I can locate only two grommets in my '05 Odyssey firewall. The main one is on the far top left of the firewall (looking towards the rear of the vehicle) - its a thick bundle of wires in a large grommet. The other is a small grommet near the gas pedal that the heater valve actuator cable goes thru.

Ideally, I'd like to find an unoccupied one near the gas pedal, but at first look it looks like there are no more. I'm planning on running a 10awg twisted pair cable to the battery terminals for power for my CB radio, and I'd rather not make the cable any longer than need be - the top-left grommet route will add maybe 6ft.

Are there any hidden from view - like under the carpet? Or are these the only two?

 

It looks like there may be two 30mm blind plugs (part 14):



http://www.sonshondaparts.com/...dIrno=