Headlight Delay
 

Here's one that has me puzzled. On my 84 CD, when I first turn on the headlights, there is a short, variable length delay.

If the temps are normal (above 50* F or so) it is only a 1/2 second to maybe a 1 second delay.

When it is cold out (low 20's to freezing) it is longer - as much as 3 or 4 seconds.

Now what the heck could be causing that? A relay getting old and sticky maybe?

Tell me they didn't put some kind of bizzare vaccum-operated component in the headlight circuit too!

Sounds like worn or dirty contacts in the switch to me.

Stop using compact fluorescent bulbs in place of headlights!

But seriously, it *does* kind of sound like dirty contacts or a sticky headlight relay. Easy(?) way to find out would be to take the relays inside with you at night, and stick them in the car in the morning. Turn the headlights on, and see if it makes any difference. Might be a bit of a PITA to do, so it's up to you. The cold can make some really funky things happen with these cars, that's for sure.

There is no relay for the headlights on a W123, they are driven right off the switch.

Whoops. I forgot that I had upgraded the headlight bulbs in my car, and stuck relays in so that I didn't fry the OEM wiring. It's been a long week. :)

There is probably some kind of conductive grease in the switch. Cold weather would make it stiff.

That is it EXACTLY. It is as if there were something that has to warm up a little before they come on, and the colder it is the longer it takes.

The really odd thing is that it is so consistent. It ALWAYS takes them at least a little time before they come on - they never come on instantly like you would expect them to (at least occasionally) if something were loose or corroded. And the delay is always longer the colder it gets - they never come on after 1 second if the temp is below 30*. The marker lights all come on instantly, so I just don't "get" what could be causing the headlights to delay.

Really weird...

Does the car start ok? Aside from the combination switch being sticky, the only thing I can think of would be a voltage issue from either the battery or alternator. It's a shot in the dark (no pun intended), but it might be worth taking a meter to it when you get the chance.

If the voltage was low, you'd notice it when starting.

Really sounds like you've got a corrosion issue, likely a ground problem.
You've got some sleuthing to do with a voltmeter. Start checking the resistance of various circuits.

Jim

Starts BEAUTIFULLY! Even with the temps down in the 'teens recently. I wait until the glowplug light goes out and turn the key and it fires off before it can complete two full revolutions.

Battery is fairly new, and the alternator is doing fine at keeping it charged up. Most of my driving (to and from work) has been in the dark for the last couple of months, so I think it is pretty safe to say the alternator is keeping up with all the loads - including the headlights. They aren't dim or anything. No flickering or fluttering when things like the heater, radio, turn signals, or rear defroster get turned off or on.

No other symptoms - just the delay of the lights coming on.

Headlight switch knob not engaging the switch "axle" properly perhaps? Is it nice and tight in the headlight switch?

Yup, sure is. Nice solid click-click as it rotates through the Parking Lights and then to the Head Lights position.

1) When you use the "flash" on the combination switch........is there any delay?

2) When you switch the combination switch to the high beams and start the process again.........is there any delay on the high beams?

Neither - at least not that I've noticed. I'll try it to double-check on the way to work tomorrow...

OK, I checked the high beam functions - both functions (switching to high beams and "flashing" the high beams) work normally - no delay.

I also turned them off and back on about a half dozen times in the first couple of miles/minutes of driving. The longer they are on, the shorter the delay for them to come back on when switched off then back on. After a few minutes of being continuously on, they get to where the delay is miniscule - less than a quarter of a second (probably more like a tenth of a second)...

I swear, they behave exactly as if they have a ballast or electronic transformer (like a fluorescent bulb) or something that takes a few seconds to fire off initially, but responds progressively faster as it warms up during the first few minutes of operation...