Headlights not working

[Jim18655]

2000 Adventurer 35U.
All 4 headlights come on with high beams. When I turn off the high beams nothing is on. All clearance lights, tail lights and turn signals work with headlight switch on.
Connectors on switch look OK.
Any ideas where to look?

 

[Isaac-1]

What chassis is it on?

 

[Jim18655]

F53, I forgot it could be a Chevy.
All fuses are good, swapped relays around. Can't remember if it has daytime running lights. If it does they're also out.

 

[John Canfield]

One culprit is the multifunction switch (headlight stalk) which can cause some very strange issues. Also check grounds and that all running lights are working.

 

[Jim18655]

Actually turned out to be 2 burned out lamps.
I feel pretty stupid for going the hard route troubleshooting and over looking the obvious. I never would have thought both lamps went out at the same time. Probably didn't, I just noticed them being out at the same time. Never gets driven at night so I wouldn't have noticed just losing 1 of them.
40 years of electrical troubleshooting and I overlooked the easy test.

 

[Mark_K5LXP]

Many moons ago I got caught by a similar issue. Tore into it looking for a melted/shorted harness or wonky switch, ended up being a dual filament bulb where one of the filaments broke, and welded itself to the other filament. So the bulb still worked but caused all sorts of weirdness between the two circuits. You wouldn't suspect a bulb that lit up so went round and round looking at everything else.

Mark B.
Albuquerque, NM

 

[Lou Schneider]

Many moons ago I got caught by a similar issue. Tore into it looking for a melted/shorted harness or wonky switch, ended up being a dual filament bulb where one of the filaments broke, and welded itself to the other filament. So the bulb still worked but caused all sorts of weirdness between the two circuits. You wouldn't suspect a bulb that lit up so went round and round looking at everything else.

Mark B.
Albuquerque, NM

Years ago I was helping a friend troubleshoot a mystery short where both turn signal indicators on his motorhome's dash came on whenever the toad was connected and he activated a turn signal. Followed the classical path by starting at the source and isolating wires while working rearward. Turned out to be a dual filament tail light bulb in the toad where the double buttons on the bulb's base were 90 degrees off from the locator tabs so when the bulb was inserted in the socket they shorted the socket pins and created a connection between the stoplight/turn signal and the tail light/marker light circuits. He'd purchased the bulb from a swapmeet vendor in Quartzsite.

 

[John Canfield]

Actually turned out to be 2 burned out lamps.
I feel pretty stupid for going the hard route troubleshooting and over looking the obvious. I never would have thought both lamps went out at the same time. Probably didn't, I just noticed them being out at the same time. Never gets driven at night so I wouldn't have noticed just losing 1 of them.
40 years of electrical troubleshooting and I overlooked the easy test.

[...]Also check grounds and that all running lights are working.[...]
Ha! I called it!

 

[Ray-IN]

F53, I forgot it could be a Chevy.
All fuses are good, swapped relays around. Can't remember if it has daytime running lights. If it does they're also out.

F53 Ford chassis with Chevy engine???? That's some serious wrenching.