Wiring Fuse Box

[Jdk843]

Hello this is my first electrical fix on a vehicle. I am not worried about doing it I just am not sure what I need when I get into it. 

 

2005 Chevy Silverado 4.8l 2wd

 

First the wire harness itself. What size wiring would be in there? Then all the wiring in the bottom of the fuse box and pins I want to possibly replace some if not all. I am definitely having some electrical issues and I've narrowed the problem down to harness into the fuse box, as well as a few pins on the fusebox so I'm wanting to fix that.

 

If anyone knows sizing of wires and what else I might need that'd be great

[Formulabruce]

Before you go crazy, fix the harness ground wires on the back side of the Drivers side CAB MOUNT EXTENSION. Just under the drivers door and faces the rear of truck. A bundle of wires is grounded there.  Good luck

[Jdk843]

On 2019-03-12 at 12:30 PM, Formulabruce said:

Before you go crazy, fix the harness ground wires on the back side of the Drivers side CAB MOUNT EXTENSION. Just under the drivers door and faces the rear of truck. A bundle of wires is grounded there.  Good luck

You believe I may have destroyed that ground? I mean it makes sense given the age and my issue. It's quite obvious a fault on one simple wire.