Minok

Seen there were many threads related to this sort of symptom in the past years, though I'm not sure this case is like them, but may have missed something.

Its a 2009 997.2 and it sat on the battery maintainer much of the past year, as much of the covid era. But age also wears out parts so now 14 years into its life, as it was having a hard time cranking up, I figured its time for its 3rd battery (so the prior 2 batteries had average 7 years per battery).

Simple job, what could go wrong, done it before. Put the car on the battery maintainer (12 v cig power port in the center by the hand brake).
Unbolt the battery cables, insulate their ends and push them out of the way, unbolt the hold down, tilt and remove the old battery, put the new one (an AGM this time) in the slot, reinstall the hold down clamp. And reattach the power leads first the positive to its post, then the negative to its post. Tuck away the now unneeded off-gas vent hose.

Now the fun, get in and insert the key - radio comes on as usual, the dash display illumination of mileage, displays, the PCM is running. The power seats work.

But that is it. Insert the key, and turn to engage the electrics and nothing happens - nothing additional lights up in that position. At all. Note, I'm not trying to start the car here, just the ACC power position doesn't get anything lighting up beyond the basics. Turn the key to start (clutch depressed and nothing happens, of course). As there was no prior indication of an issue and the car has been sitting in a mild weather area in a garage, I've got no reason to think there is a mechanical switch issue such as with the keyway being grunged up or the clutch switch now being a problem.

The turning of the key from off to the next position, which should power up the car's electrical systems just doesn't do anything.

So what have I managed to hose up?

And what should I do to address it? Disconnect the battery for an hour and reattach?

ADias

Disconnect the battery AND the maintainer, wait a few minutes. Reconnect the battery and try.

joes c4 cab

Maybe try resynchronizing the key?

Wayne Smith

I was out with a group of friends some years back. Some how keys got flip flopped. Same symptoms that you describe. Do you have a key for another car?

OK, not likely. As already suggested, try syncing the key.

Maybe you're in sleep mode. Lock and unlock the driver's door with the key.

TomiK

Does it make the loud click as you insert it (steering lock)? If not, I've had that happen intermittently when I just got the car. It was a garage queen. I've been driving it a lot recently and it hasn't happened lately.

I suspect the internal copper 'switch' inside the ignition module is stuck, possibly from sitting unused. There are images on this site showing the internals of the ignition. Apparently quite easy to dismantle the module and clean the contacts.

Hope this helps.

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Petza914

Check the other side of the battery negative ground. If it was loose or corroded, when you moved it out of the way to remove the old battery and install the new one, maybe if that connection was loose, it's now not making good contact.

workhurts

Try it again without the maintainer. Also test the new battery itself.

roccocaiazza

Lock the car with the key fob. Then unlock.

Minok

That seemed to work just fine and was not the issue. The enabling of the accessory power / ignition position was the only issue.

Minok

Brilliant - that did it. Legend.

Well, as it was late at night I just disconnected the negative terminal from the battery, tucked it away by the side and went to bed - not wanting to wake neighbors in case there was horn wailing on a reconnect.
Next morning, reconnected the negative and the car is all back to normal. The module for that accessory bus enable just did not like being on the battery maintainer at all.

997.2GTS

There's a good reason for the accessory bus not liking the battery maintainer, as it's just that - a maintainer, not a power supply. The CTEK and other new tenders charge the battery in 'pulses' pretty much the whole time, rather than a continuous voltage. Asking one to be the backup power supply to sensitive electronics that are no longer buffered by a battery is asking for trouble, IMO.