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Electrical - Tail light and alarm malfunction

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New to the forum and i am having a difficult time navigating.I am not even sure this was the way to ask a question by posting a new topic... If not i apologize.

I bought a 2002 boxter with automatic transmission and only 68,000 miles. First boxter and I know very little about the car. Had the car sit in the garage for a couple of weeks after the purchase and found it completely dead. The used car dealer that sold it to me changed the battery. Since then I seem to be having all kinds of annoying electrical problems. The key fob decided not to work any more. I replaced the key fob battery twice. Still nothing. My driver rear running light does not work, worked fine before. I checked the bulbs, all are fine. So are all the fuses. My driver front running side marker light does not work either. Nothing major but annoying nonetheless.

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Welcomt to Renntech  :welcome:

Yes, this is the right way to ask questions or share technical information.


Regarding the tail lights, the light switch supplies power to fuse A3 then the power is split to the right front side marker and right rear light. Similarly fuse A4 supplies power to the lights to the left side marker and left rear light. Therefore, the front side marker and the rear light should turn on/off together (on the same side).


The first thing to check is whether fuses A3 and A4 get power when the light switch is turned to the "low beam" position using a multimeter. You can also pull the light switch and then turn left or right to turn on the parking/rear lights on either side.


Then you will need to check if there's power to the rear light sockets when the light switch is turned on.


There's a way to reset the key fob if you search. I don't have the link handy with me. If that doesn't work, it's likely the circuit board of the key fob needs replacing.

Edited by Ahsai
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Thank you Ahsai. :thumbup:

Your rundown is excellent, precise, and easy to follow. I will do as you recommend, and report back on this string after.

One other thing i noticed the vehicle does is this: because my fob does not work, i am forced to lock vehicle with the key manually.

When i do that, and unlock the door, if i do not start the vehicle right away the alarm goes off until i turn the key to ignition on, or start car.

Am i assuming correctly that this is the same issue as you mentioned above of resetting the key fob, or replacing the fob's circuit board?

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You're welcome and let us know what you find.


Regarding your locking problem, that's not the normal behavior. I just tried it on my '03 996. If I lock the car with the key on the driver's door, the dash red LED will start blinking (like after you use the keyfob to arm it) but the head light won't blink. When I unlock and open the door, the alarm will not go off and everything is fine and quiet.


However, our cars have a battery saving feature where if you arm the car (with the keyfob) and leave the car undisturbed for a few days, the alarm will go to deep sleep and will NOT respond to any keyfob commands after. You have to use the key to unlock the driver's door, at which point the alarm will go off and you have to insert the in the ignition to turn off the siren. But this is not what you experienced though.


If after resetting the keyfob still no go, one will have to use Durametric or Porsche scanner to further diagnose it.

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I believe it is what you mentioned earlier. The key fob's circuit board is bad, so the vehicle's alarm system has gone into deep sleep mode weeks ago, and is responding the way you described when i open the door with my key, because the fob does not work. The siren goes off within 5-10 seconds. So i have now began starting the vehicle before i get in the car. While standing outside i insert my key and start the car... It's the only way to beat the timer before the siren starts screaming away. :eek: I believe that might be the reason why Porsche has put the ignition on the left side of the dashboard; so we can start the vehicle while we are standing outside...   :thumbup:  

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Lol but my understanding is the alarm should get out of this deep sleep mode once you put the key into the ignition and this behavior should not repeat unless you again park and arm the car for an extended period of time. Without a working keyfob, you obviously can't arm the car so I can't explain why it keeps doing this.

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