I bought a 1983 300d. The headlights and front turn signals dont work. Car starts and runs fine with a good battery. I put all new fuses in and cleaned the holders. The ground wires behind the passenger headlight are in good condition with no corrosion.
I'm thinking the switches are bad. I believe the combination switch controls the turn signals and the headlight switch just does the headlights correct? What r the chances of them both being bad at the same time? Also, will those switches from a 1981 240d fit in my 300d? Thanks, Jeff

IIRC the headlights are wired through the combination switch which handles low beam and high beam (and wipers). The combination switch from an ‘81 240D should work in an ‘83 300D.

Sixto
98 E320s sedan and wagon
02 C320 wagon

High low beam switch in the stalk is possibly open. If the directional signals where absent from both ends of the car. The multi function switches in there would probably be it. Instead you have rear signals so it is not a slam dunk.

Easiest way is probably to follow the voltage with a test light or meter until you find where it is no longer present. Where it should be for the headlights. Just to save possible pain make certain you do not just have a batch of burnt out bulbs.

When you turn on the headlight switch if the rear light bulbs light. The headlight switch is probably okay.

Dealing with electrical issues varies a lot with knowledge and experience levels. What is hard for me may be easy for you and vice versa. The only thing I think is probably common to the headlights and the front signal circuits. Is they may share common grounds.

I recently repaired my combo switch in my got a 1985 300d thread. The plastic plunger for high low beams had worn out in mine. I guess the PO liked high beaming people.

Easiest is to buy a cheap uro combo switch and replace it. Or, pull from the junkyard. Your 240d unit sounds like just the ticket here. Swap and be done with it.

I had some time to waste so I tore mine apart and found the culprit inside the switch. I had to drill out the brass rivets and replace them with 2-56 or 1-72 (cannot recall) screws. It was fun to see how that thing ticked inside. Almost like clockworks.

Edit - the teardown

http://www.peachparts.com/shopforum/diesel-discussion/394730-got-1985-300d-turbo-5.html

Post #72

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79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

Thanks all, to clarify the issue some. Headlights do not work, hi beams will work only if I pull back hard on the stick. Foglights do not work. No other outside lights front or back work. I will replace the combination switch first and see what that cures. If needed I will then replace the headlight switch.

Yes the combo switch in the stock is shot from your description. Usually it will be only one item is the issue. Whatever fails that involves the headlights is usually addressed too fast to expect additional failures to exist. It appears the fog lights will not work with your issue present either. As one poster pointed out. They only work in the low beam setting of the stalk.


Basically the issue is not usually deffered as an option to have the car usable. For example if even one headlight bulb burns out. I replace it as soon as possible. Otherwise a ticket and limited night visability would ensue. Both headlights out I am going nowhere after dusk.

All lights out might be someone did something before you got the car. I would start by changing that combo switch as it is bad from your description and see what I had. That you can activate the high beams only by applying steady backward pressure.

The only exception to this is if your vehicle has the built in provision or feature to flash headlights at other drivers. By doing this. I never noticed it on my old Mercedes but it might exist. Other members will know. Just keep an eye out for work others may have attempted on the lighting circuit to get it working again as you go along. It is almost always better to not follow some ones previous attempt at a repair. That failed.

I got both combo switches pulled today before I had to go to work. The combo switches Ch from the 300d has the cruise control stick where the 240d does not. I'm a little confused, do I replace the entire assembly or just certain parts of it? Will I be able to wire the cruise stick into the 240d combo switches?

I got both combo switches pulled today before I had to go to work. The combo switch from the 300d has the cruise control stick where the 240d does not. I'm a little confused, do I replace the entire assembly or just certain parts of it? Will I be able to wire the cruise stick into the 240d combo switch?

Ok...my memory isn’t that good. I thought my 240d had a cruise lever at the same place as my 300d. Perhaps I got it wrong. No, pelican says both use

pn=005-545-41-24-MBZ

Maybe you combine the two parts? Good luck.

Edit - oops, looks like the above part doesn’t include the cruise lever. I just pulled mine apart a month ago...shame I cannot recall the relationship between the two levers. My gut is that the cruise just separated off. There are two plugs and now that I think about it the wiring was a little intertwined. I think you’ll have to do some mix and matching with your parts.

__________________
79 300TD “Old Smokey” AKA “The Mistake” (SOLD)
82 240D stick shift 335k miles (SOLD)
82 300SD 300k miles
85 300D Turbodiesel 170k miles

First, thanks for all the replies. Problem is partially solved.
1) I took the headlight switch from the 240d donor and put it in my 300d. The parking lights worked and the warning buzzer would now work but still no headlights.
2) Next I put the donor combination switch in. Still had hi beams. Strangely the turn signals worked for about 3 mins then stopped. The passenger side rear bulb was flashing very fast.
3) After fiddle farting around some I tried the headlights again and they worked! Had low and high beams and the fog lights even worked now. The donor car sat for about 4 yrs and I'm thinking maybe the switch had some corrosion inside and after working the switch back and forth enough times it started working. The headlights would not work with the old combo switch reinstalled though. I was just curious if they would.
4) Still don't have turn signals and the emergency flashes don't work so I ordered the relay and hopefully that will take care of that issue.
All in all I'm happy. New combo switch doesn't have a cruise stick but I can live with that for now. Just waiting on the flasher relay now.

Also, I forgot to add that the old headlight switch literally came out in pieces when I removed it. Lol