when i installed deautokey h7rc hids in my halogens before i went to projectors, i had the same issue you do. they would both fire and stay on no issue when it was warmer, once it got colder is when the same issue started
who you have. i had to do a few vagcom tweaks that deautokey recommended i do and run error cancellors. this should fix your issue ����
here is another forum post about a different hid kit, and some issues they ran into:
You're reading: HIDs not lighting up sometimes
in halogen equipped u need to disable the “bulb extender” option in vag com central electric, i think byte 19 or
20. its a dropdown menu, one for the front of the car and one for the rear. this option enabled sends a lower
voltage to the lights for a split second before sending full power. this keeps the bulb filament from being
shocked, therefore extending its life. when u have hid’s hooked up in place of a regular halogen bulb,
voltage prevents the ignitors from correctly firing in some hid kits, ddm being one, and u get flickering and/or
only one hid lighting up.
u also have to check the “xenon equipped with shutter” bit in cental electric i think somewhere between byte 11 to
15. i had the ddms and i needed to do both of these for the hids to consistently light up every time especially in
cold weather. doing just one or the other did not work for the ddm kits.
some hid kits allow for a lower ignition volatge so u may not need to do these changes for all hid kits but i know
at least ddm’s 35 watt slim ballast is one
who needs this tweaking.
unfortunately, when you place an hid kit into a halogen housing, the voltage won’t be 100% all the time when you are looking at vws. modifications and steps like above sometimes need to be taken.