Had a very similar experience to that described by 'Mike Collins'.
Car was a Volvo 480ES with daylight/ sidelight twin filament bulbs and
pop-up headlights.
Problem was that the pop-up headlamps wouldn't work. Haynes wiring
diagram was as much use as a chocolate fireguard, so armed with a multi-
meter and some pins, I worked out my own circuit diagram.
Took bloody days
Anyway, worked out in the end that the reason my headlights were not popping up
was the sidelight/ daylight twin filament bulb. The circuits interlinked through relays,
one circuit providing an earth return for one relay which when made provided a positive
feed for another relay.
The first time the cause, same as 'Mike Collins', was the daylight filament busting and
joining with the sidelight filament. Thus the 'daylight circuit was permanently live meaning
that the relay for the headlamp actuators wouldn't energise. Result...... no headlamps!
Second time, the 2 connections on the bulb holder had weakened, with repeated bulb changes
and heat from a working circuit, and were touching when the bulb was sprung into position. They
looked normal with the bulb removed.
So check your bulb, the holder, cable connections, and what relays you have in this system.
Haven't checked out my Omega system yet, due, so far, touch wood, no problems.
Whenever I start to look at the Haynes circuit diagram, my eyes start to glaze over and
I get this strange urge to fall asleep.
Car electrics can give very strange results with just a small fault. Ask anyone who has played
with towbar electrics and the weird results they start getting when you start adding
different power and earth circuits. No wonder they're all bald.
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