Join Date: Jan 2000
Location: Maple Valley, WA, USA
I checked my wiring diagrams for my '69 last night. Your's may be different, but I'll give you my info in case they're the same or similar.
Wiring to high and low beam lamps come from the dash, independently, via the forward lighting harness. Both come from the hi/low switch. The color of the low beam power wire is Teal (#16). Since none of your low beam lamps work, I would suspect that there could be a loose or broken wire somewhere between the switch and the first lamp. It could be at the lamp, at the bulkhead connector or at the switch. It is at the switch where the power for both low and high beam lamps have a common source (headlight switch). Since your high beam lamps work, grounding should not be the problem. Both high and low lamps share a ground.
Of cource another possible cause could be the switch itself.
To help in your troubleshooting, turn on your lights and check the voltage at the first light. If no voltage there, check the output of the switch. That should tell you if the problem is with the switch or with the wiring.
Let us know what you find.
69 SS Silver Bullet