Updating headlights to the 20th century

The old mustang headlights were not Halogen and did not need much electricity or voltage for power. So Ford only gave it 8 volts. New Halogen lights require a full 12 Volts and you'll often see an old mustang with dim headlights since it had 4 volts less then needed.

There is an easy way to fix this problem. You have to install two relays, one for low beams and one for high. These relays act as switches allowing a clean 12V to the lights. The wires also have to me beafed up, from 18 guage to 12-14 gauge. So I decided to tackle this project since it seemed like an easy one and I had some spare time.

I ripped out the old headlight wires and installed new ones from two relays inside the wheel well - I have enough wires already in the engine bay from my sloppy 5.0 mess. The relay logic is explained in my 5.0 wiring harness explanation earlier.

It made a big difference. My headlights are as bright as any modern car!