HID bulb modules won't fit. 
Reason: 1. Inspect if you bought the appropriate bulb type for your vehicle. Select your vehicle make on the top left corner to display the bulb type for your vehicle. 2. Some vehicles require adaptor that can be custom ordered from us (ex. BMW E46). Please contact us for information.
　

HID turns on then both sides go out. 
Reason: It means the fuses are blown. Please check your fuses box according to your vehicle's user manual and upgrade the stock 10mA or 15mA headlight fuse to 30mA. The fuses are included in the package. The 30mA fuses are 100% safe for your vehicle, they won't cause problems such as damage your other electronic circuits.

HID will shut down itself sometimes. 
Reason: Inside of the HID ballast, there is a micro chip which is used to detect whether there is any potential problem. Any potential problems such as sudden high impulse or shortage of power input from battery or extremely high heat will trigger the self-protect and shut the ballast off temporarily. It takes about 3 mins for the micro chip to reset itself and the ballast will be working again. Once this happens, please turn off the HID and wait about 3 to 5 mins.

Inspection Procedure:  Please check the car battery. Check all connections between the bulb, ballast, & igniter. Check the vehicle battery terminal.

Only one light works, although both lights are installed exactly the same. 
Reason: 1. The polarity of one side might not match with the stock harness. 2. Fuse might be blown on this side. 3. Malfunctioned parts.
Inspection Procedure:  Check all connections between the bulb, ballast, & igniter. Check the bulb that does not work. Check the fuses. Use at least 30mA fuse if the stock 15mA fuse blows. Switch the failing bulb module to the working one to see if the problem remains. If the failing light now works, the bulb may be failed. If the problem still persists, the Ballast and/or Igniter may be malfunctioned. Check the Ballast and Igniter, switch it to the working side of the vehicle. If the problem still persists, the Ballast and/or Igniter is malfunctioned. If HID system works properly, your vehicle connections, battery, alternator, etc. may have problems.

The ballasts make electric noise when first turn on. 
Reason: This is very normal, the ballasts are absorbing powers from the battery to start up, that's why you hear electric noise.

The HID works initially but starts to flicker sometimes. 
Reason: It might be caused by damage bulbs or ballast.
Inspection Procedure:  Disconnect all the connectors immediately. Clean every connector with alcohol. Wait more than 5 minutes (reset ballast Safety Micro Chip) then reconnect or reinstall every connector. Then check all the connection between ballast and factory harness (Power Source); check all the connection between igniters and bulbs (yellow silicone connectors); check your upgraded fuse, they must be 20amp minimum. Remember, every connector have to be 100% well connected to each other. Do not loss mating or mis-wiring any connections.

HID will only work when the high beam is turn on. 
Reason: This situation mostly happens H4 kit because it has three pong plug rather than just "+" and "-". Make sure you have plugged those three wires correctly to their positions. Usually the combination is Yellow, Black and Red. For more details please check installation.

HID works when the engine is off, but if turning on the engine the HID will turn off itself. 
Reason: For some newer model cars such as 04 or UP BMW or 04 or UP Mercedes, the cars have onboard computers to restrict outsource components such as HID conversion kit or aftermarket MP3 Players. Therefore, the only way for such cars to install the HID kit is to directly plug the HID ballasts to the car's battery.

The HID bulbs changes color when first turn on. 
Reason: This is totally normal. At the beginning, the ballasts are storing the power from the battery of the car. Since the power has not been stabilized yet, the bulbs will might have different colors or even flicker a little bit. However, as soon as the power is stabilized by the ballast, the bulbs will become normal.

The colors or lighting effects of the two bulbs are different. 
Reason: 1. The level of the two sizes' headlight housings are not even, to adjust the headlight housings, please check here. 2. For new bulbs, there are chances that the colors are different for first couple hours of burning. The color will turn into normal once after that.

Inspection Procedure:  Inspect for damage in the light housing. Clean the lens of the light. Inspect the positioning of lights to ensure both are at the same angle to the road

How to make sure the HID kit will work properly every time. 
Tips: 1, turn on the engine first, before turn on the HID kit. 2, don't turn the HID on and off frequently. 3, don't install the HID ballasts and igniters near the engine nor anywhere the water can easily get onto. 4, make sure the connectors of the HID kit is tightened to the stock harness.

One or both light can't ignite initially. Bulb turns off after the vehicle just starts.  Inspection Procedure: You MUST DISABLE Daytime Running Light or "Auto Switch-On" functions before the HID installation, please click here for more information. HID system requires a steady level of battery voltage of at least 12V initially. "Auto Switch-On" and Daytime Running Light functions draws power from the vehicle battery which causes the HID system to fail to initially ignite.
If you have Daytime Running Light, disconnect the fuse or wiring of Daytime Running lights only. Please contact your vehicle dealer/manufacturer for more information.
If you have "Auto Switch-On" Headlight function, ensure to switch the function to "Manual Switch-On" headlight mode.
　

**To avoid further damages, always remember to start your vehicle before turn on the HID system.**