I noticed that I only have high beams (59 has dual headlights and all 4 are lit) as I have not driven the car at night for over 2 years. When I hit the dimmer switch all 4 headlights go out. First instinct was - new dimmer switch. Wrong decision as it made no difference. Tracing the wiring diagram I do not see a problem. Could the problem be in the light switch itself?
The switch could be the problem. Get a volt meter and check the power coming out as well as going in. Also check your ground connections it's not uncommon to have rust build up and cause a faulty connection.
Actually all the headlight switch does is to provide current to the dimmer switch so if it works on high it's not the switch. Run a jumper wire from a 12v source to the hot post of the dimmer switch ( headlight switch eliminated), try, then move it to the low beam wire out of the dimmer switch (dimmer sw eliminated), now use your test light at your headlight sockets and if it lights the wiring is all good. This leaves two options: ground no good or both seal beam bulbs bad.
