Im having the same issue with my ddm tuning hid kit. I checked all grounds and connections,battery, alternator are all strong. Cant seem to figure out the issue.
Input please

 

so it'll be on then just turn off?? if thats the case, the ballast or bulb is going bad... if one just doesnt turn on when you turn them on, then you need to run a relay harness.. the amperage the hids need to turn on is much higher than halogens, so it wont fire up the ballast.. you need to run a relay harness..

 

thank you i am having the same problem but i belive its the ballast

 

relay/wiring harness.
first switch the ballast and see if the problem follows the ballast. if it does then you just need a new ballast. if not then its a relay problem