Hi guys. I just picked up a 1990 240 DL wagon. Previous owner said style headlights stopped working very recently. Intermittent for a couple days then to stopped working altogether.
Here's where I'm at with it.
Step relay-audible clicks.
Headlight relay-audible clicks.
Dash lights work
Parking lights work
Brake lights work
Indicators work
No low beams
No high beams
New bulbs.
Integrity sensor looks good but smells a little funny
I haven't gone ground hunting yet. I did pop the cover off the integrity sensor. Everything looks good inside, nothing melted or toasted. Not sure where to go next other than checking grounds, and trying a bulb sensor. Thanks! Any help is much appreciated!

 

Figured it out! Step relay is old and getting stuck. Stick clicks but doesn't actuate like it should. Rigging it to stay on low beams until I get a replacement.

 

fwiw, the bulb sensor might go wonky and indicate that bulbs are bad when they aren't, but its pretty unlikely to CAUSE a bulb not to work.

frankly on older cars, they become a pain, flickering on and off due to slight oxidation on the tail lights, that sort of thing, I'd be very inclined to bypass it. most of the circuits in it have 1 input and 2 outputs, you simply wire these together. I'd probably use an old one for the plug and gut it, and wire the jumpers inside it.