Si el freno vuelve a sonar raro, mi madre no querrá conducir de noche.

This is the normal pattern for a real future condition in Spanish:

• Si + present indicative, then
• future (or another main-clause tense) in the result

So:

• Si el freno vuelve a sonar raro = If the brake sounds strange again
• mi madre no querrá conducir de noche = my mother won’t want to drive at night

A key point: in standard Spanish, you normally do not use the future tense directly after si in this kind of sentence.

So Spanish prefers:

• Si vuelve, no querrá...

not:

• Si volverá, no querrá... ❌

This is similar to English If it happens, she won’t want...

Volver a + infinitive means to do something again.

So:

• volver a sonar = to sound again
• vuelve a sonar raro = it sounds strange again / it starts sounding strange again

It is a very common structure in Spanish:

• Volví a leer el mensaje. = I read the message again.
• ¿Vas a volver a intentarlo? = Are you going to try again?

Here, vuelve a tells us that the brake had already made a strange noise before.

Because sonar often works like a linking verb here, similar to to sound in English.

In English, we say:

• That sounds strange
• not That sounds strangely in this meaning

Spanish works the same way:

• suena raro = it sounds strange
• not suena raramente for this idea

So raro is an adjective, describing how the brake sounds.

Other similar examples:

• Suena bien. = It sounds good.
• Suena mal. = It sounds bad.
• Eso suena extraño. = That sounds strange.

Raro agrees with the noun it describes, which here is el freno.

• el freno is masculine singular
• so the adjective is raro

If the subject changed, the adjective would change too:

• el freno suena raro = masculine singular
• la rueda suena rara = feminine singular
• los frenos suenan raros = masculine plural
• las ruedas suenan raras = feminine plural

So the ending of raro matches freno.

Yes, English often uses the brakes as a general system, but Spanish can use el freno in the singular to refer to:

• a brake,
• the brake mechanism,
• or even the braking system in a general way, depending on context.

So el freno is completely natural.

You could also hear los frenos in other contexts:

• Los frenos hacen ruido. = The brakes make noise.

The singular here may suggest one specific brake, or just treat the brake as one unit.

Querrá is the future tense of querer.

• quiere = wants
• querrá = will want
• querría = would want

In this sentence, the speaker is talking about what will happen if the brake makes that strange noise again, so the future fits best:

• mi madre no querrá conducir de noche = my mother won’t want to drive at night

Why not querría?

Because querría often sounds more like:

• would want in a hypothetical sense
• or a polite form

Here the sentence is not presenting a distant hypothetical situation; it is a likely future consequence. So querrá is the natural choice.

Also note that querer has an irregular future stem:

• infinitive: querer
• future stem: querr-
• future: querrá

Yes, it could be omitted.

Spanish often leaves out subject pronouns and even explicit subjects when the meaning is clear from the verb ending and context.

So both are possible:

• Si el freno vuelve a sonar raro, mi madre no querrá conducir de noche.
• Si el freno vuelve a sonar raro, no querrá conducir de noche.

Including mi madre can help:

• make the subject extra clear
• add emphasis
• avoid ambiguity if more than one person has been mentioned

So it is not required, but it is perfectly natural.

Both can relate to night, but they are not used in exactly the same way.

In this sentence, de noche means at night / during the night in a general sense:

• conducir de noche = to drive at night

It is a common expression for activities done during nighttime in general.

Por la noche often means in the evening / at night, and can sound a bit more like a time period when something happens.

Compare:

• No me gusta conducir de noche. = I don’t like driving at night.
• Llegaremos por la noche. = We’ll arrive at night / in the evening.

So here, de noche is very natural because it describes the general circumstance of driving.

Because de noche is a fixed adverbial expression.

Spanish often uses de + noun without an article in set phrases that describe manner, time, or condition:

• de noche = at night
• de día = during the day / by day
• de pie = standing
• de memoria = from memory

So conducir de noche is just the standard way to say to drive at night.

If you used por la noche, then the article appears because that is a different structure.

It can do both, depending on context.

With a literal subject like el freno, it is usually about the actual sound:

• El freno suena raro. = The brake sounds strange.

But with an idea, explanation, or statement, sonar raro can also mean to seem odd / suspicious / off:

• Eso suena raro. = That sounds strange.
• Tu excusa suena rara. = Your excuse sounds odd.

So sonar raro can be literal or figurative. In your sentence, it is clearly the literal sound of the brake.

Querrá is pronounced roughly keh-RRAH, with the stress on the last syllable.

The written accent mark on á shows that the stress falls there:

• que-rrá

Without the accent, Spanish stress rules would make you expect a different pronunciation.

This accent is normal in many future forms:

• tendrá
• podrá
• saldrá
• querrá

So the accent mark is there to show the correct stress, not to change the basic meaning.