Headlight switch or Ballast?

For the last couple weeks I've been having a problem with my passenger side low beam headlight (Litronic). When I first got the car, I also had a problem with the same light - replaced the bulb and wit worked, but soon stopped working again...seeing as I had just replaced the bulb, I got a used but working ballast unit and replaced the old one. It has worked fine for the past year and has now started to act up again. Whatever the problem is, it's intermittent, and I can get the light to turn on sometimes (usually after switching on and off several times) leading me to believe that maybe it's the switch (after reading through several threads about it). Any ideas? Surefire test/trouble shooting proceedures? Thx in advance!! ** Oh yeah, forgot to mention, my left directional has also just stopped working - haven't checked the bulb yet...

My headlights would not come on every time. Sometimes if I rotated the switch more harshly it tended to work better. Also noticed it was a bigger issue when going from parking lights on and then switching up to headlights. Anyway, bought a new switch (Amazon $155) and they have been working first time, every time for the past three months. YMMV

Hey, thanks for the reply. Yeah, that's sort of along the lines of my thinking especially after my left turn signal recently stopped working as well. Anyone else care to chime in with similar anecdotes?

See this thread https://rennlist.com/forums/996-foru...ast-issue.html I don't have the wiring diagram so cannot confirm if there are two separate contacts in the headlight switch to individually supply voltage to each headlight, if there is only one switch contact then it wouldn't make sense that changing the headlight switch is the actual fix the problem with only one headlight. I was having some issues late this season with the driver side light not firing up reliably, being a Canadian car, the HIDs come on automatically as soon as I start the car, there may be a circuit to power the headlights independent of the headlight switch, given the intermittent problem has always been on the driver's side the 3 times I have had issues over the last 3 years, I am interested in finding the wiring diagram for a Canadian car so I can troubleshoot/isolate this issue better.

Guys, you can download the whole workshop manual here including the wiring diagram http://www.ganino.com/games/Porsche%...als%20PDF/996/

Thanks Ahsai, will download and study, hopefully there is an addendum for Canadian cars to show how the DRL scheme works, i.e. if there is a separate relay powering the headlights independent from the headlight switch.

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Yes, the Canadian/USA lighting wiring is in sheet 2 of the wiring diagram. Grab them before they are gone

Deoxit! Get a can take out the headlight switch and spray with the fine tune into the openings in the front of the switch around the center . Fixed mine right away!

Thanks for all the replies! And a huge thank to Ahsai! That's a lot of info :-) I'm going to try to spray out the switch first before I throw $150 at it...we'll see!

Dporto, yes, alot of info especially you move up and down the folder directory Don't replace your headlight switch yet. I'm with aviography on this. Your low beams are protected by fuses A9 and A10 but they are both powered by the same circuit/source. The sources are the light switch and the DRL relay, if equipped. So any one sided problem really points to the bulb, ballast, and the wiring harness on that side.

Ahsai, great minds think alike.

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Picked up some de-oxit today and sprayed into the center shaft (maybe a "slip-ring" style connection inside?). The light is working again - it took about 4 or 5 twists of the switch for the contact cleaner to work, but it seems pretty consistent now...we'll see what tomorrow brings.

^I need a scientific explanation of this fix haha

^Hmmmm^ Scientific eh? How's this : "DeoxIT� D-Series contact cleaner is a fast-acting deoxidizing solution that cleans, protects, lubricates and improves conductivity on all metal connectors and contacts. Use as a general treatment for connectors, contacts and other metal surfaces, and on non-critical metal surfaces with severe oxidation and corrosion. If the metal surface is discolored, it is severe. DeoxIT� dissolves the contamination and protects the surface. For reference, DeoxIT� has approximately 20% cleaning action. KEY FEATURES: �Improves Conductivity �Deoxidizes, Cleans & Preserves �Reduces Intermittent Connections �Reduces Arcing & RFI �Reduces Wear & Abrasion �Temperature Range, -34 C (-29 F) to +200 C (400 F) " right from the Caig website. In my case there was definitely arcing involved because I could hear it (or the ignitor firing) through my stereo...When the light actually goes on you don't hear any of this...How's that for scientific?

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What I meant was there's a single contact inside the switch and a single wire coming out which supplies power to both lights per the wiring diagram. So if the switch is the problem, you would think either both lights work or they don't. One possibility is the corrosion in the switch caused voltage drop to a level that is marginal for the pax side light to operate but was still enough to light up the driver side due to different tolerance of the lights.

Ahahhhhh Ahhh-Sah-EEEE...in that case you're saying the increased resistance created by the oxidation/corrosion/poor contact, in addition to the longer wiring run (= greater resistance) creates a low voltage/current condition which isn't strong enough to ignite the Xenon light...Sounds plausible to me

Yes about the increase resistance. The different length of wires between the lights are negligible. I'm thinking more along the line of different internal resistance of the ballasts. Since they run in parallel, they will draw the same current ONLY if their internal resistance are identical. Maybe their internal resistance diff enough due to age/wear/natural tolerance, when limited power is supplied due to the corrosion in the switch, the left ballast draws more current than the right ballast thus starving it from power. BTW, Deoxit is indeed great stuff. You may want to spray the headlight sockets too.

Is there a up grade for lights on a 2001 996 TT ?

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I.E. De-Oxit...Yup, did that prior to starting this whole switch excercise. I've been using de-oxit in the recording studio for many years (does wonders for patch bays)...