Need a good 12V feed from the ACC Switch

2005 Malibu LS (Epsylon Body) Where can I get a good 12V feed from the ACC Switch. I tried the Cig Lighter but it's live with a constant 12V feed! The Radio plug also only has a constant 12V wire and no others feed 12V when ACC is switched on.

Just trying to add an FM Modulator to the radio so I can plug my MP3 Player

The "RDO-ACC" fuse,(10 amp), should be 12v when key is in the "ACC or RUN" positions. The fuse block is located in the left dash end cap,accessible when the left door is open. The cover pops open exposing the fuse block and the fuse location legend is molded into the inside of the cover. It's a yellow wire leading to the radio harness. Careful if you're taking the power off the radio harness. Theres 2 yellow wires on the radio harness plug. The other is for the LR speaker. Make sure 10 amps can handle it. Hope this helps.

Well the modulator unit I'm installing has a 2amp fuse built in, so it should be OK! I'll check that "RDO-ACC" fuse for current only when in ACC and RUN pos and use it if it fits.

I'm provisionally running it from the Cig Lighter and even tho the modulator unit has an ON-OFF switch, I would rather use the ACC feed, I just don't want to find a dead battery one day after mistakenly leaving the unit ON for a while.

Thanks for the help DeltaP