driving down the road and my headlights went out, dash and parking lights still on, everything working ok but headlights, they came back on after about 45 sec. is there a relay or a time fuse?
1983 z/28.

It's the circuit breaker inside the headlight switch itself; it's overheating from too much current running through it, and 'kicked out'. Once it cooled down, it reset itself.
If you've recently switched to a higher-output headlight, those could be the culprits, as could any corrosion or dirt on the connector contacts of the headlights.
A great solution to the problem of higher-output lights can be found here.

Pete

thanks pete I did put in new cool blue headlights, and I read the site you gave. guss I will have to go back to the old lights or build a new harness.