Jumped in my 85 300D and turned the key.
Position 1 - Nothing.
Position 2 - Glow Plug buzz as normal for Position 1
There now is no Position 3. Key advances no further. No way to start it up.

Bad lock cylinder or.......?

Thanks!

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85 300D

If it is like my SD, there is a plastic terminal box on the right fenderwell under the hood. You can set the car to glow the plugs and start it with two screwdrivers touching two of the bolts in the terminal box. It should make the starter jump. Touch the screwdrivers together.

That's how I got him home!

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85 300D

This happened on my '85 300D a few years ago. The culprit was the connection between the ignition/steering lock unit and the switch behind it. I would have to dig out a PnP spare to refresh my memory of exactly what it looked like. But I remember a small square on one part fit into a small square on the other. Over decades it rounded off so that the key would not turn the switch quite as far as it needs. I think the worn part was the ignition steering lock not the electrical switch. Pull it apart and it will be obvious.

If you're willing, remove the dashboard lower panel and look up at the back of the key switch .

You should see a white / yellowed plastic thing with many wires coming out of it .

Two screws will allow it to be disconnected BUT BEWARE ! the wires have a bad habit of all coming loose so take a good well lit picture of it *before* you undo it to check the worn parts .

If, once you have the plastic switch part hanging down, you see a crack in the side of it , STOP and go buy a new one, make a map of what color wires goes into that numbered hole, there's lot of tiny little molded in numbers that explain what color wire goes where .

If you're annoyed at reading that last part, imagine how upset you're going to get if/when it all falls apart in your hand .

The GOOD news is : the part isn't expensive and the job isn't difficult,it just takes time and patience .

Many here have dome this and posted diagrams, sketches and links to picures of how it all goes back together .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

Thanks! Do you just happen to know what that part is called?

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85 300D

There is a buzzer for the seat belts not the glow plugs.
In position 1 your warning lights will come on.

There is the key, the lock tumbler, the steering column lock and the Ignition switch.

I had the innards of my steering column lock break in 2 places. I thought it was a key and tumbler issue. I also found that there was a contact burned away on the ignition switch.

A new steering column came with a new ignition switch and a new vacuum switch on it. (The supply of steering column locks had previously dried up and I don't know if they ever returned.)

I installed a new steering column lock, and everything was fine for about 1.5 years when my tumbler fell apart.

If it was me, I would get the steering column lock off and apart to see what is going on and you can take a look at the ignition switch and the tumbler.

http://www.peachparts.com/shopforum/diesel-discussion/333785-steering-colum-lock-ignition-lock-housing-causes-ignition-switch-failure.html

http://www.peachparts.com/shopforum/diesel-discussion/334172-ignition%5Ctumbler-issue-2.html

http://www.peachparts.com/shopforum/diesel-discussion/387730-another-type-ignition-lock-tumbler-issue-w123-pictures.html

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84 300D, 82 Volvo 244Gl Diesel

202-545-01-04
Ignition Switch 202-545-01-04
https://cdn2.pelicanparts.com/catalog/images/SuperStock-Priority/202-545-01-04-MBZ.jpg

I can't seem to copy the image, this is a link to it .

123-462-04-79
Ignition Lock Cylinder with Key

Part #: 123-462-04-79-M36 LINK TO IMAGE : https://cdn3.pelicanparts.com/catalog/images/SuperStock/123-462-04-79-M36.jpg

I don't see the steering column lock, the catalog has been recently revamped, I'm sure if you look at the other thread links provided you'll find the part number and can find it elsewhere on the web *if* you need it .

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-Nate
1982 240D 408,XXX miles
Ignorance is the mother of suspicion and fear is the father

I did then what I knew how to do ~ now that I know better I do better

The supply of steering column locks was drying up several years ago.

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84 300D, 82 Volvo 244Gl Diesel

Official Mercedes classic car parts site?

https://classicparts.mbusa.com/

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84 300D, 82 Volvo 244Gl Diesel

Hope yours isn't like the issue in my 1984 300D. It felt like the tumbler was jamming, but when removed, it turned fine. At least you can get your key to the "can unscrew front nut" position where you can push in a thin screwdriver to push down the security tab. In mine, the culprit was a broken detent spring mount down deep in the cylinder stalk. I had to pry off the steel cover to find it. The spring mount is thin die-cast aluminum so easy to break over time. I just removed that spring, so I don't get as solid clicks, but the key has never rotated on its own while driving. Wish I had removed the steering lock rod while in-there, since not much theft prevention and only causes problems.

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1984 & 1985 CA 300D's
1964 & 65 Mopar's - Valiant, Dart, Newport
1996 & 2002 Chrysler minivans

When I got my new Steering Column Lock, I shoved the plunger/rod up inside and depressed the pin on the side, so it held the plunger/rod inside and epoxied over the pin. See attached picture.
When that is done Tumbler is not turning against the plunger/rod spring tension.

If for some reason you cannot access the attachment the same picture is on post #7 of this thread. http://www.peachparts.com/shopforum/diesel-discussion/407345-if-new-1980s-300d-steering-colum-locks-gone-what-do.html

Attached Thumbnails

 

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84 300D, 82 Volvo 244Gl Diesel

Replaced electronic ignition switch… nada. Gave up and ordered a whole new assembly with tumbler. Thanks, all!

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85 300D