GRIEHL

hey folks, bought a 2012 Cayenne yesterday. I bought it with the headlight control fault displayed. The owner I got it from said that the a HL control module was replaced but programmed for a PASM vehicle, how he knew this I have no idea. Anywho, got home and found a dead rat on the splash pan, yuck! I am thinking maybe I have a chewed wire. I have my wife's 2011 we are replacing still at house swapping trim and wheels and so on, so, I can swap parts.

I swapped headlights with no change. Everything works sans the corning lights.

I would like to put eyes on the control module, (NOT the ones on the headlights) but I can not find it, any help? I looked around and did not see any chewed wires but I may be looking in the wrong place

Also, does anyone know which fuse to check? I would normally check them all but I do not want to cut power to a system if I dont have

ok thanks!

deilenberger

Headlight control circuitry

The one you're looking for is the front body control module - located up under the dash on the port side of the vehicle (drivers side in US..) The fuse numbers are shown in the diagram. IIRC - the body-control modules must be programmed to the vehicle since different vehicles can have different lighting options. This may require a PIWIS - which means it's dealer time. The person you bought it from probably didn't have that done - so there is something not coded correctly for your vehicle.

GRIEHL

Yea, taking it tomo. Maybe I will get lucky with a software fix

slavie

Have you read the codes? When I simply swapped the module on my 957 the headlights worked without level adjustment and cornering lights, and the error code stated that the VIN changed and needs to be re-programmed. I had the headlight system fault message as well, of course.

Dealer quoted 1hr for programming the HL control unit to the VIN. In your case, if you don't know the codes or what is wrong with the system, you may get lucky and be done with just re-programming, or unearth a bigger issue.

Also, don't know about 958, but at least on the 957, both L and R modules must have the same revision number or it will not work and will not program. If that's the case, the dealer will tell you that you need a new pair of modules (unless one of yours is already the latest) at ~$600 each + programming. I actually have a matching set of B revision 958 ballasts if you're interested (they worked but would not communicate on CANBUS on a 957 for me, had to get 957 ballast),

GRIEHL

Slavie, thanks for the info. I act managed to find a shop locally that can read and program (and code) any vehicle. We read the codes and had the wrong vin and there is a HL module in the car for a vehicle with PASM, so, looks like the PO had a used module installed. My guy was not able to re-map the module in the car, maybe the dealer can. I am thinking I will need a new HL module which I sort of expected. I will keep you in mind if they say I need ballasts

thanks!

slavie

I am not aware of any tools besides PIWIS that will code these lights. Not saying they don't exist, just that I haven't found any - I've tried Durametric Pro (can see modules and read codes, no programming), VCDS (does not see HL module), and iCarSoft thing doesn't do it from my research (though have not tried myself, don't have one).

Did the shop check the PN's of the Left and Right module while they were at it? Durametric can read PNs with sub-revision. If they are different revision (there was A, B, and C), then I'm 98% certain they could not code them for that reason, and neither will the dealer. Pop the headlights off (really easy, check youtube videos), and take a look at the aluminum ballast numbers on the bottom.

deilenberger

This is a WAG - but I wonder if Porsche uses the front body-control-module (also serving as light-control-module) as the secondary secure storage spot for the vehicle mileage?

BMW has used their light-control-module (LCM) for that for years - which is why a used one is worthless.. the data can't be reset. Only a new one can be installed and it reads the mileage from the instrument cluster and programs it to a stored version of the VIN#. If the instrument cluster fails - one has to be obtained (new or used) with fewer miles than the headlight module has stored in it - and then it resets its mileage based on the stored mileage in the LCM. If they don't match - a tamper dot appears next to the mileage display in the cluster. I'm sure Porsche has something doing the same thing (really became mandatory with the advent of leasing cars with limited mileage leases)..

slavie

Nobody at Porsche will offer up the answer to that question, of course, so we can only make educated guesses. From what I've been able to gather, there are various levels of protection for the VAG electronics modules - some don't have any protections at all (such as the tow module, CD changer and Phone module in the PCM system), some are tied to the VIN and can be recoded, which I believe the HL modules are. The speedo cluster has the mileage limitation you're describing, where a replacement can only come from a lower mileage car or new from the dealer. The body control modules and gateways have to be cleared by the dealer before they can be re-programmed (maybe the HL are same). From what I've read, part of the reason for this is to combat theft - when a module is to be re-programmed, the PIWIS system will ring Germany and check the existing VIN against a DB of stolen cars, and will not re-program a module if so. This effectively makes stolen vehicles less attractive as their electronics cannot be re-sold.

This was not the case with 955 Cayenne, where the HL modules could easily be reprogrammed even by VCDS without any VIN checks. But, Cayennes had a big problem with headlights getting stolen off cars, so that may have compelled them to tighten security on 957 and newer cars.

Also, another reason the headlights have to be programmed and not just "activated" as part of the coding is setting the headlight normal level. Before that happens, the headlight will default to the lowest position even after you clear the VIN hurdle.

GRIEHL

well, the dealer was able to re-code it, charged me two hours -- but that is cheaper than a new module, so, I am happy!

wifedrivecayenne

Hello. We had an aftermarket tow hitch installed to pull a 21' Airstream on 2013 Cayenne Diesel. The install went well. All brake lights turn signals etc work fine. Except the installer did not install a control module mainly because the trailer has a Prodigy wireless brake control system that works very well. There trailer has sway bar system and tows great. Towed trailer 1175 miles. The only issue is that when the 7-pin connector is connected to car, the "Fault headlight control" message is displayed. Also, the car will not turn off when it is connected. That is, I can turn the key to the off position, but the car doesn't turn off and the key isn't released from the socket. So, for the long drive, when it was necessary to turn off the car, we disconnected the trailer. Any thoughts?