94 suburban headlight woes

I'm having some headlight problems. The low beams work fine but when I try to switch on the high beams, all the headlights go out. Kinda scary when you're riding down a country road at night. It happened intermittently at first and now all I can use is the low beams. I've got the steering wheel off and the instrument cluster cover out of the way to work on any switches. Sometimes I have to wiggle the headlight switch to get my dash lights to come on. Any ideas on what could be causing the headlight problem?

I'm having some headlight problems. The low beams work fine but when I try to switch on the high beams, all the headlights go out. Kinda scary when you're riding down a country road at night. It happened intermittently at first and now all I can use is the low beams. I've got the steering wheel off and the instrument cluster cover out of the way to work on any switches. Sometimes I have to wiggle the headlight switch to get my dash lights to come on. Any ideas on what could be causing the headlight problem?

what is needed is a meter to measure the voltage at the headlights..your vehicle I believe has the rectangle shaped headlights..

the socket and the pins get corroded, there may also be bad high beam filament ...

If one headlamp is bad you must replace both as they do work together...placing dielectric grease on the bulb connections help keep the corrosion under control...............

your interior lamps are a separate circuit this would be the dimmer resistor which is part of the headlamp switch...if you dim the interior lamps too much this causes this to fail, as the resistor/dimmer gets very hot ..

It was the dimmer switch. Thanks