Headlight delay when I turn them on W123
 

When I turn the Headlights on in the 1981 240D it takes about a second or two before the headlights go on.

Did I just not notice this or is something failing? I don't want to sit back and wait for them not to work when my Teenager is trying to drive home at night.

Thanks

Are they plain, old school lights? If so they should come on instantly so I would investigate. The newer style takes a moment to charge or whatever it is they do.

-Rog

My 1982 300TD does the same thing. A 2 -4 second delay before the headlights come on. I have had this situation for about 2 years. The lights have never failed to come on.

They are old school, original lights.

Just regular old U.S. Spec headlights.

My 1979 300D did the same thing, and then began getting progressively longer and longer. It was caused by a bad headlight switch.

The contacts inside get oxidized over time and when turned on the resistance caused by it is very high until it burns through and makes a good connection. At least that's how it was explained to me.

I replaced the switch with one from the wreckers and never had the issue again.

Sounds logical.

It was the switch, fresh switch installed for 100 bucks.

It took 2 1/2 minutes for the headlights to come on the other day, I had to fix it.

I knew that didn't sound right. Thanks for posting the fix, I'll add that to my bag of knowledge.

-Rog

its the grease in them thats old and sticky... I just live with it I noticed it is worse when cold. If there was a way to squirt some WD40 in there it might be effective

With headlights, you want something that you know will always work. Mine got to the point where it's was like 5 minutes before they would come on.....

A few seconds is one thing, but 2 1/2 minutes? My 16-year-old daughter drives this car, it needs to work. Myself, I would have lived with it.

I'm sure I could have fixed it myself, but I just don't have time.

That is something you don't want to mess around with. High current dc plus high resistance = fire. Especially in a 123/124/126 where the feed is straight from the battery with no fuse. It's not like your house lights fed from 120 V ac that hums and has enough voltage to make serious arcing noise. DC does not hum on overcurrent, it just gets hot silently, and 12 V dc not high enough voltage to make arc sounds loud enough to hear over road noises.

If I turned my light switch and I did not get instant light I would be all over that in a hot New York minute.

A fuse won't protect against a hot connection. Because the connection is poor, the impedance in the circuit is LOWER than it would be with a good connection, therefore the current draw is also LOWER than normal. The heat comes from the resistance of the connection itself. Once it gets hot enough, it "burns through". Do that enough times and it just burns.

If I had a delay in my headlight switch, that switch would be popped out for inspection the second I got home...