Starting Systems Questions and Answers

Answer: C

Both ends of the pull-in winding reach the same potential once the main contacts close, so no current flows through it. That saves a great deal of current during cranking. The hold-on winding alone keeps the plunger in place. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Framing the question as which quantity the change acts upon makes the answer follow without calculation.

Answer: D

With the pull-in winding shorted out and no hold-on winding, the plunger falls back, which reopens the contacts and the cycle repeats. The result is rapid chattering. A flat battery produces the same noise for a different reason. Most errors here come from carrying across a result from a neighbouring case where it does not hold. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. A limit that survives making every external component ideal is an intrinsic one, and worth knowing for that reason.

Answer: A

The solenoid engages on the small current it needs but the battery cannot supply the hundreds of amps the motor demands. Worn brushes give the same symptom, which makes the last option a genuine alternative that voltage drop testing distinguishes. Naming what changes and what stays the same is the reliable route through questions of this shape. The order in which the effects act is what decides the outcome, so it is worth establishing first. The shared properties explain why these belong to one family, and the differences explain why more than one exists.

Answer: B

Measuring the drop from battery positive to starter terminal and from starter body to battery negative while cranking isolates the fault. Ohmmeters cannot resolve milliohms. A low battery voltage during cranking is ambiguous. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb. Checking which component actually carries the load settles most questions of this kind at once. Most errors here come from carrying a result across from a neighbouring case where it does not hold.

Answer: C

Manufacturers typically allow around half a volt on the insulated side and less on the earth. Zero is impossible with any real conductor. A whole volt at two hundred amps means two hundred watts being wasted as heat. A symptom that appears under one condition and not another is what narrows the diagnosis quickly. The shared behaviour explains why these belong together and the differences explain why both exist. Checking the units of each quantity catches a wrong formula before the arithmetic begins.

Answer: D

A heavy braided strap between the engine and the body carries the starter return, and a corroded one produces slow cranking. The mounting bolts do carry current, which makes the second option part of the real path rather than an invention. The order in which the effects act is what decides the outcome, so it is worth establishing first. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: A

Resistance in the earth wastes voltage as heat and starves the motor, so cranking is slow and the strap gets warm. A completely broken strap does give no cranking, which makes the second option the extreme case of the same fault. Checking which component actually carries the load settles most questions of this kind at once. Reading the definition literally, rather than recalling a summary, avoids the usual confusion. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: B

Starter current will find any path to the body, and cables and pipes have been melted by it. It is a real fire risk. The exhaust is a genuine partial path on some vehicles despite the rubber mountings. Tracing the requirement back to the physical constraint that produces it makes the answer follow. Most errors here come from carrying across a result from a neighbouring case where it does not hold. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision.

Answer: C

Permanent magnets replace the field coils and a reduction gear lets a small fast motor produce the torque needed. The result is around half the weight of an older starter. Higher voltage genuinely is used on commercial vehicles for the same reason. The shared behaviour explains why these belong together and the differences explain why both exist. Naming what changes and what stays the same is the reliable route through questions of this shape. Framing the question as which quantity the change acts upon makes the answer follow without calculation.

Answer: D

A small pinion driving a large ring gear gives roughly fifteen to one, so the motor spins around three thousand revolutions per minute to crank at two hundred. Additional internal reduction raises the total further on geared starters. Naming the cost of a choice alongside its benefit is what turns a fact into a design decision. Working the distinction through on a single concrete case fixes it more firmly than any rule of thumb.