My ignition switch is malfunctioning. When I turn the key to the usual glow-plug/on setting, nothing happens--no warning lights, no movement of gauge needles, no glow plug light, no radio, no fan, nothing. Then when I turn the key to the usual start position, the warning lights come on, along with the glow plug light, radio, and fan, and the gauge needles move. However, the key stays in that position, as if it were the on position and not the start position. Key does not spring back when I let go and the starter/solenoid does not engage either.

I can put the key in the start position and start the car with the remote starter switch.

The engine shuts-off correctly, when I turn the key to off.

Does anyone know if a new key lock cylinder will fix this or is the problem deeper in the switch mechanism?

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1984 300SD 326,997 miles and counting . . . No wait, my odometer is still dead

I am just guessing here.... as usual..... LOL.... but you might want to check to see if the functions which are messing up are ' assigned ' to the lock barrel.... or the deal it attaches to behind it.... I think this is where those things would be malfunctioning.... if it will turn/lock then it is doing its job....

I had my ignition switch fail in my 85 190E and what happened was the spring load into the start mode let go and although I had all accessories functioning properly, I had no start. I rigged a momentary switch under the dash and used it to engage the starter.

So I know something inside the switch can disable contacts. Also, my current 87 300DT has a sticky switch too but works properly most of the time. I've never had ignition switch problems in any other cars I've owned over 33 years, Just MB's!

It sounds to me like the rotary switch behind the cylinder is broken. I had something real similar occur. I removed the entire locking mechanism. You won't need to take the dash off but I already had the dash apart for HVAC issues so this was easy. There are directions here:

http://skinnerbox.steaky.org/123_DISK2/program/Chassis/46-640.pdf

I took mine apart cleaned out old grease. Relubed and put back together.

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Lindsay
1985 300D Silver w/ Black Int 288,000

Its not your cylinder. Its in the mechanism itself. My wifes car had this exact problem.

Where the ignition switch connects to the ignition assembly is a keyed shaft. This shaft had destructed on my wifes car.

I've got a very detailed webpage I am working on to go through the process if removing the ignition and replacing the shaft part of the ignition assembly if you can get a cheap donor part.

Unfortunately I'm not quite ready to put it up yet.

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'84 300CD Turbo 132k (Anthracite Grey) - WVO - My daily driver - Recently named coo-coo-coupe by my daughter.
'84 300D Turbo 240k (Anthracite Grey) - Garage Queen
'83 300D Turbo 220k (Orient Red) - WVO - Wifes daily driver

I'm not a certified mechanic, but I did stay at a HolidayInn Express last night.