987.1 Battery Replacement and Airbag Light
10-15-2016, 02:28 AM
#1
6th Gear
Thread Starter
987.1 Battery Replacement and Airbag Light
Hi Guys,
I recently purchased a 2008 Cayman S. The PPI uncovered a few issues, but nothing that prevented me from proceeding with the purchase.
One of the issues was that the wrong battery was installed and because it was too big, the battery clamp was missing. I obtained the correct battery and clamp, but before installing it, I wanted to research the process. With stories of radio codes and other problems that required a trip to the dealer after a simple battery replacement, it seemed that the correct procedure was to maintain power while swapping the battery.
I had an inexpensive trickle charger, so I hooked it up to the cigarette lighter while I swapped batteries. After replacement I had the airbag warning light. I had also purchased a Durametric cable when I was looking for cars to purchase, so I was able to hook it up and see that the code I was getting was 8055 AWS-LIN "no communication". Researching this code, it looked like I might need that trip to the Porsche dealer to calibrate the AWS. I also came across some posts that claimed no problems replacing batteries without maintaining power and others that claimed disconnecting the battery cleared the airbag light. With nothing to lose at this point, I decided to try disconnecting the battery. To my relief it cleared the airbag light.
My goal in posting this is simply to confirm that on the 987.1s there is no need to maintain power during a battery swap. In addition, trying to maintain power with a source that is not up to the task can actually do more harm than good. In retrospect, I believe the trickle charger I used suffered a brown-out and caused at least one of the microprocessors in the car's systems to locked up. Disconnecting the battery caused all the processors to "re-boot". There are no radio codes (at least on my CDR-24) and while there are some side effects (DME needs to re-learn some parameters and emissions ready indicators are reset), it is completely safe to just disconnect the old battery and install the new one. If you do want to maintain power during the swap, make sure you use a source that can handle the load - my trickle charger cannot. I hope this helps those, that like me, are still getting to know their cars...
I recently purchased a 2008 Cayman S. The PPI uncovered a few issues, but nothing that prevented me from proceeding with the purchase.
One of the issues was that the wrong battery was installed and because it was too big, the battery clamp was missing. I obtained the correct battery and clamp, but before installing it, I wanted to research the process. With stories of radio codes and other problems that required a trip to the dealer after a simple battery replacement, it seemed that the correct procedure was to maintain power while swapping the battery.
I had an inexpensive trickle charger, so I hooked it up to the cigarette lighter while I swapped batteries. After replacement I had the airbag warning light. I had also purchased a Durametric cable when I was looking for cars to purchase, so I was able to hook it up and see that the code I was getting was 8055 AWS-LIN "no communication". Researching this code, it looked like I might need that trip to the Porsche dealer to calibrate the AWS. I also came across some posts that claimed no problems replacing batteries without maintaining power and others that claimed disconnecting the battery cleared the airbag light. With nothing to lose at this point, I decided to try disconnecting the battery. To my relief it cleared the airbag light.
My goal in posting this is simply to confirm that on the 987.1s there is no need to maintain power during a battery swap. In addition, trying to maintain power with a source that is not up to the task can actually do more harm than good. In retrospect, I believe the trickle charger I used suffered a brown-out and caused at least one of the microprocessors in the car's systems to locked up. Disconnecting the battery caused all the processors to "re-boot". There are no radio codes (at least on my CDR-24) and while there are some side effects (DME needs to re-learn some parameters and emissions ready indicators are reset), it is completely safe to just disconnect the old battery and install the new one. If you do want to maintain power during the swap, make sure you use a source that can handle the load - my trickle charger cannot. I hope this helps those, that like me, are still getting to know their cars...
The following users liked this post:
voodu3 (07-26-2023)
07-21-2020, 07:11 PM
#2
Rennlist Member
Thanks for posting this. With the above info in hand, I fearlessly swapped out my 9-year-old 
battery today, for a shiny new AGM version in same exact size. Followed owners manual resets for PSM and window positions... done and dusted. Even the memory seat settings on the respective keys were completely retained. Happy I am.
Costco / Interstate battery I fitted (scroll down for AGM version): https://costco.interstatebatteries.c...398&Country=US
Cheers!
Dave
battery today, for a shiny new AGM version in same exact size. Followed owners manual resets for PSM and window positions... done and dusted. Even the memory seat settings on the respective keys were completely retained. Happy I am.Costco / Interstate battery I fitted (scroll down for AGM version): https://costco.interstatebatteries.c...398&Country=US
Cheers!
Dave
07-24-2023, 06:45 PM
#4
Instructor
Replaced the battery in my 07 Cayman in 2014 and don't recall any issues. Today I replaced it and got a PSM alert and the airbag warning light. Disconnected/reconnected the battery hoping that would clear both, but it did not. Hooked up the Durametric and cleared the fault codes. PSM alert is now gone but airbag warning persists. Maybe it will eventually go away? I dunno. 
07-24-2023, 11:22 PM
#5
Airbag light can be cleared with the Durametric.