Replace the headlight switch.
1992 Ford Thunderbird
Electrical / Lighting Systems Malfunction When driving When warm
Q: The headlights begin to flicker after they have been on for a while. Is there a solution for this?
A: Most of the Fords have a breaker as part of the headlight switch assembly.... it is a circuit breaker and it gets weak after years of use.... A new headlight switch should fix this problem for you.... Ed