The center terminal connects to the battery feed and the outer ones to the headlights (wouldn't really matter which is which). You probably have the wires switched. If the hot is connected to one of the outer terminals and high beam feed is connected to the center terminal, you'd get exactly what you're seeing. Double check your wiring at the dimmer switch.


Kevin
1951 Chevy 3100 work truck
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1929 Ford pickup restored from the ground up. | 1929 Ford Special Coupe (First car)
Busting rust since the mid-60's
If you're smart enough to take it apart, you darn well better be smart enough to put it back together.