Bi-Xenon beams too high
 

I have an 08 Cayenne S and I see that my beams are aimed too high. I tried adjusting them per factory manual but they still seem very high.
Something interesting happened on saturday. I hit a bump, headlight adjustment light came on the dash and for the 1st time the headlights were pointing down instead of being too high. Unfortunately, once I stopped and started the SUV again, the lights went back to their old high setting.
What gives? How can I fix this?
Thanks in advance.

A PIWIS interrogation should be able to diagnose the leveling mechanism and feedback signal. Based on a limited description, it sounds like the issue lies with the (integrated) level sensor.

Toby Pennycuff is the forum resident expert on all things BiXenon.

I sent him a PM as well.
Based on one of the posts on Rennlist, when the headlight mechanism is turned on, it performs a test/adjustment. The headlights angle all the way down 1st, then they angle all the way up and then settle in the middle. My headlights go down, then all the way to the top but never settle and I know they are aiming too high.
I know there is a problem because for the 1st time they actually faced down when I hit a bump and stayed there until the car was turned off. I have tried adjusting them thru the hole but they are still too high.
Hope that helps.
Raj

This is going to require a PIWIS session at the dealer. Level floor, re-program height specs on both sides and re-test. Figure an hour of a tech's time. This is not a DIY procedure unless you have access to a PIWIS. Sorry.

Toby

Thanks Toby. I wanted to confirm before to drop down the $$. I would guess this not covered under CPO?

It should be covered under CPO, since the headlight leveling mechanism is not classified as a 'wear item' ... like brakes, bulbs, fluids, etc.

Another possibility is mechanical binding, but as Toby mentioned, it is all speculation ... the PIWIS will quickly determine the cause and part(s) to be replaced.

I would just drive over the bump again.

:rockon:

Agreed, but what happens is that the fault code is a soft code and it doesn't get stored. It goes away at next start. As you mentioned, the factory tool should be able to determine fault.
Raj

Sounds great but suspension is wear and tear and I dont want to break something else that is NOT covered by CPO :).

While we are at biXenon, I get the feeling that the light is "loosing power" over the age !
(Talking about CS, delivered Feb 07, and feel that at the "beginning" the light were much stronger !)
Or: do biXenon have a "life time" ?

Apparently - maybe. I've read reports from people who replaced factory bulbs with new factory bulbs and claimed increased light output. Not sure why this would be since there is no filament to wear - but if there are deposits on the inside of the light capsule - that might explain it..

I've also replaced the Xenon bulbs on my '03 Audi RS6 with OEM bulbs and the light output is increased. I also replaced them on my '06 CTTS but that was because the passenger side was giving me a fault occaisonally so I can't say for sure that the Cayennes are brighter but I don't get a fault anymore.

Yes, gas discharge tubes have a "lifetime".
From a familiarity perspective, this is why plasma TV's have a "10 year life" .. after 10 years, the luminosity is reduced to 50%

Even solid state lighting has a "life time", which is why White LED's (most commonly used as backlighting on LCDs, having replaced CCFL's due to mercury concerns) also have a time period where their luminosity output drops.

In summary, physics and entropy is a bitch who can not be cheated

Update and Good News.
Took the car in to get the lights checked at the dealer.
They found the sensor to be faulty and it is covered under CPO! Nice.
Part should be in by wednesday. Will report after fix.
Thanks everyone.
Raj