Ford focus mk3 2011 LED headlight problems !!!

[Danny19833]

So I what to upgrade my H7 headlights to LED's so got the LEDs with the error free link up for them work totally fine no errors but as soon as the engine is turned on the lights go off after a few seconds, can anyone help what am I missing ?? or is there a kit especially for the mk3 ??

[Phil21185]

You can't usually just put LED Bulbs straight in the halogen holders - there's too much current supplied by the electrical system, as well as dimming being controlled by pulse width modulation (ie alternating on/off patterns) rather than voltage modulation.

There are kits available, but these often come with large heatsinks to dissipate the excess current and either don't fit well, or partially melt the headlight reflector.

Also, I believe it is illegal to put LED Bulbs in headlights - something to do with the dazzle and incorrect light patterns.

[JW1982]

On 9/11/2019 at 7:49 PM, Danny19833 said:

So I what to upgrade my H7 headlights to LED's so got the LEDs with the error free link up for them work totally fine no errors but as soon as the engine is turned on the lights go off after a few seconds, can anyone help what am I missing ?? or is there a kit especially for the mk3 ??

The Focus MK3 has a bulb check system that measures the resistance/power consumption of the light bulb when the ignition is on. In case the resistance/power consumption is out of tolerance the system assumes that the bulb is broken and switches off the power to the bulb. Most aftermarket LED Bulbs or HID kits (even the ones advertised as error free)  have a different resistance/power consumption as the stock halogen bulb and will not work correctly.

Another problem is that the halogen bulbs are powered by a pulse width modulated (PWM) power signal. Most aftermarket LED Bulbs or HID kits are not suitible to be powered with a PWM power signal. The PWM power signal will reduce the life expectancy of the LED Bulbs or HID Kit drastically.

Both of these problems can easily be solved by changing the headlight setting inside the Central Car Configuration. Parameter value # 14 (Headlights) need to be changed in hexadecimal value 03. This setting was originally used on USA vehicles fitted with HID headlights with manual height adjustment but is also perfectly suitible for aftermarket LED or HID headlights. This setting disables the bulb check system for the dipped beam and powers the dipped beam with a steady battery voltage instead of the PWM power signal.

 

Be aware that the original reflector headlights of the Focus MK3 are not designed for aftermarket LED or HID bulbs. Apart from being illegal iIn most countries both the light output and beam pattern are usually insufficient. It is highly recommended to only install aftermarket LED or HID bulbs in projector headlights.