Disconnecting battery on a 996... - Page 2 - 911/Carrera GT - PistonHeads UK

Before I do, anything I need to be aware of? i.e. any problems I'm likely to encounter when I reconnect? I have the stereo/Nav codes, so should be OK there. Anything else? (presumably closing the front boot would be a bad idea whilst it's out )

Hi, make sure ignition is turned on or else alarm siren will go off! If before 2002 you will need the radio code.

don't need ign. on just first click. Reconnect needs nothing

What a coincidence. I have just come in from disconnecting the battery on my 996. The radio had stuck on, but no music playing, even with car locked I could see it still had a dim light on it. Owners manual makes no mention of ignition key. Low and behold I set the alarm off. The neighbours must love me. I kept pressing the key fob and it wouldn't turn off. Desperate to shut it up I put the key in the ignition and turned it one click and peace was resumed. Flipping window stopped dropping temporarily when I shut the door, but after a few seconds that sorted itself out. Radio has now reset itself and working again. So yes, make sure you turn the ignition key before disconnecting!

monthefish said: Before I do, anything I need to be aware of? i.e. any problems I'm likely to encounter when I reconnect? I have the stereo/Nav codes, so should be OK there. Anything else? (presumably closing the front boot would be a bad idea whilst it's out ) Petrol gauge goes to zero if tank less than half full. Trip meter to zero.

Thanks guys - I'll leave the ingition on at the first click. Daft question - what powers the alarm when there's no battery?

monthefish said: Thanks guys - I'll leave the ingition on at the first click. Daft question - what powers the alarm when there's no battery? It has a built in backup battery.

monthefish said: Thanks guys - I'll leave the ingition on at the first click. Daft question - what powers the alarm when there's no battery? the alarm will have a battery/capacitor to power the alarm for a short while else people would be disabling the alarms by cutting the power

I recently did this and followed the advice provided. It's super easy. The siren for the alarm is positioned next to the battery. So you really want to turn the ignition one notch, as if you don't you have one hell of a deathly noise directly in your ear whilst changing the battery !

Indeed, it was flipping painful, having that siren in my lughole. I was a bit confused that it was so loud without being connected to the battery. Makes sense now.

monthefish said: Before I do, anything I need to be aware of? i.e. any problems I'm likely to encounter when I reconnect? I have the stereo/Nav codes, so should be OK there. Anything else? (presumably closing the front boot would be a bad idea whilst it's out ) Probably repeating but if the car has the M536 option with the alarm siren next to the battery turn the ignition key to the on position before disconnecting the battery. Be sure all other electrical loads: radio, stereo, lights, NAV unit, switched off. Never attempt to start engine with battery disconnected. Do not attempt to use charger to start engine. When reconnecting battery you have to: Reset the window limits. Consult your owners manual for instructions. For my cars press and hold the lower window button until the window is all the way down. Then release and press the up button and hold it until the window is all the way up. Hold for 5 seconds. Repeat these steps for the other side. Recalibrate the e-Gas system. Consult your owners manual, but IIRC with the key off and your foot off the gas pedal, turn the key to the on position. Leave in the on position 60 seconds. Do not press the gas pedal. Do not attempt to start the engine. Do not switch the key off. After 60 seconds turn the key to the off position for 10 seconds. Then you can start the engine. Depending upon the fuel level the fuel level display can be wrong. (This for those models that have AWD and the fuel tank is special.) Fill the fuel tank.

I find it utter madness that you have to do all these things. Would be nice if Porsche engineered it to do all that once the battery was reconnected. Fair enough about turning the key in the ignition to stop the alarm sounding - makes sense from a security point of view.

JackieTreehorn said: I find it utter madness that you have to do all these things. Would be nice if Porsche engineered it to do all that once the battery was reconnected. Fair enough about turning the key in the ignition to stop the alarm sounding - makes sense from a security point of view. Thats because you haven't seen the more recent BMW's... on those you need to visit the dealer very time the battery is disconnected to reset the system...

JackieTreehorn said: I find it utter madness that you have to do all these things. Would be nice if Porsche engineered it to do all that once the battery was reconnected. Fair enough about turning the key in the ignition to stop the alarm sounding - makes sense from a security point of view. The fault lies in owners thinking they are dealing with a farm tractor or piece of lawn machinery rather than a highly sophisticated and modern sports car. If you are not prepared to do the battery R&R right then you have no business complaining. Since Jan 02 when I bought my first Porsche I've only had to disconnect the battery once in order to remove a dead battery and replace it with a new one. Since then I have had 2 other batteries need replacing but in both cases I took the car to the dealer and the tech first connects back up power to the car's electrical system, removes the old battery, installs/connects the new battery and then removes the back up power. No radio codes to fuss with. No window limit resets. No e-gas fiddling. In short no muss, no fuss.

Rockster said: The fault lies in owners thinking they are dealing with a farm tractor or piece of lawn machinery rather than a highly sophisticated and modern sports car. If you are not prepared to do the battery R&R right then you have no business complaining. Since Jan 02 when I bought my first Porsche I've only had to disconnect the battery once in order to remove a dead battery and replace it with a new one. Since then I have had 2 other batteries need replacing but in both cases I took the car to the dealer and the tech first connects back up power to the car's electrical system, removes the old battery, installs/connects the new battery and then removes the back up power. No radio codes to fuss with. No window limit resets. No e-gas fiddling. In short no muss, no fuss. Great tip Rockster

Brilliant. Well done.

Thanks for all the advice. New battery fitted - no problems encountered.

I am right in thinking, following the second post above, that as my 996 is a late 2003 model I do not have to re-set the radio code after disconnecting the battery? Hilux

7 year old but still handy advice. New battery being delivered this week. Wonder if my 996 can go down as a covid stat.

Just make sure it goes in the right way round - I’ve read several horror stories of people connecting +ve cable to -ve battery post and it kills all sorts of electronics. I think its confusing as both cables are black. Easy sense check the earth cable is bolted directly to the body. Ian

Before I swap the battery over, how do I find radio codes? Car is 2000 C4

Usually in the handbook / user manual bumph - perhaps on a business card in the leather wallet? Mines a 2003 so no code needed. Ian

Well that was easier than I thought, bear in mind I am no way mechanical. Car is running so much better, maybe a placebo affect but I like it. Feels brand new.

F*CK ME THE ALARM IS LOUD!!!! Wish I found this thread before I took that bloody battery clamp off!!

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Another shout out for this excellent thread… refreshing my memory as I change the battery on my 4S. Happily the last one died with 6 months remaining on its 5 yr warranty.