Running power to trunk for a subwoofer?

wrybread · Post by **wrybread** » 17 Feb 2021, 18:58

Well a Bazooka subwoofer fell in my lap, and I installed it in my trunk, taking power from the rear cig lighter for now. It sounds terrible though, very distorted. I'm hoping it's the laughably insufficient power for a sub.

Does anyone have any tips for a routing path of, say, 10 or 8 gauge wire from the battery? And think I should run a ground too or would you tap into the chassis in the trunk? If chassis, idea for where?

Post by **FlyingVolvo** » 17 Feb 2021, 19:19

I had a sub in my V70 once. Grounded on one of the bolts under the covers in the rear for the taillights. S70 should have similar covers. Power ran from the battery through the firewall hole, and underneath the inside trim between the door door sill and the carpet. They lift up and there's enough space there to stash a wire or two. Your cig lighter is definitely not going to cut it.

wrybread · Post by **wrybread** » 17 Feb 2021, 19:51

Thanks for that. Any tips on where to pass a wire through the firewall?

Post by **RickHaleParker** » 18 Feb 2021, 22:59

If you want low lost power cables cheap. Go to a self service junkyard and get the long battery cables out of a P2 V70, S80 or XC90 which has the battery mounted in the trunk. They run between the floor and the carpet. $1.50 per foot around here. While you are at it get the plastic conduit for the cables and fab them for the best fit you can.

Post by **Ocelot** » 20 Feb 2021, 09:50

wrybread wrote: ↑17 Feb 2021, 19:51 Thanks for that. Any tips on where to pass a wire through the firewall?

If you open the hood and look to the upper left corner of the engine bay, below the pressure lines of the AC, you'll see a rubber plug. You can pry that plug out and if you insert a powercable through the hole, it will appear in the passengersside below the dashboard (I think you guys call it the knee bolster?).

Post by **abscate** » 20 Feb 2021, 11:24

Ocelot wrote: ↑20 Feb 2021, 09:50
wrybread wrote: ↑17 Feb 2021, 19:51 Thanks for that. Any tips on where to pass a wire through the firewall?
If you open the hood and look to the upper left corner of the engine bay, below the pressure lines of the AC, you'll see a rubber plug. You can pry that plug out and if you insert a powercable through the hole, it will appear in the passengersside below the dashboard (I think you guys call it the knee bolster?).

Links of rechts?

Bedankt.....

Stu70 · Post by **Stu70** » 20 Feb 2021, 12:02

“You can pry that plug out and if you insert a powercable through the hole...”

Smokey the bear says:-

Please pass any cables THROUGH the rubber bungs or plugs, never run a cable through an unprotected hole in the fire wall or you’ll have just that - a wall ‘o fire . This also means a fuse at the battery not just a fuse at the amp.

Also be careful with some packaged ‘amp wiring kits’. They sometimes have an impressive looking big 30amp fuse but woefully under size cable buried under lots of red insulation to bulk the cables appearance.

The fuse at the battery is there to protect the cable.
The amp/sub should have its own fuse to protect itself.

Post by **RickHaleParker** » 20 Feb 2021, 14:52

Ocelot wrote: ↑20 Feb 2021, 09:50 You can pry that plug out and if you insert a powercable through the hole, it will appear in the passengers side below the dashboard

Don not pry the plug out. Cut an X in the center. Push the cable through. That way the rubber plug will keep the cable insulation from rubbing in the sheet metal, cutting the insulation and shorting out. Guy have burnt their vehicles to the ground by removing the plug instead of using the plug as an insulator.

After your done with the install. Dope the plug with RTV to make it watertight again.

Post by **Ocelot** » 22 Feb 2021, 10:01

Stu70 wrote: ↑20 Feb 2021, 12:02 “You can pry that plug out and if you insert a powercable through the hole...”

Smokey the bear says:-

Please pass any cables THROUGH the rubber bungs or plugs, never run a cable through an unprotected hole in the fire wall or you’ll have just that - a wall ‘o fire . This also means a fuse at the battery not just a fuse at the amp.

Also be careful with some packaged ‘amp wiring kits’. They sometimes have an impressive looking big 30amp fuse but woefully under size cable buried under lots of red insulation to bulk the cables appearance.

The fuse at the battery is there to protect the cable.
The amp/sub should have its own fuse to protect itself.

Thanks Smokey

Forgive me for my incomplete instructions. I meant to say to PASS the powercable through the rubber plug, but if it's a thin cable that might get a bit tricky to get the cable into the car with the plug in place. My bad!