# MK5 Intermittent Headlights... is there a common ground?



## doublec4 (Feb 26, 2009)

2008 GTI with factory xenon headlights

I'm trying to diagnose an issue with intermittent headlights. First it began with my passenger headlight flickering on and off at random. I put brand new Morimoto bulbs in from The Retrofit source and still had the same problem. Then I swapped the igniters from driver to passenger... for a short period of time the problem switched over to the driver side so I figured the problem must be the igniter. I disconnected the wires going to the igniter so the bulb wouldn't get ruined from being turned on and off. While waiting a week or two for my igniter replacement to show up in the mail... the passenger side starts flickering now too. So now I'm thinking the problem can't be the igniter? 

Fast forward to today... igniter shows up in the mail and tried to install it... turns out rockauto sent me the wrong one. I put the original back in on the driver side and drive the car around for 10 mins... driver side headlight turns on and off at random still.... once or twice the passenger side also went out leaving me with no headlights.

I'm wondering if the entire headlight system shares a common ground? I'm having a hard time believing that either both of my igniters or both of my ballasts could be on their way out at exactly the same time.... 

Can anyone else give me some hints on where to start? I don't want to just throw parts at it since ballasts and igniters are insanely expensive.


----------



## dennisgli (May 17, 2003)

doublec4 said:


> I'm wondering if the entire headlight system shares a common ground?


I don't have a wiring diagram for your car but yes, I would think there is just one ground connection. And it may provide the ground for things other than the lights.

It would be worthwhile to check to see if you are getting full voltage at the ballasts.


----------



## doublec4 (Feb 26, 2009)

dennisgli said:


> I don't have a wiring diagram for your car but yes, I would think there is just one ground connection. And it may provide the ground for things other than the lights.
> 
> It would be worthwhile to check to see if you are getting full voltage at the ballasts.


What would be the likely issue if I'm not getting full voltage at the ballasts? 

I removed each ground and cleaned it and reinstalled it... they seemed fine. I also removed each headlight, cleaned all of the contact points and made sure there was no loose connections inside of the headlights. 

I'm having a hard time believing that both ballasts, or both igniters could have stopped working intermittently at the same time. I even replaced the CECM today and I have the same problem. As of lately my rear inner parking light (passenger side) is also permanently out. Bench tested the light and its fine... I hate electrical gremlins :banghead:


----------



## dennisgli (May 17, 2003)

doublec4 said:


> What would be the likely issue if I'm not getting full voltage at the ballasts?


Voltage drop somewhere in the circuit. No way to tell unless you check.


----------



## doublec4 (Feb 26, 2009)

I couldn't deal with it anymore. This is what I did for anyone interested:






Now they work again... and for a fraction of the cost.


----------

