I thought there was a copper plate like a cheese grater on the passenger firewall that contacts the closed hood and acts like a ground trigger for the light.
I thought there was a copper plate like a cheese grater on the passenger firewall that contacts the closed hood and acts like a ground trigger for the light.
The spark plug wires generate lots of Radio Frequency Interference (RFI). The cheese grater ground prevents the metal hood from being a radio antenna for that RFI. With a ground, the metal hood dampens out much of the RFI. RFI interferes with the computer, radio, stereo and GPS, and other electronic devices, and not just those in the car, but all around the car.
You can not ground a fiberglass hood and have it conduct like a steel hood. The conducting property of metal makes tin foil hats more effective at blocking alien mind control than felt fedoras. Maybe a carbon fiber hood could help block EFI, but not fiberglass.
As far as the hood light, make sure there is a power line and a separate ground wire. It will not ground through the fiberglass hood. I have not paid attention to the Mustang light, but the old trunk and hood lights often had only a power wire.