Weird Headlight Problem

[DougC10]

Hello, everyone!

I have a 1986 C10 Silverado 1500.

When I purchased the truck, I knew the headlights needed work.

When turning on the headlight switch, the top driver's side lamp turns on, but not the passenger side. When hitting the dimmer switch on the column, the driver's side top lamp stayed on and the passenger side lower bulb turned on.

First troubleshooting step, I replaced the lamps in case of defect. At this time, when turning on the headlight switch, the driver's side top lamp turned on, but no other lamps. When hitting the dimmer switch on the column ALL FOUR lamps were off.

I assumed this meant either a bad ground or wire in the harness.

My next step was to clean the ground connections with a drill and wire brush, replace a damaged ground from the harness. I installed the heavy duty headlight harness from LMC truck.

After installation, the behavior returned to what I initially had (turning on the headlight switch, the top driver's side lamp turns on, but not the passenger side. When hitting the dimmer switch on the column, the driver's side top lamp stayed on and the passenger side lower bulb turned on).

This afternoon after work, I will replace the headlight switch but am not feeling confident. I think this will require pulling down the steering column to replace the dimmer switch.

Is there another possible solution that might not be as hard as that?

You must be registered for see images attach

 

[Ricko1966]

I seriously doubt it's either switch. And before I replaced one even if I suspected it I'd test it. Where I'd start is unplug all 4 headlights. With a multimeter check each headlight socket for ground.(in ohms mode ground 1 lead of your meter,touch the cavities in the headlIght socket with the other) each socket should have 1 socket that should make your meter read 0.00 ohms to 0.2 ohms. After that in volts mode again 1 lead grounded headlights on low position check your top 2 headlight sockets,should be 1 terminal in each reads close to battery voltage( check battery voltage with the meter) in high position check for 1 hot terminal at each socket. Post results. Just thought what I'd do before that. Park facing a wall,look at the wall while wiggling all the under hood wiring,watch for flickers on the wall.