Or "earth" as the Brits would say

It's bizarre, I had everything working fine 'till the subs cut out the other day and I started going down the list of possible problems. The "fault" led would turn on when they tried to power up.

After messing around for a while, I finally just checked voltage from my battery cable to my ground wire.

3.5V?!

Okay so I "poked" around for another ground, I found some random little screw and sure enough I got ~12V.

I had been using the freaking 7th passenger lower seatbelt bolt as a ground point, since it's a massive bolt and (at least I thought) it would go directly into the frame?

Obviously it's connected through some other structure which isn't directly connected to the rest of the frame's grounding points/straps. I'm not sure why it randomly decided to die on me, but whatever.

Should I just cut out a square of carpet in a semi-hidden location and use two large-gauge machine screws? The amps aren't that large (250RMS 800 peak x2) so that might work. I can't see any other bolts back there which I could use, unless there's something under the carpets.

 

Mine is grounded underneath the seat. Where the seat clips into when down, there is already a hole in the carpet there, and I just put it on one of the bolts connecting directly to the floor. I have had no problems.

 

take a wire brush and scratch some metal surface, it doesn't matter where but be careful what is on the other side (I would check for the gas tank and the visible outside of the vehicle) then using a self tapping screw and a ring terminal make a new ground, a general rule of thumb is less than 2' is the best for an audio ground but no more than 3' will be ok

you shouldn't need to cut the carpet, just pull it back. you may need to remove a panel if it is tucked underneath

also a star washer will help give a little extra bite, some people seal the screw from underneath but you don't really need to

 

I hope this is of some help, with the cap on the back of the seat, I can not fold down the seat without first disconnecting everything. However if you want, I can disconnect it and get some pictures of where is it.

 

Sorry the pictures didn't post the first time.