This problem arose just last week as I have never had a starting problem on this car in 3 years of owning it. It seems that when the key is put into the start (crank) position nothing at all happens (all lights come on as normal). Voltage readings on the battery (2 years old) during "cranking" is right around 12.7 vdc, so I am ruling out a battery prob. The "key" to this problem lies in the outside temperature (maybe, along with something else) as it never occurs when the ambient temp. is 60 degrees F or above. But, I am thinking it might also have something to do with the transmission interlock, as shifting it from P to the drive settings and back to P got it to start. So....is there something about that transmission interlock that can be temperature affected??? I surely don't want to go thru this all winter long...help, please.

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1996 SL320 97K miles
1996 C220 130k miles
1992 500SEL 170k miles <---sold
1986 300E 216k miles <---sold

Probably the neutral switch.
Next time it doesn't start in P, move to N and try to start there. If it does, it is probably the neutral switch.

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1999 Porsche 996 Carrera Convertible
1994 420E - SOLD
1986 300E - SOLD, what a car
609 Certified

Check the bushings at each end of the linkage rod. They may be worn or missing entirely (like mine were!), which will cause the problem described.