We have the headlight switch set to "daytime driving lights" on Arabella, our 1996 850 sedan. I recently noticed that the headlights aren't on in either daytime driving or full-on lights ("night time") settings. Side and rear lights go on in full lights setting. Headlights will flash if I hold the turn signal switch back - the daytime "flash lights" function - but the low beam/high beam relay isn't cycling when full lights are on.

Since the each beam of each headlight is separately fused, and since the "flash lights" function works, I suspect the headlight switch. Before I spend $50 on a switch, is there anything else I should be examining?

I think there was a recall on 850 headlight switches. You might check with your dealer.
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'96 855R,'64 PV544 driver, '67 P1800 basket case, '95 855, '95 854, the first three are mine, heh, heh, 435,000 miles put on 9 bricks

Thanks for the suggestion, James, but the dealer says no record of a recall in that year.

Waiting for the part to arrive - thank goodness it's a quick install.

After about an hour of tracing out the rather sketchy wiring diagram in my Haynes manual, and 45 minutes of testing the switch and the circuits, I determined that the headlight switch is defective - for mechanical reasons. The headlight switch is in two parts: a) a faceplate that carries the knob and b) the switch circuitry in a block that is held behind the face plate by tabs that snap into cross-wise slots (behind all that is the wire connector). The cross-wise slots at the bottom had broken out, and the circuit block was swinging free, and failing to make contact. This I did not discover until I'd ordered a replacement switch (eEuroparts, less than half the local discount auto parts store), but that's OK; I'd rather not depend on the duct tape currently jury-rigging the switch together.

Some notes:

1. The headlight circuit is insanely complex. As best I can tell, there are three relays to operate it, in what locations I don't know, so I'm glad that it was the switch (especially since those plug-in relays are really hard to test).
2. One of those relays turns on power to the headlights when the switch connects terminals 7 and 9. I determined that the problem was the switch when I was able to jumper across those two terminals and get lights, but testing the corresponding terminals on the switch did not show continuity, until I taped the switch together (feeling like a fool when I finally realized what had been screaming at me from the time I took the switch out and noticed it was kind of floppy).
3. The switch uses small-dimension male spade terminals going into spring-loaded female receivers in the connector. I didn't have any male spade terminals of that small dimension, so I cut strips of galvanized flashing, pushed them into the connector, and jumpered across them with a wire with alligator clips. Pieces of unpainted tin can would probably have worked as well, but I had the flashing.
4. As I mentioned, at the moment, the headlight switch is held together with duct tape. Not the plastic stuff, but a metallic tape that's the modern version. Very strong, very sticky, and would probably last another 50,000 miles; I may save the headlight switch when I replace it with the new one, as a spare.
5. The manual describes removing the switch (indeed, all the instrument panel switches) by prying at it with a little screwdriver. This is more than kind of a pain. I took a couple of pieces of the flashing about 1/2" wide and about 2" long, bent a sharp right angle on one end by doing a rough bend first, then clamping the length in the vise with the bent part at the jaw and hammering it to a sharp bend, and filed the resulting "finger" very short. So far, this seems to work better - I push the sheet metal back to catch the back lip of the front part of the switch and pull.

Another thing you might want to check is right behind the drivers side headlight under the hood is the connector from the engine wiring harness to the headlights. It's a silver locking pressure type bar that locks the two connectors together. It's possible that the connection has come loose.

i have seen used/working headlamp switches for 850's go for less than $10 on eBay.

...and from what you describe in your post you should check that your bulbs arent dead before replacing the switch.
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-woodsytf '95 850 wagon 157k

Hve you verified that the headlights haven't burned out? There are separate bulbs for high/low.
With a bulb removed (do not touch the glass with bare fingers), turn the headlights on and check for voltage. Or check the bulb itself for continuity.

BTW, pos 0 of the headlight switch is not the DRL switch. The DRL switch is that fake looking screw in the switch assembly.

Klaus
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The 164 has a new home, all I am left with are a 95 854T and a 98 V70R :)