read the diagram note before counting cavities.

Back-probing reaches the terminal from behind the seal without breaking insulation. A pierced wire admits moisture and corrodes months later, producing a new intermittent fault that will be blamed on your repair.

Routing keeps the harness away from heat, sharp edges and moving parts. An unsecured repair rubs through within months and shorts to the body. Restore the original clips and standoffs after any harness work.

It lifts oxide and oil films while leaving the terminal plating intact, then evaporates without residue. Abrasives strip the tin or gold plating, so the joint corrodes faster than before. Apply dielectric grease only where specified.

Under DIN 72552, 30 is the battery feed to the contacts, 85 and 86 are the coil (85 usually to earth), 87 is the normally open contact that closes when the coil is energised, and 87a is the normally closed contact. Swapping 87 and 87a leaves the load permanently on or permanently off.

Use the clamp for high current such as starter or alternator output, where breaking the circuit is unsafe and the meter fuse would blow. The clamp reads the magnetic field around the conductor, so the circuit stays intact.

The waveform over time: dropouts, glitches, rise time and noise. A multimeter averages, so a briefly missing pulse still reads a plausible voltage. Intermittent sensor faults are found on the trace, not in the number.

It draws far more current than a module output can supply and can destroy the driver transistor inside the module. Use a high-impedance digital multimeter or an LED logic probe on electronic circuits.

You measure the voltage lost across a cable, joint or switch while normal current flows. Resistance only reveals itself under load, so an unloaded resistance check can pass on a connection that collapses when the motor runs.

A stored code names the circuit or condition the module rejected at some earlier moment. Live data shows what the sensors report right now. Codes point at an area; data confirms whether the fault is present.

It is a snapshot of operating conditions recorded when a fault code set, such as speed, load and coolant temperature. It tells you how to reproduce the fault on a road test instead of guessing at conditions.

The current terminals connect through a low-value shunt. Leaving the leads in the volts socket while connecting in series puts a near short across the supply and blows the meter fuse or the circuit fuse.

It applies a small alternating signal and measures the plate response, estimating capacity and internal resistance without deeply discharging the battery. It still works on a partly discharged battery, unlike a carbon-pile load test.

Straight after charging or driving, the plates hold a surface charge that reads high and hides a weak battery. Rest the battery or apply a brief load first. Otherwise a failing battery passes the voltage check.

A hot battery needs a lower charging voltage, so a fixed setpoint overcharges it, drives off electrolyte and shortens life. Temperature-compensated charging reduces voltage as temperature rises. In Gulf conditions heat, not cold, ends most batteries.

Cold cranking amps describe the burst of current available for starting at low temperature. Reserve capacity describes how long the battery can run essential loads with the alternator dead. High cranking amps does not guarantee good reserve.

A flooded profile's equalisation and desulfation stages and loose voltage control push a sealed cell into sustained gassing. The gas escapes through the pressure valve and water cannot be replaced, so the cell dries out permanently. Use a charger with an AGM profile that holds voltage tightly and skips equalisation.

Output is only as good as the return. A corroded case-to-engine or engine-to-body strap adds voltage drop on the ground side, so the battery undercharges while the alternator itself tests fine. Test both sides of the loop.

Mechanical drag or an internal short: worn bushes, a rubbing armature or a seizing engine. Compare that with low draw plus slow cranking, which instead points to high resistance in the cables, connections or ground.

The control module varies alternator output with battery state, temperature and electrical load to save fuel, so voltage rises and falls by design. Judging it against a single fixed figure condemns good alternators. Compare against manufacturer strategy and scan data.

The pull-in winding draws heavy current to throw the pinion and close the main contacts; the hold-in winding then keeps them closed. If supply voltage collapses under load the hold-in lets go, the contacts open, voltage recovers and the cycle repeats. Chatter points to supply or connections, not the starter motor.

The reflector is shaped around a filament in a fixed position. An LED emitter sits differently, so light scatters instead of forming the designed beam and cut-off. Raw output rises while useful illumination falls and glare increases.

The switch becomes a low-current input while the module drives the lamp and can monitor its current for outage warnings. So a dead lamp circuit may be a module or network problem, with a perfectly good switch.

The module switches the supply on and off rapidly, and the ratio of on-time to cycle time sets the average brightness. A multimeter shows an average that matches no real setting, so use a scope or duty-cycle mode.

The module still measures the wrong current, usually because a lower-wattage or LED bulb was fitted, or because a corroded socket adds resistance. Confirm the specified bulb type first, then inspect the socket terminals.

The fault is in the door switch, its ground, or the wiring back to the master switch, because the motor and its feed are already proven. Control normally passes through the local switch, so test that leg.

The module must be loaded with the correct calibration and matched to the vehicle's immobiliser, options and learned values. A physically identical unit that is not configured may refuse to start the engine or run the wrong strategy.

Those sensors share one regulated reference supply from the module. A short anywhere on that rail pulls it down, so every sensor fed by it reports out of range at once. Unplug sensors one at a time.

A circuit code means the voltage sat outside electrical limits, such as open or shorted. A rationality code means the value was electrically legal but disagreed with other sensors. Rationality faults usually mean a drifting sensor, not broken wiring.

One module missing points to that module's power, ground or its own branch. Several missing at once points to the bus itself, a shorted pair or a failed terminating resistor. Record which modules still answer before removing parts.

The module has built up corrections around the old part's characteristics. Left in place, they push the new component off target and can recreate the original symptom. Reset or relearn adaptations using the manufacturer's procedure.

From a dedicated, correctly fused circuit added at the fuse box, never spliced into a safety or network circuit. Tapping airbag, braking or bus wiring adds load and noise where the module expects none and can set faults.

The power lead is unprotected between the battery post and the amplifier's own internal fuse. A fuse fitted within a short distance of the battery clears a chafed lead before it burns through the bulkhead.

It reads cabin, ambient and evaporator sensors, then commands blend and mode actuators and blower speed to hold a set temperature. A no-cooling complaint may therefore be a sensor input or actuator, not the refrigerant circuit.

On a modern vehicle the start request travels over the network and an immobiliser is already built in. A cut and spliced wire becomes a future fault and defeats the built-in diagnostics. Interface through the documented input.