automatic headlight switch - PeachParts Mercedes-Benz Forum

John Schroader · #1 10-28-2011, 10:19 AM

As a safety precaution, I often drive in daylight hours with my headlights on (my car is a non-descript gray). Maybe the years are cathching up with me, but I sometimes leave them on after I exit the car. I'm sure there are retro kits that I could purchase to automatically turn off the lights (off delay timer) when I kill the ignition. The advice I am seeking is this ---- given the vacuum shutoff system on my '83, is a typical off the shelf kit applicable? I would assume that most gas cars shut down with the removal of voltage to the ignition. Any advice?

psaboic · #2 10-28-2011, 11:30 AM

Let me know if you find out anything.....I've left mine on a lot over the years too, and those off the shelf buzzers you can buy at your local auto parts store never seem to work right!

vstech · #3 10-28-2011, 12:15 PM

there are plenty of acc key powered items in the car, so if you find an autoshutoff switch, just connect it to sense power on the cigar lighter circuit or similar key on only paths...

John Schroader · #4 10-28-2011, 12:26 PM

Quote:

Originally Posted by vstech

there are plenty of acc key powered items in the car, so if you find an autoshutoff switch, just connect it to sense power on the cigar lighter circuit or similar key on only paths...

That surely makes sense. Thanks for opening my eyes.

LandYaghtLover · #5 10-28-2011, 12:30 PM

I am not sure of the wring on these cars, but on some other cars I have seen people move the headlight power to the accessory side. But this is done when its know the accessory wiring can handle the load. Its the quickest and least intrusive way since it just requires, usually, moving a wire behind the fuse panel back. No need for adding a relay and more wire.

John Schroader · #6 10-28-2011, 12:45 PM

Quote:

Originally Posted by LandYaghtLover

I am not sure of the wring on these cars, but on some other cars I have seen people move the headlight power to the accessory side. But this is done when its know the accessory wiring can handle the load. Its the quickest and least intrusive way since it just requires, usually, moving a wire behind the fuse panel back. No need for adding a relay and more wire.

I'll look into this also. Many thanks. This forum is tops.

Jeremy5848 · #7 10-28-2011, 01:13 PM

The '83 300SD should have a built-in buzzer to alert you if you leave your headlights on after you shut off the engine and open the door. Maybe yours is simply inoperative?

sixto · #8 10-28-2011, 01:15 PM

How about a headlight reminder chime like in the W124 using the 87a pin of the common Bosch relay? That way you can have the headlights on with the engine off if that need should arise.

Sixto
87 300D

Zulfiqar · #9 10-28-2011, 03:04 PM

routing through the ACC key position should be good, better through ON position, use a relay to keep the switch contacts free of any extra load, A great way would be to intercept the main current line at the headlamp switch and route it through relay contacts 30 and 87, the key can provide positive to contact 86 and contact 85 goes to ground.

voila - great circuit to cut off the headlamps when you key off the engine.

I loved my VW Golf for this, the key on position also carried positive supply to the headlamp switch. It also had a load reduction relay that cut off power to nearly all items on the car, headlamps, A/C blower, rad fan and stereo for full juice supply to the starter.

compu_85 · #10 10-28-2011, 03:07 PM

Do the standing lamps and parking lamps get their power from the same source?

-J

Orv · #11 10-28-2011, 04:10 PM

Quote:

Originally Posted by Zulfiqar

I loved my VW Golf for this, the key on position also carried positive supply to the headlamp switch. It also had a load reduction relay that cut off power to nearly all items on the car, headlamps, A/C blower, rad fan and stereo for full juice supply to the starter.

My VW had the headlights on that circuit but not the parking lights, so I still managed to run the battery down a few times.

I think the cleverest design was a Saab 95 I owned. It had a little bit of relay logic in the circuit; if you turned on the lights while the car was running, they would turn off automatically when you turned off the key; but if you switched them on with the car stopped, they would come on and stay on. So you could still have the parking lights on if you needed them, but you couldn't leave them on by mistake.

LandYaghtLover · #12 10-28-2011, 04:18 PM

That Saab thing is cool. I just miss having a "power sentry". My Mark VIII had it. If the draw was too much on any system in the car, it would kill power until the brakes were pushed or keypad entry was used.

Jeremy5848 · #13 10-28-2011, 08:29 PM

I also drive with my headlights on in the daytime. My 124 buzzes at me if I leave the lights on so that's not a problem but what I'd like to have is headlights only for daytime, that is, no taillights or instrument lights. With the 124's lamp failure module, I suspect it would take some special switches and/or relays to turn on just the headlights.

Jeremy

sixto · #14 10-28-2011, 10:01 PM

In our '97 Suburban the DRLs come on with the engine running and the park brake disengaged.

Jeremy, this is off topic but you can check how Canadian 124s manage DRLs. It might simply be a relay in an existing socket or a market specific illumination relay.

Sixto
87 300D

MBeige · #15 10-29-2011, 03:02 AM

Quote:

Originally Posted by Jeremy5848

The '83 300SD should have a built-in buzzer to alert you if you leave your headlights on after you shut off the engine and open the door. Maybe yours is simply inoperative?

Can't remember how many times the buzzer has caught me leaving the lights on when driving during the day, after I've just parked the car and was about to get up from the driver seat. I must be getting old too

I use the lights even during day time, and especially when driving into or from the sun.