Amplifier ground location rear cargo area 2018 edge

[Sledwrecker]

Can someone advise a good ground location in the rear cargo area to ground a 500w rms amplifier.  Using 6ga copper wire high quality.  I drilled a hole in one of the rear seat brackets and affixed there but I don’t think this is suitable as I’m troubleshooting low output and have isolated the issue to either a bad ground or pre amp voltage.  Any advise would be greatly appreciated.

 

2018 edge titanium with pac ad4-fd21 module for pre outs on Sony premium sound system. 

[Sledwrecker]

Definitely grounding to the seat brackets or bolts won’t work.  Just did a DMM test and resistance is .27. For comparison resistance directly to a factory ground is .02.   Any advice on a good ground would be appreciated.  I’m reluctant to drill into the floor pan as it’s unclear what’s underneath.   If there’s a factory ground behind one of the rear inner quarter panels please advise how to remove them safely without breaking anything.

 

[Sledwrecker]

A quick final follow-up to this thread.  I ended up using a factory ground location behind the drivers side rear cargo area inside quarter panel.  It's in the same location the factory sony amp is grounded to.  I did not use the exact same ground as the sony amp, there was a second hole already pre-drilled in the metal I sanded down and used a bolt and nut to ground to.  When testing this location I got a resistance value of .003 which was almost as good as testing directly to the negative battery ground under the hood.   

 

It's actually very easy to get to this location. 

1. Using a trim removal tool pop the two plastic rivets out of the trunk plastic scuff trim where the latch is on the bumper. 

2. Gently pull out and up to remove the trim piece. 

3. Next pull back the weather stripping running around the rear bumper and the drivers side up to the top of the panel.  once the weather stripping is pulled back you will have a gap between the panel and the body. 

4. Firmly grasp the panel and pull it straight and firm towards the inside of the car (straight away from the body.)  It's held in with multiple clips only, no screws.  I didn't bother pulling it off completely..  I pulled it away about 1 foot in the rear to give me enough room to work behind it.   

5. Your ground locations are behind a small area of fireproof insulation material. 

6. I removed the two plastic rivets holding the material in place to get clear access to the ground holes.  You will clearly see where the factory grounds are at once you move the insulation.   

7. Sand your ground spot well then reverse steps to close everything back up.

Edited June 8, 2020 by Sledwrecker