All Left rear Lights Gone MIA: "Left rear fot light defective" message

[Fun TC Driving]

Got the car late last night after its cross country journey. THRILLED with it! Went for a fantastic drive to the Oregon Coast. What a precise FUN-mobile! All went perfectly for the drive over there (70 miles); perfect 60 degree F sunny day. Then did a 15 minutes a DCFC charge there to insure we could — that the Plug and Play Cert wokred as it should. SUCCESS!

Then after starting out driving home, after ten minutes in the drive, the following warnings came up one after another within 30 seconds. All left side rear lights died. Rest of the car remained a dream.

After a 15 minute break on the way home for handmade ice cream, all the warnings went away and the light functioned perfectly again — well for first 20 minutes and then again all dead with the same warning notices.

Did something cool during the brak, but re-heated and caused them to re-die again? Any ideas as to what part failed to cause them all to die?

Sponsored

 

[Fun TC Driving]

Good point. I have not checked them all but I visually checked and confirmed that the fog light is dead and the left turn signal light is also not working .Also, we remember how when we our turn signals were actual light bulbs years ago, and when one went out the other one on that side of the car then blinked twice as fast. Another confirmation of the dead rear, left-side turn signal light.

Will be checking the brake and the tail lights themselves later tonight, Thanks.

 

[JonoNZ]

Check the fuse box for badly seated fuses?

 

[Fun TC Driving]

For more than just fuses. Far more than just 1/4 of the car’s lights going one and off… Here is our baby now:

Since I last posted our now 1,732 mile CPO (which again we just received 34 hours before) and had been such fun during that short time, this morning it went into full blown electronics/software meltdown. Starting simply as when I walked up to it, it failed to Auto Unlock the doors. Tried the other key fob. Nothing happened. Took a click on the key fob unlock button to open the car. Then when I got in and it auto started, it failed to remember my name on the top of the PCM screen. I then observed several other some failures as I pulled up previously-set things. The door mirrors would not fold back out. Most alarming was the it forgot our home AutoLift location (one trip in or out of our steep-aproned driveway transitioning in or out without full lift would mean a smashed front splitter or worse) — again it had remembered this Auto Lift location just yesterday when I first set it. Then it refused to lift up when I placed it in Off Road status — at least the first two times but when it did on the dash it visually showed it at its lowered position. Then it finally went up but would not come down even when I saw, again on the dash, it was getting lower. Nor would it re-set our currrent location (had moved it into the street at the perfect placement to enhance its chance to set/save our needed AL function. Now I was getting stressed.

When I next realized that more than a few of my other PCM settings were also no longer stored (other things that had worked on and set yesterday), I called the U.S. Porsche Tech Service phone {800) 767-7243} For over 1 hour 20 minutes we tried everything, but victories, while few were only sometimes temporary — e.g. a disappearance of one setting we had just re-set ten minutes before. He advised a trip to the dealership. We both discussed and agreed that the first place for their look at fixing it was probably electronic intermittency caused by a bad 12V battery cell or similar.

Damn, our new beautiful baby which we had just delivered 34 hours before, was going into full meltdown.

However, next came some initial positives. I called the Porsche dealership who said if I could get there within an hour they would look at my car immediately Still stuck at its Off Road height, he Porsche Tech Advisor said I could drive it the 33 miles to the dealership at a reasonable pace without damaging the car, OR, more than likely once I started driving it would lower itself.

Thankfully it did lower itself perhaps a block away when I got up to around 20 MPH. On the trip to the dealership (identical way we go to our daughter’s), I went throught a several mile country curvy, hilly stretch, e.g., a Porsche road. No one was on it this morning; pavement was dry. I put it into Sports Plus and two corners I used to take in my iX M60 at 33 and 43 MPH, I took this time at 42 and 51 MPH respectively — not even going full tilt. It was cornering so beautifully; inspiring handling confidence. Damn, I was smiling big time. This is a great, SPORTY vehicle. BIG FUN! This is the EV I always wanted (Taycan out due to my wife’s advanced arthritis).

Treated like royalty at the Porsche dealership. Never before been at a Porsche dealership as a service customer. Within five minutes (the usual SA walk around and similar), and yet all the time the SA was LISTENING INTENTLY to what I was recounting and what were my thoughts and suggestions, she said turning to an assistant after texting to someone else, “Tech X is ready to receive it in his work bay, will do a 12V battery test as a starter,” then turning back to me asked if I wanted to stay while they determined if that was the problem and if so they would put in a new battery and I could drive it home, or if they found something else they would give me a loner, and then shocked me by her APOLOGIZING, saying, “I am sorry we just gave out the last Macan EV loaner last night, but I have that almost new white Cayenne right outside which would be your loaner if your car needs more than the new battery.” I was impressed with their immediate plan of action.

40 minutes later she found me and said, “SORRY BUT IT IS NOT YOUR 12V BATTERY BUT IT NEEDS A BRAND NEW RECALL FOR A “SOFTWARE EXTENSION” AND ALSO SEVEN (7) CONTROL MODULE UPDATES. {Was originally put into service at the Atlanta Corporate headquarters on August 24th last year so an early, early made one.}

While driving away I was literally very sad leaving my new baby behind, but the Cayenne was more than okay to drive, and then every time I thought of how spiritedly I was able to drive our Macan EV through the twisties on the way there, I would smile some more.

So a time out for a while.

 

[Fun TC Driving]

Next chapter of the “lights out driver’s rear quarter:” saga: As above the entire left rear quarter lights failed three times previously but each when we stopped for 20+ minutes, they would back on coincidentally with the 3” diameter right driver’s pod big warning symbols in yellow going away when the lights came back on (and vice-versa)

The dealership and I wondered whether since there were all many sofrtware settings going away the two were software related. However today with the days long VR28.11 software extension download and other software updates finally being completed, there were not lights. Well for a short while, for while the Tech was in the car doing the last testing for the GPS location triggered Auto-lift to highest postion (which was now working before the software installs (but was working well he was testing it), the same light warnings came on — with of course the attendent driver’s side rear lights failing. While a bummer in one way, glad the Tech himself saw it happening.

So instead of coming home with us tonight, our Macan remains at the Porsche hospital. Leading contenders for the light failures includes an intermittent now-needing-to-be-traced wiring short, OR a lighting sensor that when it heats up it cuts out. Just hope it is identified and fixed soon of course; worse case would be horrid, that it is a sensor or equivalent with the closest replacement part not being in country. Oh well, enjoying the almost new, 2,600 mile, 2025 Cayenne loaner so not too bad after all. Though we MISS our Macan EV already!

 

[PrudentOcean]

If it was a sensor I would think the car would report that a light is out when it isn’t. My guess is that there is a wiring (continuity) fault, especially since it affects multiple lights on the same side.

 

[daveo4EV]

bad wiring harness is most likely root cause here - questionable if Porsche would diagnose that - good news is it's not a wear/tear issue - if that is root cause and the harness gets repaired/replaced it's not something that "degrades" over time…it will solve the problem once and for all.

 

[Fun TC Driving]

Update: The dealership worked hard and long, even assigning their Shop Foreman to my vehicle. They successfully downloaded both VR28.11/WSD0 and ASA, and that seemed to solve the light problem. After three and a half weeks it was released to us. What a great car! We just love driving it for the next five days.

But then again yesterday morning these four light warnings came up (the fifth time overall — with thankfully one surprising the Shop Foreman and my SA while they were in the car at the dealership testing it out).

After sharing info with my SA she advised to bring it back. On the way there, and I repeatedly during the first 1/3 of the 33 mile trip, re-tested the lights to confirm they were still not working (and the warning remained), until all of a sudden when stopped at a traffic light, I got a new warning, “Assistance Services Limited” for about 5 seconds and when then I noticed the tire pressure gauge had changed from reading “PSI” to “bar” (nothing I would even know how to do), and also at that same moment the light turned green and while accelerating away, put on my left turn signal and THE LIGHTS STARTED FULLY WORKING (such as not double speed left turn signal blinking but the regular speed as the right one has always functioned at). Still took to the rest of the way to the dealership. The SA looked up my car’s VIN while I was there and said, “there is no new software out since you were here last week, and as we know it was fully and successfully downloaded then.”

I left it there and they are further investigating as to what is next to finally and fully fix my car.

 

[JonoNZ]

I’m sorry to hear the problems have not been resolved, you have incredible patience, I’d be starting to lose it by now. To me, it does not sound like a software problem any longer, perhaps the wiring loom, or faulty control modules somewhere?

 

[Awaz]

@Fun TC Driving
That's a bummer, still niggles after waiting patiently for so long.
Hope it gets sorted soon.

 

[Fun TC Driving]

Thanks. What we have been experiencing is a true safety hazard, for when I approach a multiplane intersection and want to turn left, I put on my turn signal and brake, release the brakes, then re-apply them another time, to the person behind me it looks as if I am signaling to turn right. As a result of this, Porsche has said my car is not approved to drive for safety reasons. I expect with their massive commitment to do so, they have the Shop Foreman working on it and they are in touch with Porsche, they will succeed. I sure hope so. I want this very Macan to be mine and of course 100% driveable without concern that for the sixth time the lights would again fail.

Sponsored