Electrical connector at rear of ignition electrical switch w123
 

I have the entire ignition lock assembly dangling out under the dash of an '84 300td parts car. I need to swap over the lock to my '85 300d and install at the same time a new electrical switch and tumbler. (I removed what I thought was a sticking tumbler to find that the problem is with the lock mechanism.)

Here is the issue: I cannot get the plug out from the back of the electrical switch. I have tried prying it, and pulling/jiggling/twisting it by hand and with a set of slip-jaw pliers. It does not want to come out.

It isn't my parts car, so I don't want to cut the harness.

Anything I am missing on this? I have my new electrical switch in hand and I don't see anything that would be holding the plug in there, except age(?).

There is a procedure for doing it with the key.

The electrical connector simply pulls out. Try spraying silicone lube in there as you wiggle it. For sure, put the new switch on the stem before putting the stem on the column. Otherwise, it is a bear getting at those 3 screws.

Sounds like your problem was identical to mine in my 1984 300D. There is a spring detent inside the "stem". It broke off and would jam the rotation. I had to pry the steel plate off the back to get at it. The spring is in weak pot metal, so I expect most will eventually break. I only wish I had left out the steering lock when I did this job. The typical answer is "bad tumblers" and the Car Talk guys even said that when question came up a few years ago. Mine still jammed with the key tumbler out. You might be the first to believe me.

I suggest a forensic tear-down of your old one, and fix it to be ready when your replacement also fails. I secured the steel plate by swaging over the aluminum (as factory did), plus epoxy.

Not the first, a couple of other folks have posted in other threads about it.

I suspect it's one of those things that will become more prevalent as the cars get to the age they are now.

On the older Models the Electrical Connector that plugs into the Ignition Switch can be removed no matter what position the Key is in but not so on the late W123s.

In the picture the old Steering wheel Lock has a Plastic T piece that has to be rotated by the Key and Lock Tumbler so it indexes and the Ignition Switch Electrical Connector can be removed.
Also you notice that the later model Switches are surrounded by Aluminum.
The much older ones don't have that deep Aluminum Socket.

For some reason the replacement Steering Colum Lock does not have the Plastic T. Also the Replacement Steering Colum Lock from the Dealer is not made by the same company as the original was.

Ask Hunter how to deal with it. Since you are going to repalce the Steering Colum Lock Assembly I remember Hunter saying to cut the 3 Ears on the Main Body of the Steering Colum Lock that the Screws that hold the Actual Ignition Switch into the Housing.

Once that end of the Housing is of you will be able to get behind and roate the Ignition Switch till that T Piece is properly indexed and you can pull off the Electrical Connector.

Only 2 Ears show up in the Pic.

Okay but the one I am trying to remove is the one I need to pull off the parts car to install onto my car. So grinding off the ears doesn't get me anywhere.

On my 1980 300D the plug into the switch will come apart. There are some ears on the plug cover that release it. The wires then all come loose and you should be able to remove the lock assembly with the other half of the plug still attached.

I secured the locking pin that goes into the steering wheel shaft to prevent its turning with JB Weld epoxy so that it will not engage with the steering. That way I did not have to find a new lock assembly which are no longer manufactured for the early 123's.

Richard

Then you need to rotate the Steering Colum Lock innards till the locking T indexes with the slot in the Electrical Connector so it can be pulled out.
That Sweet Spot is the same Key Position as is used when you remove the Lock Tumbler

An old post but this is the answer.

On some (later model W123's), the only way to remove the electrical connector from the ignition electrical switch is with the ignition key to turn the tumbler to the same position to remove the tumbler (I think it's position 2). Without the key, it is not possible without breaking something IMO.

On 1982-85 123 models, the key needs to be turned to the number one position in order for the electrical plug to be removed. As stated before, the plug is internally locked into position at any other position.

Bingo...this is the correct info.

Must be in position one to remove the Ignition Switch.

Must be in position one to remove the little black switch for the buzzer.

Must be in position one to be able to push in the locking pin.

Vehicles manufactured from middle of 1980 the plug connector can be
pulled off only in position "1", since it is locked in all other ignition
key positions. 46-640

NO cutting off of any little ears.


Charlie

Someone would have to read Hunter's thread on cutting off the Ears to understand it. You only do that when the Steering Colum Lock itself cannot be rotated.

On my Steering Colum Lock the shaft inside of it that turns/rotates the Ignition Switch broke and would not rotate the Ignition Switch. Others have had other Parts inside of the Steering Colum lock break so you could not rotate the Ignition Switch.

Those are the cases when cutting the ears off of the Steering Colum Lock would allow you to get behind the Ignition Switch and rotate it so you can disconnect it from the Connector.

Note that since the Steering Colum Lock is damaged to begin with and is going to be replaced it does not matter if you cut the ears off of it.

Also note if you buy a new Steering Colum Lock you get that, a new Vacuum Switch and a new Ignition Switch for much less then if you purchased them separate.
That turned out to be important to me because on my old ignition switch I found that one of the little contact point discs was burned entirely off of the contact arm. So besides the Steering Colum Lock itself I needed a new Ignition switch. So it made sense to replace the whole assembly.

I would also like to say that when my Key would not rotate I assumed that it was the Lock Tumbler from the symptoms. However, I recommend that someone looks further in to it and actually take apart the Steering Colum Lock to inspect the innards.
Also that was several years ago and I have had no issues with the Lock Tumbler or the Steering Colum Lock.

There should be pics in this thread:
http://www.peachparts.com/shopforum/diesel-discussion/333785-steering-colum-lock-ignition-lock-housing-causes-ignition-switch-failure.html

I'm having trouble finding this thread. Can someone help me? I think I need it after spending way too many hours trying to get the wiring off of the back on the lock unit. Time to start cutting. TIA!

With the tumbler removed, use a medium size flat blade screw driver inserted into the slot where the back of the tumbler engaged the ignition switch housing. Using the screwdriver turn the switch to the number one position (turning right) and pull the electrical plug off. No cutting is necessary.