Electrical Accessory Systems

The primary purpose of electrical accessories on a vehicle is to:

Control engine timing and fuel injection Provide driver and passenger comfort, convenience and safety functions Increase alternator output at idle Reduce the need for mechanical components

A typical power window system uses which type of motor?

Small DC permanent magnet motor with gear reduction Three-phase AC induction motor Hydraulic motor controlled by the PCM Stepper motor controlled by the alternator

An inoperative power window on one door ONLY is most likely caused by:

Main circuit breaker failure Open circuit in that door's switch, wiring, or motor Faulty alternator field circuit Defective ignition coil

On most vehicles, daytime running lamps (DRL) are required to:

Provide full high-beam intensity at night Increase vehicle visibility during daytime operation Replace tail lamps at night Reduce battery charging time

A headlamp with poor brightness on both high and low beam, while other lamps are normal, may indicate:

Blown headlamp fuse High resistance in the headlamp ground circuit Shorted alternator rectifier Weak ignition spark

Fog lamps are designed to:

Provide long-distance high intensity lighting Produce a wide, low beam to reduce glare in fog and snow Replace headlamps under all conditions Illuminate the engine compartment

A wiper motor 'park' circuit is used so that:

Blades stop wherever the switch is turned off Blades always stop at the bottom of the windshield Wipers operate only at high speed Washer pump is disabled

The intermittent wiper function operates by:

Changing motor direction between sweeps Cycling power to the wiper motor at set time intervals Changing wiper blade pressure Varying washer fluid pressure

A rear window defogger grid usually consists of:

Heated coolant tubes in the glass Fine resistive conductors bonded to or in the glass Vacuum lines routed through the tailgate Photocells for automatic headlamp control

A blown fuse for the rear defogger circuit most likely indicates:

Open grid wire Short to ground in the wiring or switch, or excessive current draw Normal operation of the timer Weak alternator

Many modern vehicles use body control modules (BCMs) to:

Directly control fuel injection only Manage accessory functions such as power windows, locks and lighting Control piston movement Regulate battery electrolyte

An electrical accessory circuit that stays on with the key removed may indicate a fault in the:

Accessory relay or BCM output Starter solenoid Alternator stator winding Ignition coil primary circuit

When troubleshooting an inoperative horn, the FIRST check should usually be:

Remove the steering wheel Check the horn fuse and relay operation Replace the airbag module Adjust the alternator belt tension

A heater blower motor that operates only on the highest speed usually has a fault in the:

Blower relay contacts Resistor block that controls lower speeds Ignition switch ACC contacts Heater core itself

Power door lock actuators are typically:

Vacuum-operated only Small electric motors or solenoids that move lock linkages Hydraulic cylinders supplied by power steering Controlled directly by the alternator regulator

Keyless entry systems use which type of technology between the key fob and vehicle?

Mechanical cable connection Radio frequency (RF) signals and coded messages Vacuum hoses Direct wired connection through the ignition key

A customer complaint of 'battery dead after vehicle left parked for several days' may be due to:

Normal operation of the horn circuit Excessive parasitic draw from an accessory module staying awake Starter field coil short Under-inflated tires

Most electric seat systems include which type of protection device?

Fuel pump inertia switch Circuit breaker or self-resetting fuse Ignition resistor wire Glow plug timer

When replacing an electrical accessory switch, the parts technician should match:

Colour of the knob only Connector style, pin count, mounting style and function as listed in the ILM and catalogue Any switch that fits the panel opening Only the physical size of the switch body

Courtesy lamps are usually controlled by:

Oil pressure switch Door jamb switches and body control module logic Alternator field circuit Starter relay

A brake lamp that does not illuminate when the pedal is pressed may be caused by:

Open brake switch, blown fuse, faulty wiring or burned out bulbs Low engine coolant level Shorted alternator rotor Worn brake pads only

Trailer lighting circuits often require:

Heavier gauge wiring and separate fusing or relays Direct connection to ignition coil terminals Using the battery negative as a power feed Removal of the vehicle's original lamps

An accessory relay is used to:

Decrease current capacity of the circuit Allow a low current control circuit to switch higher current loads safely Prevent operation of accessories with the key on Control engine compression

Heated seats use which type of device to generate heat?

Small light bulbs Resistive heating elements in the seat cushion and back Hydraulic fluid heaters Exhaust gas recirculation valves

When diagnosing a power mirror that moves in some directions but not others, a likely cause is:

Blown main fuse Fault in the mirror switch or internal directional motor circuits Open alternator stator Weak battery cell

An automatic headlamp system uses a light sensor to:

Measure battery voltage Determine ambient light level and switch headlamps on or off Control alternator output Operate the starter relay

A rear wiper system that works continuously even with the switch OFF may have a fault in the:

Wiper blade Control switch, relay contacts stuck closed, or BCM output Alternator pulley Engine oil pressure switch

When replacing bulbs with LED units, the technician must ensure:

Voltage and socket type are correct and any required resistors or modules are used Any LED bulb will fit any socket LEDs may be installed in place of fuses No consideration of polarity is necessary

Window lockout switches are installed so that:

Rear passengers can always operate windows Driver can disable window operation from other switches for safety Windows cannot be closed fully Sunroof is disabled permanently

A vehicle information centre that displays warnings in the instrument cluster is usually driven by:

Mechanical cables Data messages over vehicle networks from control modules Vacuum hoses from intake manifold Alternator AC ripple

An accessory circuit that repeatedly blows fuses immediately when turned on most likely has:

Open circuit Short to ground or internal short in the load Correct operation Weak relay coil

When selecting relays or flashers, the parts technician should consider:

Terminal configuration, amp rating and control type as specified in ILM and catalogue Any relay will work in any socket Colour of the relay case only Voltage rating can be ignored