BMW F10 Headlamp Ballast Xenon Control Unit 7318327 - Used Original Parts

Quick Answer

This is the right fix when an F10 xenon headlamp goes dark, flickers or cuts out once warm, and a known-good bulb or a left/right swap test shows the fault follows the ballast. A tested used Genuine unit makes sense in Malaysia because the original ballast is built to the same standard as the car, and heat, humidity and monsoon moisture are what wear these units out, not mileage. It also costs far less than a new dealer part, which is hard to justify on a car that is often already several years old.

Diagnosis and Common Symptoms

The xenon ballast (control unit) in the F10 converts 12 V from the car into the high-voltage ignition pulse and the regulated running current for the D1S bulb. When it ages, the failure usually looks like a bulb fault, so many owners replace bulbs first and the problem stays.

Typical symptoms:

• One headlamp does not light at all, while the other works normally.
• The lamp lights, then shuts off after a few seconds or minutes.
• Flickering or pulsing light, especially over bumps or when the engine bay is hot.
• Delayed ignition, or a faint clicking from the headlamp housing when the lights are switched on.
• Pink, purple or dim output even with a new bulb.
• Dashboard Check Control message for low beam or xenon headlamp failure, sometimes with a headlamp warning on the iDrive.
• The fault clears and returns, depending on temperature or humidity.

How to confirm the ballast is at fault:

1. Read the fault memory with a BMW-capable scanner (ISTA or equivalent). Look for low beam or xenon lamp entries in the FRM (footwell module) and, on adaptive headlamp cars, in the headlight driver module. These entries show a circuit or lamp problem but do not identify the ballast on their own.
2. Swap the D1S bulb from the working side. If the fault stays on the same side, the bulb is cleared.
3. Swap the ballast left to right if access allows. If the fault moves to the other side, the ballast is confirmed.
4. Inspect the connector and housing for water ingress, green corrosion or melted pins. These point to a wiring or seal problem that must be fixed along with the ballast.

Safety note: The ignition circuit runs at very high voltage. Switch off the lights, disconnect the battery and wait before touching the ballast or bulb connector.

Introduction

This is a Genuine Used BMW xenon headlamp ballast removed from an F10 5 Series. Each unit is bench and function tested before listing, so you are not gambling on a part with an unknown history. Genuine BMW ballasts are matched to the F10 headlamp electrical system, which is why they are usually more stable than unbranded replacements. You get a working original part at a fair price, backed by an exchange warranty.

Product Details

• Brand: BMW (Genuine)
• Model Compatibility: BMW F10 5 Series with xenon headlamps (confirm by part number 7318327 before ordering)
• Part Name: Headlamp Ballast, Xenon Control Unit
• Condition: Genuine Used (Tested Working)
• Notes: Drives a D1S xenon bulb. Check that the connector and mounting match your headlamp before ordering. Replace an aged D1S bulb at the same time if it is near end of life, since a weak bulb shortens ballast life. Inspect the headlamp seals for moisture, which is a common cause of repeat failure. Disconnect the battery before installation.