do i need to replace ignition switch 240d?

I have a 1979 Mercedes Benz 240d.
I bought it in an impound auction. It had been sitting for about a year and a half. No manuals. Never had a diesel before. It started and ran at
the auction. Some vacuum problems fixed.
The apparent procedure for starting was: turn ignition key to right the glow plug light would come on allow to heat up for min or so turn ignition further to engage starter, engine would start easily. however, the glow plug light would sometimes come on and off when I was driving down the road. I could wiggle the key and it would go off.
Now, the glow plug light will not come on when the key is turned to right. if I engage the starter, it cranks and after several tries it will start.
I check the heavy wire connections between the glow plugs, and they were hot, which indicated that the glow plugs were being energizes when the starter was.
So what is the Problem?
Jerry
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check that the alternator is charging correctly: if the plug-in module on the back of the alternator has shorted out, it may be causing the symptoms you have experienced...

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Check the glow plug relay.
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Perhaps I am not making myself clear:
1.The glow plug light comes on when the starter is engaged.
2.When the wires between the glow plugs are hot, that indicates that there is current flowing.
3.In a series connection, the glow plugs must be working, or the wires would not be hot.
Therefore, the ignition switch is not energizing the glow plug unless the starter is also engaged.
4.Prior, the glow plug light would come on, and the wires would get hot when the ignition switch was in the right position, but while the starter was not engaged.
NOW, This is not the case.
I think it is the ignition switch.
The glow plug relay must be energized or 2 would not be true.
The glow plugs must be conducting current or 2 would not be true.
Am I wrong, or is there something I do not know.
ie the left turn signal operates correctly until I press the brakes then it seems to speed up and at night when i press the brakes the left turn signal indicator lights up. This is illogical to me, but might be for someone else.
I bought the MB diesel, cause I thought it would be simple. I troubleshot the vacuum system to get it to turn off. But from what I have read, the electrical system is just a complicated.
Jerry.
Say not the Struggle nought Availeth wrote:

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you might be right. check the alternator module anyway.

bad earth connection. most likely in the affected light cluster.
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Re: do i need to replace ignition switch 240d? Group: alt.auto.mercedes Date: Thu, Oct 9, 2003, 8:16am (EDT+5) From: atwifa@'fsmail'.net (atwifa) I think it is the ignition switch. you might be right. check the alternator module anyway. ie the left turn signal operates correctly until I press the brakes then it seems to speed up and at night when i press the brakes the left turn signal indicator lights up. bad earth connection. most likely in the affected light cluster.
OR the bulb twisted in backwards
case
the case, minus a few cans!
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THanks for the comments.
I will check the alternator module.
and the ground connection on the left rear lights.
btw, when my radio is on, the horn sounds through the speakers
Anyone have an ignition switch for a '79 240d?
I like the car, no acceleration, some rust, cracks on the dask, weak radio, it just feels good while it is up to speed, and the doors sound good when they shut. jerry
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I was trouble shooting, using the manual, took off the cover below the dash, found the preglow timer relay, had key on just wriggling everything, to see if anything changed, and lo, upon tapping the relay (silver box about size of pack of cigarettes) the glow plug light came, checking the interconnectors, they were hot, so current flowing, waited a minute and started it w/o any trouble.
Repeated turning on key and tapping relay, could get the light to turn on.
Looks like it might be the preglow timer relay.
New relay is about $105. Is there any cheaper out there?
OR is this a red-herring? took the dash cover off to see if ignition switch had any loose fittings. It seemed to be fine.
Jerry
Say not the Struggle nought Availeth wrote:

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