I have a 1991 e250 / 5.8 motorhome. Lights come on, but when I hit the floor dimmer switch to get high beam lights, all lights turn off.
I replaced the floor dimmer switch, but that did not work.
Appreciate some help please.
Thank you .
Mem

 

You could do two things,
Get a hold of a test lite , remove one of the headlamp plugs and see if the test light lites when you have the high beam on and you probe the headlight plug. If it lites , that sealed beam is in need of replacement.
The other thing, you could simply replace one of the sealed beams and see what you get. It is possible both lamps are blownout.
If those two don't work now you need to start at the dimmer switch and make sure the switch is working . If it is, then you will need to go under the hood and start tracing back on the hi beam wire looking for a break or poor connection.
Did you replace the dimmer switch because you had no hi beams? When you say all lights turn off some or all ?

 

Thank you for the reply, appreciate it.
I replaced the dimmer switch, because I thought to start there to see if that was the problem, but it is not.
So will replace the headlights and check that, if not will go from there....
my headlights go out and total dark when I drive and hit the high beam dimmer switch.
Will check and see the other lights.

 

Get a hold of a test lite , remove one of the headlamp plugs and see if the test light lites when you have the high beam on and you probe the headlight plug. If it lites , that sealed beam is in need of replacement

That was it, took a wire and hooked up battery to light and high beam worked...
So I guess it is the sealed beam ........
Thank you for the help
Mem