Many electrical problems such as rear lights not working, power windows/door locks not working and mis-diagnosed fuel pump issues can be traced down to a corroded ground buss.

Here is a visual and brief description on where to locate the ground buss and how to
pull it a part, and clean it.

Take off the trim holding down your carpet next to the drivers seat (there is one in the same location passenger side)
Pull back the carpet.
You will find a large electrical conduit with a 'ground buss' taped to it on the out side.


Very carefully cut the tape and pull the ground buss from the conduit.




Now with a small flat screw driver pop off the cover of the ground bus.
Pull the metal buss out of the connector.




Inspect for corrosion and clean with fine steel wool.
Apply dielectric grease on both sides to protect it from future corrosion.
Also make sure you clean off any corrosion found in/on the wire connectors.

Example of corrosion on the buss:


Example of corrosion on back of wires:


The reason for this corrosion is because over time our inner door moldings shrink and allow water to splash in the interior and the water seeps down on top of these two ground areas.

Personal note: mine was so bad that I ended up going to a junk yard and finding two near perfect ground buses from a newer Bonneville. I also cut enough wires to replace my ground wires going to them.