قبل فحص المركبة، تحقق من رقم اللوحة وحزام الأمان.

Because Arabic often uses قبل + a verbal noun to express before doing something in a compact, formal way.

Here, فحص is a verbal noun meaning inspection / examining. So:

• قبل فحص المركبة = literally before the inspection of the vehicle
• natural English meaning = before inspecting the vehicle

This style is very common in instructions, manuals, and formal writing.

It is a noun, specifically a verbal noun (maṣdar).

The root idea is to inspect / examine, and فحص names that action as a thing:

• فحص = inspection / examining

So this phrase is not saying before he inspected or before you inspect. It is using the action as a noun after قبل.

Because فحص المركبة is an iḍāfa construction, often called a possessive or X of Y structure.

In an iḍāfa:

• the first noun usually does not take الـ
• the second noun determines definiteness

So:

• فحص المركبة = inspection of the vehicle

Not:

• الفحص المركبة ✗

The first noun, فحص, stays without الـ because it is the first part of the iḍāfa.

المركبة means vehicle, and it is broader and more formal than السيارة (car).

So:

• السيارة = car
• المركبة = vehicle

In official instructions, safety notices, and regulations, Arabic often prefers المركبة because it can refer to any vehicle, not just a car.

تحقق is an imperative verb, meaning it is a command: check / make sure / verify.

More specifically, it is the masculine singular command form. The implied subject is:

• أنتَ = you (masculine singular)

So تحقق means:

• Check
• Make sure
• Verify

If the command were addressed to other people, the form would change.

Because in this meaning, the verb is used as تحقق من, which means:

• make sure of
• verify
• check

So the preposition من is part of how this verb works in this context.

Examples:

• تحقق من المعلومات = verify the information
• تحقق من الباب = check the door

Without من, تحقق can have other meanings depending on context, such as was realized, came true, or was achieved. So من is important here.

رقم اللوحة is another iḍāfa construction.

It breaks down as:

• رقم = number
• اللوحة = the plate

So literally it is:

• the number of the plate

In natural English, that becomes:

• the plate number
• or more specifically the license plate number

This is a very common Arabic structure: two nouns placed together, where English often uses of or reverses the order.

Because حزام الأمان is the standard Arabic expression for seat belt.

It is also an iḍāfa:

• حزام = belt
• الأمان = safety

So literally:

• safety belt

In actual usage, this is the normal Arabic term for seat belt. Many Arabic expressions are built this way, where the literal wording and the natural English wording are not identical.

Because one preposition can govern two coordinated nouns in Arabic, just as in English.

So:

• تحقق من رقم اللوحة وحزام الأمان

means:

• check the plate number and the seat belt

The من applies to both items. Arabic does not need to repeat it:

• من رقم اللوحة وحزام الأمان

That is perfectly normal.

With full vowel endings, it would be:

قَبْلَ فَحْصِ الْمَرْكَبَةِ، تَحَقَّقْ مِنْ رَقْمِ اللَّوْحَةِ وَحِزَامِ الْأَمَانِ.

A quick breakdown:

• قبلَ: accusative as an adverbial expression of time (before)
• فحصِ: genitive, because it is linked to قبل in an iḍāfa
• المركبةِ: genitive, because it is the second noun in فحص المركبة
• تحققْ: imperative, ending in sukun
• من: preposition
• رقمِ: genitive after من
• اللوحةِ: genitive as second noun in رقم اللوحة
• حزامِ: genitive too, because it is coordinated with رقم
• الأمانِ: genitive as second noun in حزام الأمان

In normal everyday Arabic writing, these endings are usually not written.

Yes. A more explicit version would be:

قبل أن تفحص المركبة، تحقق من رقم اللوحة وحزام الأمان.

That means the same thing: Before you inspect the vehicle, check the plate number and the seat belt.

The difference is mostly style:

• قبل فحص المركبة = more compact, formal, instruction-like
• قبل أن تفحص المركبة = more explicit, more like a full clause

Both are correct, but the original sentence sounds very natural for formal instructions.