Electrical glitch with lights
04-01-2018, 08:19 PM
#1
Electrical glitch with lights
I have been having an intermittent electrical problem, hopefully someone on the forum as a thought on diagnosis this. Car is a 2013 991, 3.4 coupe, 42k miles on the clock. A few weeks ago as I was leaving my house, I got a few warning lights on my dash, first telling me my running light was out, then brake light, then headlight. As I was checking everything the turn signal alarm went on as well. All of the alarms were for lights on the drivers side of the car. After a short drive it went away and then came back again. First thought was a battery issue, so I replaced that as the battery was over 5 years old and was a bit low voltage with the car off. The problem went away until today, when I got alarms that the left turn signal, brake light, and running light were out. Drove the car for a few minutes, left it alone, restarted and all was fine.
Any thoughts on diagnosing this? Fuses seem ok. Maybe some relays are the issue but I can't imagine a particular fuse that would cause a problem Iike this. I hate to bring it to a stealer since it is out of warranty. I haven't been able to find a wiring diagram or a map of the different control modules to see what even controls this stuff.
Any thoughts on diagnosing this? Fuses seem ok. Maybe some relays are the issue but I can't imagine a particular fuse that would cause a problem Iike this. I hate to bring it to a stealer since it is out of warranty. I haven't been able to find a wiring diagram or a map of the different control modules to see what even controls this stuff.
04-01-2018, 10:14 PM
#2
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Usually a battery issue. However since you changed....any possibility that you have wiring damage due to rodents / pests?
04-02-2018, 12:01 AM
#3
It looks like the Exterior Lights section starts on page 2932 in the maintenance manual, which can be downloaded from the first post of this thread. Good luck in your troubleshooting.
04-02-2018, 12:31 AM
#4
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Electronics are so complex on a modern 991 with its Can-Bus system it will likely require a hookup to the Porsche dealership computer to diagnose. We are many years beyond checking fuses as issues for most of these kind of issues. While you are at the dealer, have them re-index the new battery so you get the correct charge rate, will make your new battery last longer as well.
04-02-2018, 09:05 AM
#5
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Lets hope it's simple.
But rodents and water can kill electronics very quick.
Keep the car in a garage? Have mice? Carpet wet?
Car isn't blue .... is it?
But rodents and water can kill electronics very quick.
Keep the car in a garage? Have mice? Carpet wet?
Car isn't blue .... is it?
04-02-2018, 09:14 AM
#6
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It seems like this notion was myth-busted in the other "DIY Battery" thread that has been running a few months. Your other comments are spot-on.
04-02-2018, 10:30 AM
#7
I've had similar problems. The first set of problems was solved by replacing the key fob, it was a warranty item. The second set of problems, on two separate visits to the dealership, were solved by replacing portions of the wiring harnesses. Turns out I have mice/rats/rodents in my garage and environs. I've since put out traps, bait, and sticky pads for the little varmints. The service manager at Porsche of Fremont told me that European car manufacturers have had to switch to a plant based wire coating to be more environmentally friendly, and that attracts rodents. Good luck.
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04-02-2018, 10:52 AM
#8
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Plus - I can't remember what I posted in the other thread...lol
04-02-2018, 10:52 AM
#9
Thanks for all of the suggestions. I am going to pull back some carpets to take a look at wiring, but didn't want to just start ripping stuff apart. That link to the service manual is exactly what I need, I don't know how I missed that post! I have never seen any evidence of rodents in my home garage, its a fairly new house that is very well sealed so hopefully that isn't the issue.
04-02-2018, 02:14 PM
#10
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Start under the car: engine bay, behind wheel well liners, inside the bumper covers, plenum behind the forward firewall. Rodents don’t materialize inside the car. They start in the first enclosed spaces they can find.
05-02-2018, 01:52 AM
#11
UPDATE.....I checked a lot of the wiring, fuse boxes, etc. Everything was in tact and no signs of rodents. I haven't had any issues with the car in a month, I only had one issue with the lights a few days after I replaced the battery. My best guess is that even though I replaced the battery it needed a good deep charge from a long drive.
Perhaps this is the reason the dealers claim to need to do a "reset" with a new battery? It's not the battery per say but the way the car is charging it and using electronics in the time period after the battery is replaced?
Perhaps this is the reason the dealers claim to need to do a "reset" with a new battery? It's not the battery per say but the way the car is charging it and using electronics in the time period after the battery is replaced?
