Pinout of the ASh-4 lamp: a complete guide to connecting and repairing a car headlight

Lamp AS-4 is a classic element of automotive lighting that is still used in domestic cars (for example, VAZ 2101-2107, GAS, UAZ) and some Soviet-built foreign cars. Despite its apparent simplicity, incorrect pinouts or connections can lead to short circuits, blown fuses, or even a wiring fire. This article will help you understand contact diagram, connection nuances and typical mistakes when working with a lamp.

Many car owners are faced with a problem: the headlight does not light up, but the bulb is intact, or vice versa - when the low beam is turned on, the high beam is activated. Most often the reason for this is incorrect pinout of the base or oxidation of contacts. We will analyze in detail the standard circuit, modification options (for example, for LED analogues) and give step-by-step instructions for checking functionality.

If you have never worked with auto electricians, do not be alarmed: pinout AS-4 is intuitive, and a multimeter or even a test lamp is enough for diagnostics. The main thing is to maintain polarity and not confuse the contacts masses and nutrition.

What is an ASh-4 lamp and where is it used?

Lamp AS-4 (stands for "Automotive pin, 4 contacts") is a two-filament incandescent or halogen lamp designed for low and high beam in the headlights. She belongs to the type H4 according to the international classification, but has a unique base pinout, characteristic of Soviet and post-Soviet cars.

Main Applications:

• 🚗 Domestic cars: VAZ 2101–2107, GAZ 24/3102, UAZ 469/3151, Moskvich 2140/2141.
• 🔧 Soviet-built foreign cars: Fiat 124 (licensed VAZ 2101), some models Skoda and Renault 1970–1990s.
• 💡 Modernization: used in retro projects or as a budget replacement for old cars.

Structurally, the lamp has 4 contacts:

1. Weight (total minus).
2. Low beam power supply.
3. High beam power supply.
4. Additional contact (in some modifications - for dimensions or warning lamp).

Difference AS-4 from modern H4 - in the location of the pins and the distribution of stress. For example, in European lamps H4 The ground contact is often combined with the body, but here it is brought out separately.

Standard pinout of lamp contacts ASh-4

The key point when working with AS-4 — correctly identify contacts. Below is basic diagram for most cars:

Contact number	Purpose	Wire color (typical)	Voltage, V
1	Weight (total minus)	Black	0
2	Low beam	Yellow or white	+12
3	High beam	Blue or red	+12
4	Reserve/dimensions	Green (optional)	+12

⚠️ Attention: Wire colors may vary depending on the car model! For example, in GAZ-3102 low beam is often connected via a gray wire, and in UAZ - through orange. Always refer to your machine's wiring diagram.

To check the pinout without a diagram:

1. Disconnect the socket from the lamp.
2. Turn on the low beam and use a multimeter to find the voltage connection +12V (this is pin 2).
3. Check the high beam in the same way (pin 3).
4. Ground (contact 1) always “rings” to the car body.

Differences in pinouts in different cars

Although AS-4 standardized, car manufacturers sometimes made changes. Let's look at the most common options:

1. VAZ 2101–2107

• 🔌 Contact 1: ground (black wire).
• 🔌 Contact 2: low beam (yellow).
• 🔌 Contact 3: high beam (blue).
• 🔌 Contact 4: not used (or dimensions in some modifications).

2. GAZ 24/3102

• 🔌 Contact 1: ground (black).
• 🔌 Contact 2: low beam (gray).
• 🔌 Contact 3: high beam (red).
• 🔌 Contact 4: control lamp (green).

3. UAZ 469/3151

• 🔌 Contact 1: ground (black).
• 🔌 Contact 2: low beam (orange).
• 🔌 Contact 3: high beam (purple).
• 🔌 Contact 4: dimensions (white).

⚠️ Attention: In some UAZ and GAS Pin 4 can be used to illuminate the instrument panel. If after replacing the lamp the dimensions stop working, check this contact!

For accurate identification, use wiring diagram of your car. For example, in Moskviche 2140 The pinout may vary even depending on the year of manufacture.

Where can I find the wiring diagram?

Diagrams are usually found in the repair manual for your model. For domestic cars they can be downloaded from forums (for example, VAZClub or GAZman). For foreign cars, search by VIN code on sites like AutoData or Mitchell1.

Typical faults and their causes

If the lamp AS-4 does not work, the problem may lie not only in the light bulb itself. Here are the most common malfunctions and their possible causes:

• 💥 The lamp burns out:
  • Poor contact in the base (oxidation or burning).
  • Voltage surges in the on-board network (check the relay regulator).
  • Vibration (especially important for UAZ and Niva).
• 🔦 Low/high beams do not light up:
  • Broken wire or oxidation of contact 2 or 3.
  • Faulty light switch on the steering column.
  • Fuse problems (usually F7 or F8 in the block).
• ⚡ Short circuit:
  • The wires are shorted to ground (check the insulation).
  • Incorrect pinout when replacing lamp.
  • Moisture getting into the headlight (especially in VAZ 2106 with plastic headlights).

Critical error: Never connect the low beam contact (2) directly to the battery positive without a fuse! This may cause the wiring to catch fire.

Troubleshooting:

1. Check the lamp for functionality (connect directly to the battery).
2. Inspect the base for oxidation or burning.
3. Ring the wires from the block to the fuse box.
4. Make sure that ground (pin 1) is securely connected to the body.

How to properly connect an ASh-4 lamp: step-by-step instructions

If you are replacing a lamp or repairing a headlight, follow this algorithm:

1. Preparation:

• 🔧 Disable negative battery terminal.
• 🧤 Wear gloves (halogen lamps cannot be handled with bare hands!).
• 🔦 Remove the headlight protective cover (if equipped).

2. Removing the old lamp:

• 🔌 Disconnect the block with wires from the base.
• 🔄 Turn the lamp counterclockwise and remove it.
• 🧹 Clean the base from dirt and oxidation (use alcohol or WD-40).

3. Installing a new lamp:

• 💡 Insert the lamp into the base, aligning the pins with the grooves.
• 🔄 Turn clockwise until secure.
• 🔌 Connect the block, observing the pinout (see table above).

4. Check:

• 🔋 Connect the battery.
• 🔦 Turn on the low and high beams alternately.
• 🔍 Make sure there is no flickering or extraneous sounds (this is a sign of poor contact).

⚠️ Attention: If after replacement the lamp does not light, but the fuse is intact, check light relay (usually K6 in the fuse box). B VAZ 2107 it often fails.

Modernization: replacement of ASh-4 with an LED or xenon lamp

Many car owners want to improve their headlights by installing instead of the standard AS-4 LED or xenon lamps. However, there are several nuances here:

1. Light Emitting Diodes (LED):

• ✅ Pros: low power consumption, long service life, bright light.
• ❌ Cons: require correct polarity, may need an additional stabilization unit.

For AS-4 LED lamps with base are suitable H4, but you need:

• 🔌 Check the pinout (sometimes you need to swap + and –).
• 🔧 Install a cooling radiator (LEDs get hot!).
• 📏 Adjust the light beam (so as not to blind oncoming drivers).

2. Xenon lamps (HID):

• ✅ Pros: very bright light, durability.
• ❌ Cons: high price, requires ignition units, may have problems with the traffic police (if not certified).

For xenon you will need:

• 🔧 Install ignition units and voltage relays.
• 🔌 Connect power via fuse 20A.
• 📋 Legalize it at the traffic police (if the lamps are not standard).

⚠️ Attention: Installing xenon in headlights that are not designed for it can result in blinding oncoming drivers and a fine! Before replacing, check the headlight markings (there should be a letter D for xenon).

How to avoid problems with the traffic police?

If you install non-standard xenon, be sure to get tested by an accredited laboratory and make changes to the STS. The fine for illegal xenon is 3,000 rubles (Article 12.5 of the Administrative Code).

Frequent mistakes when working with the ASh-4 lamp

Even experienced car owners sometimes make mistakes that lead to breakdowns. Here are the most common:

• 🔌 Mixed up contacts: If you connect the low beam (pin 2) instead of the high beam (pin 3), the lamp will not work correctly and the filament may burn out.
• 🧤 Touching the halogen lamp bulb: oil from the fingers leads to local overheating and shortened service life.
• 🔧 Ignoring mass: poor contact on the “minus” (pin 1) leads to flickering of the light or complete failure.
• 💧 Moisture ingress: If you do not close the protective cover of the headlight, condensation will oxidize the contacts.
• ⚡ No fuse: Connecting the lamp directly to the battery without protection is fraught with fire.

How to avoid mistakes:

1. Always check the pinout up to lamp connections.
2. Use multimeter to check the voltage on the contacts.
3. After installation, adjust the headlights (especially if you replaced the lamp with an LED one).

Important: if after replacing the lamp the dimensions stop working, check pin 4. In some cars it is responsible for powering the dashboard backlight.

FAQ: answers to frequently asked questions

Is it possible to replace the ASh-4 with a regular H4?

Yes, but there are two things to consider:

1. The pinouts of the contacts may not match (in H4 mass often goes through the body).
2. In some vehicles (eg VAZ 2106) you will need to replace the base or adapter.

It is better to choose lamps marked "For ASh-4" or universal models with adjustable polarity.

Why does the high beam light come on when I turn on the low beam?

This is a typical problem when incorrect pinout. Most likely you have mixed up pins 2 and 3. Check:

• Correspondence of the wires to the diagram (see table above).
• Integrity of the light switch on the steering column.

If the problem persists, check the wires from the block to the fuse box.

How to check an ASh-4 lamp without a multimeter?

Can be used control lamp or connect the lamp directly to the battery:

1. Connect pin 1 (ground) to minus Battery
2. Serve one by one +12V to contacts 2 and 3 - the low and high beams should light up.

⚠️ Be careful: do not touch the positive wire and the body at the same time - this will cause a short circuit!

What to do if the contacts in the base are burnt?

Burnt contacts can be restored:

• Clean them up sandpaper (600–800 grit).
• Process WD-40 or contact lubricant.
• If the contacts are severely damaged, replace the base or block.

If the wires are burnt, cut off the damaged area and strip the insulation.

Is it possible to install an LED lamp in a headlight from a VAZ 2106?

Yes, but with reservations:

• headlight VAZ 2106 not intended for LED - glare effect.
• Choose lamps with the right light beam (for example, Philips X-tremeVision LED).
• After installation be sure to adjust the light at the stand.

⚠️ In some regions, LEDs in halogen headlights are considered illegal xenon - check local regulations.