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Most likely the connector/connection.

Have someone pry up lightly on the trunk lid as you actuate the button.

Once I tinted that HUGE greenhouse glass rear window to cut down on interior heating and the A/C heat load the dimming function no longer worked. So I use one of the "unassigned" seat/mirror memory buttons to automatically tilt the outside rear view mirrors downward about 5 degrees at night. Didn't know I had/have a sensitivety function ('01) on the wiper rain sensor, if I do. So, back to the owners manual.

You can leave PSM on and it will not "interfere" unless your seat-of-the pants "yaw" sensor is out of "calibration", or if your reflexes are simply too slow. Also, you could/can probably "initialize", "condition", your VC for more optimal autocross performance by driving aggressively, just to the edge of having PSM activate, in a turn circle about 4 cycles just prior to running the course.

The answer is.... You didn't buy your C4 for wintertime adverse road condition driving. At least I sincerely hope not. If you expected the VC to be an aid in the above conditions you were sadly mistaken, led astray. Absent driveline windup, wheel hop, or extreme tire wear VC implementations simply cannot have a QUICK attack rate, they cannot be allowed to come into play quick enough to prevent wheelspin/slip at startup, starting out or accelerating on a somewhat slippery surface. Traction control, on the other hand, will handle those instances very satisfactorily. Your C4's VC will stiffen up with semi-continuous disparate F/R driveline rotational rates, just exactly why you bought a STELLAR performing SPORTS car. And yes, absent TC intervention, the VC would eventually "stiffen up" and help you initially start out or accelerate from a lower speed on that slippery roadbed surface, but by the time it does so most driver's would probably be off the road and into a ditch somewhere. TC in the "short" term, plus VC, a good hand-in-hand working combination.

Malakas has a beautiful, imho, orient red 996... re the awd, this is one of the reasons I have a C4S. I'd driven a 993 and 997 and could feel, I think anyway, the pull of the front end coming out of several turns. I think I'm getting that same "feeling" now. I like the idea of the 5% minimum to 40% max of the front end. I dont think its just mental... but I've never put the car up on jack stands or roller stands to test the system. And you're also really right re the advertising. If the awd system did not work as advertised by Porsche, my God, can you imagine the repercussions, all the C4 owners from the very first would be up in arms. This is a great thread.... good info...thanks. jl Who has said, what has been said, indicating the AWD systems does not work as advertised..?? My '01 AWD RX300 has a VC mounted across the center differential but it NEVER comes into play because Trac activates the instant wheelspin/slip (front wheelspin/slip for F/AWD) is detected. Since the adoption of Trac made the VC virtually useless it was discontinued for the later RX models, the RX330 and RX350 and is not used on the Highlander or Sienna which have the same AWD system. Sort of like some folks putting a mechanical LSD in a 996 that has PSM.....

And this "color"..??

PSM activation... My personal experience seems to indicate that PSM's stability control aspects detect the "out of whack" condition immediately and then "stand-by", wait for a few hundred milliseconds, for the driver to take, make, corrective action/measures and if not then will use the FULL-FORCE of measures (engine dethrottling selective braking/unbraking, etc.) to reign the matter in. VC response MUST be delayed otherwise it would/might stiffen too quickly and provide a serious level of driveline windup and/or wheel hop/scrubbing in a tight accelerating turn. Something it MUST NOT do. A bit in the extreme but think about that circumstance in a 4WD/4X4 with the center diff'l locked. Broken thumbs, anyone..??? this explains the jolt I feel in my shoulder when the psm kicks in. M, if the awd didn't generally work as advertised all of us C4 owners would likely be involved in one massive class action lawsuit. I'll give you a full report when I'm back to running the same rubber all around. till then, I guess I'll be turning the psm off on twisty roads. ps: like we've talked about before, the color of your car is outstanding. best...j There would be no basis for a lawsuit, the AWD system works as advertised.... I would imagine the marketing hype goes something like, along the following line. "if the rear wheels lose roadgrip/traction the front and rear driveline rotational rate will differ and the VC will stiffen up accordingly and thereby increase the engine torque to the front wheels.." And if TC, Traction Control, always activates "first" and thereby prevents any significant level of traction loss, roadgrip, at the rear, what, then...?? On the other hand I would imagine a closely coupled series of hard/tight accelerating turns (autocross anyone..??) would result in the VC stiffening and putting more torque to the front.

In the battery compartment follow the negative battery lead to where it is attached to the car chasis. Make sure the connection there is good, tighten the nut holding the negative connection to the chasis while making sure the stud/bolt itself does not turn and is therefore welded FIRMLY to the chasis.

PSM activation... My personal experience seems to indicate that PSM's stability control aspects detect the "out of whack" condition immediately and then "stand-by", wait for a few hundred milliseconds, for the driver to take, make, corrective action/measures and if not then will use the FULL-FORCE of measures (engine dethrottling selective braking/unbraking, etc.) to reign the matter in. VC response MUST be delayed otherwise it would/might stiffen too quickly and provide a serious level of driveline windup and/or wheel hop/scrubbing in a tight accelerating turn. Something it MUST NOT do. A bit in the extreme but think about that circumstance in a 4WD/4X4 with the center diff'l locked. Broken thumbs, anyone..???

Personally I have strong reason to believe the VC in my '01 C4 is there for "show" only, marketing purposes. I believe I have read somewhere that disabling, turning off, PSM, does not disable PSM's Traction Control, rear "virtual" LSD, etc, aspects. If that is true then our VC can NEVER come into "play" and basically we C4 owners have been sold a "load of poles". But then that would be my second time. My '01 AWD RX300 has a VC. But it also has VSC & TC. My RX300 is primarily FWD and my experience has been that the instant front wheel slippage is detected the front wheel brakes are applied, BOTH front wheel brakes, and the engine is simultaneously dethrotted via EFI fuel stavation. So there is NO opportunity for the VC to come into "play", EVER..!! Which is undoubtedly why the VC was dropped from the Toyota/lexus F/AWD models subsequent to the RX300 series.

I suspect it would be the TC, Traction Control, Trac, mode of PSM that would "freak" and the only result of that would be dethrottling of the engine along with braking of (both..??) spinning wheel(s). Will disabling PSM also disable TC/Trac...?? Probably not, since it is the PSM's TC/Trac sub-mode that is used to "virtualize" a rear LSD. So, with PSM/TC/Trac is the VC worthless, can/will it ever come into "play".

Brake pads are NOT the place to look for "cheap" nor lifetime warranties. I always buy brake pads that are sure to eat rotor metal for lunch...!! On the other hand I guess a "lifetime" brake pad warranty isn't so bad if you happen to be 90 years old and fully expect to "go" soon anyway.

OBD II, Not sure how you have determined you have a bad condenser, but if you go to a generic AC shop they will usually put dye into your system and then use a ultravilolet lite to see where the dye has leaked out t odetermine which component or connection is "bad". In the P-car system, it logically is likely that one of the condensers has a leak as they are vunerable to road debris build-up that can cause some corrosion or possibly a rock damaging the condenser coil. If you already have gone thru the dye check routine to determine the leaky condenser, then you are well on your way to avoid replacing parts that may be OK. There are often time neopreme o-rings in the threaded connections that can also go bad and are a lot cheaper to replace than the condenser or other discreet components ( dryer, etc.). Good luck with your diagnosis and repair. demosan :cheers: do Thanks At the last service in Dec 07. the Porsche dealer reported that a condenser was leaking. I have only just bought the car and the air con works very well. The only thing I saw on one condenser is that it is stained. I am surprised that the AC is still working if it has been leaking for so long. So I dont really know if there is a leak. However I want to get a warranty on the car and this necessiates a 111 point check. I would need to get anything repaired immediately at full OPC prices and am therefore trying to fix anything that they would otherwise pick up. So if I still have working air con, when I change the condenser I will loose all the refrigirent. I was going to get it regassed from a KWIK FIT. Do all shops automatically do all the vaccing out of the system or is that something I need to request? Thanks When the system is operating the refrigerant within the condensor(s) is under a fairly high pressure so I would be surprised if you actually have a leak and yet the A/C is still functional over a reasonably long period of time.

A LED "load" equalizer is a resistor used in parallel with the LED lamp so that enough current flows to activate the turn signal relay. If you use all LED stop lights you will also need one in the stop light circuit so that cruise control will still work.

Since the factory recommended oil allows the engine to last, survive, WELL beyond 200,000 miles what's the point...??

The rotors would tell you if they needed to be replaced.

Might the TC, Traction Control, firmware on the Tiptronic model be quicker reacting than with the manual transmission. They are LOTS of very frustrated F/AWD SUV owners out there that are experiencing just how easily these vehicles get STUCK due to the TC system's QUICK, INSTANT, reaction. F/AWD TC systems react to even the slightest level of wheelspin/slip resulting from too much engine torque being applied for roadbed conditions. With F/AWD TC the brakes are applied to the slipping wheel(s) and the engine is dethrottled. Some of the newer RWD and R/AWD TC systems have a TC sub mode wherein some extended period of wheelspin/slip is allowed due to INTENTIONAL application of engine torque being applied. Say to get UNSTUCK by using a bit of wheelspin for rocking the vehicle back and forth. It is my understanding that while PSM can be turned off on our Porsches that does not include TC functionality, virtual rear LSD or otherwise. I haven't "forced" the issue with mine so I don't know for sure.

Sorry, I'm not so sure your test of the VC could be considered valid. Are you sure the "rolling" resistance of the front tires with the "good" VC wasn't the result of brake pad friction...?? Viscous clutches or couplings are "reactive" in nature, they do not provide much of a level of increased coupling co-efficient until teh fluid is heated via stirring by the two sets of opposing clutch plates. And which car turned more freely, the Tiptronic...?? When we dyno tested my '01 AWD RX300 for F/R torque distribution we found it initially to be 95/5 F/R. It was only after an extended period, 5-10 seconds, of simulated front wheelspin/slip (dyno braking of the rear wheels above the braking level at the front) that we were able to determine that the VC was actually functional, the F/R torque ratio went up to ~75/25. Initally, for a good long time, braking the rear wheels had virtually no engine loading effect. There are two primary ways the factory can "adjust" the "attack" rate of a VC, the base fluid formulation and the ability to add a volume of gas, gas "bubble", inside the hermetically sealer VC "canister". The latter method is used to delay the attack rate entirely. The gas volume must be compressed to "zilch" before the rising viscosity of the fluid (due to heating) begins to create additional coupling between the two VC clutch plates. Once the gas is fully compressed the fluid volume can no longer increase so its viscosity begins to rise. Is it possible that a different VC "formulation" is used on the Tiptronic vs the manual..??? And I'm quite sure, CERTAIN sure, that you cannot put enough energy into the VC by hand turning the front wheels to bring the coupling co-efficient into effect.

My '01 C4, factory delivery, came with Conti's. At about 8,000 miles the tires had become so noisy that one could not hear oneself thinking. Apparently Conti was aware of the problem so that arranged a refund immediately, no questions. I chose Bridgestones as the replacement, mostly because I have found them to be the quietest and most comfortable riding on my Lexii. WRONG, bad/poor choice. Within 5,000 miles a specialty bridgestone shop "technician" agreed that they were TOO noisy after driving the car maybe a block. So I am now running with Michelins. Anyone want the practically new Bridgestones...?? Fresh off the track at Daytona and otherwise maybe 5,000 miles. Factory rep was only willing to replace the Bridgestones with same brand or Goodyear(??). Finally talked them into donating, as a compromise, $400 to my favorite charity (no, not me!!).

"they should match..." Maybe not. First, I don't see a difference in the pictures.... But, be that as it may, the new head light assembly came with a new HID ballast. The allowable manufacturing tolerances for the ballasts may be a factor. Or is the new ballast even of the same manufacture?? One other point. Some of the newer HID assemblies have a UV rejection coating on the inside of the outer plastic lens/cover. But I don't know if the would result in a visible difference to the human eye. Maybe.

The connectors (battery end and engine ends) look clean. The alternator was bench tested good. The serpentine belt is tight and clean. The tensioner was adjusted upon re-intallation of the alternator. The tensioner is an auto tensioner. I'm wondering if there are some voltage test points procedures I could try... Your engine compartment is overheating.... But check and be sure the negative lead from the battery is FIRMLY connected to the body, tighten the nut. You might want to check the body connection for the negative side of the alternator also. The voltage regulator has a temperature sensing function so that as the ambiant temperature rises the battery is charged to a lower and lower level. That sensing element within the alternator voltage regulator might be failing and a bench test wouldn't be likely to indicate, detect, it. Once the voltage drops open the engine lid and cool the alternator with a fan and see if the voltage rises. Thanks for that. I wonder if it could be overheating since it drops within 1 minute. It could be the sensor as you mentioned in the voltage regulator of the alternator because I did an additional test-at the connector post from the battery to the alternator, I started the engine and measured at the connector, it measured above 13 volts but slowly began to drop to 12 volts and continued. I stopped the engine and disconnected the battery lead from the terminal and measured again, the reading was 12.6 volts. After reconnecting the battery back on the lead, I restarted the engine checked the voltage again it was above 13 volts BUT this time I pulled the battery lead off the connector and measure the voltage on the alternator post (without the battery connected) and it measured above 12 volts but began to drop to ~10 volts. I reconnected the battery and retested to 12+ volts. So the only conclusion at this point is that there is something within the alternator that is defective and it doesn't show up on the bench test. Any thoughts as to whether I continue other tests or "bite the bullet" and replace the alternator which of course is non-returnable should it not solve the problem.... Caution..DANGER...!! Never, NEVER disconnect the battery from the alternator circuit with the engine running. The battery is an integral part of the method of regulating the output voltage of the alternator, without the battery you would possibly get 100 volt spiking from the alternator and that would most certainly damage some of the electronic components. It looks, reads as if you disconnected the alternator output lead from the battery and thus all the circuit loads...I HOPE.

The connectors (battery end and engine ends) look clean. The alternator was bench tested good. The serpentine belt is tight and clean. The tensioner was adjusted upon re-intallation of the alternator. The tensioner is an auto tensioner. I'm wondering if there are some voltage test points procedures I could try... Your engine compartment is overheating.... But check and be sure the negative lead from the battery is FIRMLY connected to the body, tighten the nut. You might want to check the body connection for the negative side of the alternator also. The voltage regulator has a temperature sensing function so that as the ambiant temperature rises the battery is charged to a lower and lower level. That sensing element within the alternator voltage regulator might be failing and a bench test wouldn't be likely to indicate, detect, it. Once the voltage drops open the engine lid and cool the alternator with a fan and see if the voltage rises.

No problems other than I may have had to modify the current sensing resistor in the solid state turn signal flasher relay. Converted all of our vehicles to LEDs and I don't remember which ones required modifying. Oops, almost forgot. The 996 cruise control will not work absent stoplight resistance load equivalent to at least one incandesent filament. I used a 12 volt relay with a 9 ohm resistor connected via the N.C. relay contacts.

HID "bulbs" now come in a variety of "colors". Since human development has been primarily under our sun our eyes are more attuned, receptive, to 4300K. Other colors are only to impress oncoming drivers who you will likely never meet.