I can't recall for sure, but I think the 69 has 2 ground wires from the battery, one to the block and one to the inner fender. Check the ground to the inner fender -- this is the one that all the accessories use. Once upon a time in my then girlfirend's 72 Nova, this wire had corroded while still looking good on the outside. The headlights would glow dimly until you pressed in the clutch!?

regards,
Leon