Having owned a 245 diesel and two 245 gas models, plus my current 745, I am well used to flaky Volvo electrical problems. This one has me stumped. When I turn on the headlight switch, with the ignition on, the parking and panel lights come on, but sometimes not the headlights. Pulling up the flasher switch turns them on an lights the high beam lamp, but only repeatedly turning the main switch will get the headlights working.
I have changed:
The bulb sensor
The main lighting relay
The headlight switch itself.

I have checked and cleaned:
Fuses
Grounding points on inner fenders

Still have the problem.
Is there another relay for the headlights somewhere. Any other ideas?
When I do coax the lights to work, they will remain on until I shut off the ignition. Sometikmes they will work for several weeks before getting flaky again.
In the dark.