won't crank when cold
 

my 85 300cd starter won't crank if temp gets 25F or less.I can however cross the wires at the fender and it will go so I don't think its the starter or solenoid.my thinking is that it may be in the ignition switch.has anyone had a similar problem ? ed

Could be an ignition switch, trans selector switch, or starter.

I would try holding it in the start position and rock the selector from Park to Neutral.

What happens on Starter Lock-out switch [ N safety] is they get water in them BC of their location down on the side of tranny.... so, when temp drops below freezing , the points do not make contact..
If that is the case , best to replace the sw...

thanx for the replies.I' like to look at that nuetral safety switch at trans and I'm wondering if there is a way to jump or bypass it to positively identify the malfunctioning component before I start replacing things. ed

The N sw. is 4 prong. Pins 3/4 should be for Engine starter
circuit. 1/2 are back up lamps.
The plug has a plastic saftey lock ring that has to be turned in order to unplug the harness at the sw.
On some models there is also a plug above the gas pedal in the cabin that you can get to. [ same harness coming from the tranny, through the floor]
If the car won't turn over in the cold [ like today !!! ] , hit the sw with a hair dryer and see if that melts the suspected ice formation.... if it does , just replace the sw......

I like the hairdryer idea but its just too darn cold to mess with it today.one thing i forgot to mention in my original post is that plugging it in overnight solves the problem which sort of points to another area as the block heat could never get to trans.I guess I could try heating the trans sw one day and then the starter solenoid another and see if it has any effect .again thanx for the help ed

<< the block heat could never get to trans.>>

Think I will differ on you with that.
An aluminum tranny case directly bolted to an engine block is certainly going to absorb/transfer engine coolant temps..
Plus the trans fluid cooling lines go to the radiator where they will pick up heat

Let us know when you find the culprit...

Arthur is offering some good advice. The block heater will do more than you think. You don't have to heat up the transmission enough to fry eggs, you only need to get it above 32 degrees F.

Please don't jump the neutral safety switch. You are setting up potentially very dangerous situation. The neutral safety switch is inexpensive and not a big deal to replace. The name of this device does not include the word "safety" for nothing.

Good luck,