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Litronic Lighting Problem

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This problem has plagued me for quite some time, though I'm just getting around to trying to fix it now. My low beams work fine, and when I switch to high beams the sheilds do the right thing. The problem is that the drivers side halogen (high beam) bulb actually dims. Also, with the high beams switched on, my left turn signal no longer works. Has anyone else experienced this same scenario? Seems almost like there's a crossed connection somewhere that's causing too much resistance - just not sure how to go about trouble shooting it...

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The car is 20 plus years old...

Pins in the connector can push out. I had this happen on my MY99.

Connectors can break/crack. Has happened to others likely from slamming the headlight back into its lock.

Corrosion can occur if the seals are damaged. Look for moisture inside the housing.

Can even be a bad contact on the bulb or bad bulb.

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Had a chance to look a little further tonight. I opened up the back of the housing - all the wiring looks good (no cracked insulation or anything like that). I also checked and cleaned the connectors with De-oxit. No help, but I also noticed that occasionally if I use my left turn signal with the hi beams turned on both headlights cycle up and down in time with the flasher... if I turn the hi beams off and then turn them back on and hit the directional again, it just doesn't work - the headlights won't cycle up and down... rather bizarre behavior, but it definitely points to some interaction with the turn signal and the high beams... a relay perhaps? 

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Just a guess...but how about checking and cleaning the ground point for the headlights/turn signals?  Not sure where it is but there must be a common ground point somewhere in the frunk area, maybe under one of the covers next to the battery or near the brake master cylinder.

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Hey Joe, yeah probably a good idea. I just noticed something else also (just got back from a drive)when I pulled up my driveway I sat and messed around with it for a few minutes. A couple times I got the turn signal to flash once or twice before it stopped. This leads me to believe it's a contact - maybe in the stalk itself? I've read of people having problems with these - and all the wiring and sockets seem to be good. I'll check it some more tomorrow morning when it's light out (hopefully not raining).

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Huh.  My thoughts in this order...turn signal in the steering column, contacts need cleaning, the light switch, replace the electrical part of the light switch, and the electrical part of the ignition switch which is known to cause all kinds of gremlins.  You may even try pulling the headlight and use a multimeter to test the pins while turning on headlights and turn signals.  Electrical problems are tough to solve.

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+1 ^^^ Still haven't solved it. In the interim I've realized one more thing - The left turn signal also doesn't work if the fog lights are on (right signal works fine). So, it seems that for some reason either the Hi beams and/or the fog lights are shorting/canceling the left turn signal, and the left high beam is dimmer than the right... I just don't know where to go with this. The light switch is new/good as I changed it out about a year or two ago (I used to have a problem with the right low-beam/hid not lighting intermittently - the new switch fixed it (I also had the current problem with the old switch so that wasn't it). Not sure about the ignition switch - I suppose it could be the problem but it's never acted up otherwise (i.e. turning too far, not cranking, etc...) so I'm a little hesitant to start messing with it.

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  • 10 months later...

Somewhat similar problem. Moderators please move to a more appropriate location if needed.

2001 3.4 C4 Coupe Manual; UK RHD Car. Factory fitted OE Litronic headlamps.


Day 1 of problem, drive to work in dark, I noticed the RHS (my drivers side) headlamp stayed in dipped position (I noticed this when on the road, not when I first turned the lights on in the garage). I turned lights off/on a couple of times (Microsoft solution) no change. Drive home from work later is in daylight.


Day 2 of problem, both lamps stayed in the dipped position when I turned on the lights in the garage, and have remained so.


I have checked the sensors, they are both intact and in position. No codes showing. I have disconnected and reconnected the lamp units. No change.


What work was done immediately prior to this? I had the 4 plastic panels off of the underside and replaced. Air-con system had a service/re-gas, so a bit of rummaging around in the frunk front left corner.


So where to go next....... 

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Thanks for that Loren, all pins present and correct & the wiring looks good as new.

I checked the Bentley Manual which has little to say on Litronic levelling faults, but did detail a test to do “if lights do not behave as expected in the test, bring to Porsche specialist to diagnose”.

Seems the test may be a reset of the system, as the lights did behave as expected and are now working as they should.

The test is simply to turn on lights, then start the car, as opposed to how I would always start the car & then turn on the lights. The lights dipped and the motors sounded like they overrun for a little longer than required. Now when I start the car and turn on the lights they dip and level as before, and when I select high beam the dipped beam raises.

So all boxed up and ready for the morning run, fingers crossed that this is sorted.

Again thanks for your very prompt reply.

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