Will not start

The description sounds like corrosion at either the terminals or the connections for the cables. The clicking points to a lack of amperage through them. The 8 seconds is due to the way the starting system works on that vehicle. When you turn the key to the start position it initiates a timer in the PCM that turns on the starter relay for that time. Normally the engine will start faster than that time and once the PCM senses the rpm rise it shuts off the relay.
However, how do you know the battery is fully charged? Was it load tested for voltage and amperage output? I don't think the issue is in the harness however, that isn't a common failure point on them.