I recently bought a 1984 300D. I have noticed I can move the gear
shift (US auto) up and down without the car started. I believe you
shouldn't be able to do this. Also where reverse is located the
shifter is between Park and Reverse. Anyway I think this causes the
car not to start. I can get it started no problem, run an errand, and
when I hop back in it won't start. I can try to start it 5 or 6 times
and it won't crank (normal glow light and buzzer). So I did an
experiment and put it into N and it started right up. I did this a
couple of times. Is there a gearshift switch and if so is there an
adjustment to fix this problem? Thanks
Yes, there is a starter safety switch... on driver side of tranny and black
thing by the privot. Sometime, your bushings on these linkages are shot or
gone so the alignment is off... get these bushings from dealer...cheap
enough and pop them in with help of plier.
Safety switch is easy enough to change.
No, they are two separate things... you see, the bushings keeps it align so
when they fall out or deteriorated, the neutrals safety switch sometime
think it is still engaged in gear... so you can't start.
There was no gear shift interlocking back in the 80s. For many modern
cars, the gear cannot go out of Park without stepping on brake and key
in run position. That was not the case 20+ years ago.
This statement is only partially true. I have an 84 300D that will
only start in neutral or park. I know this because when I bought it I
hadn't owned an automatic in over ten years, and the second time I
tried to start it, it wouldn't start. This was because the first time
I had left it in drive and used the parking brake. Oops. If you have
an 80s car that doesn't have this feature, it is broken. I have also
owned cars from 70, 71, and 78 that all had neutral safety switches on
automatic transmissions. They weren't Mercedes, but that switch is not
You are right about the interlock that you mention concerning the
brake and shifting out of park. This is a relative newcomer, but the
shift linkage tied to the starter circuit is old.
I was only mentioning about the interlocking, which came out in late 80s
after many incidents of sudden-moving-forward (the most famous is
probably Audi 5000).
The neutral safety switch on automatic transmission is old, probably
older than me :-)
if you have to replace the neutral safety switch to not purchase a
rebuilt one battery manufactured in China and do not work. I spent a
day trying to get one of these rebuilt ones to work. Replace it with
OEM only. An original equipment manufacturer
So I went looking under the drivers side and found the linkage (I
think). However I don't have ramps to jack the car up. I think I
could live with it for the time being. Sounds like they must be
rubber or something like that. I mean the linkage is off so the
gearshift is off to the corresponding P,R,N, etc. The safety switch
works. It's too bad the tranny manual is not included with the regular
service manual. :-(
Thanks for all the advice.
If the linkage is really loose as it plops in the hole, there is that
bushing that is missing or loose. Old one is like silicone... new one is
more rigid plastic that flex only enough for you to slip it in with pliers.
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