1979 300D ignition problem?
 

I can jump the car at the starter but get nothing from the ignition. The dash lights come on but the switch does not engage the starter.

Can anyone help?

Do a search... there are some great threads on this... step by step in a logical fashion....
I assume you have checked your battery ?
The connections to your battery and to the engine and from the engine to the body are all clean and tight ?
You have checked your fuses ?

What terminal are you jumping to? There are three terminals. Two large and one small. If you are jumping to the smallest and the starter works then it is in key circuit or small wiring or even transmission starter lockout switch. Are you jumping from the battery with something like a booster cable or just jumping from one large terminal on starter solenoid to another terminal on the starter solenoid? :)

It started once in neutral after I shut it down it would not start again. I think it's the neutral safty switch.

Easy enough to verify if it's the switch or not. Think there are four wires on it . Two are for the back up lights and two for the lockout switch for the starter. Colour code of wires posted in archives or service information. Shorting the two for the swith together with a friend turning the key in ignition to start will clear or condem it fast. Another simpler approach is to perhaps leave transmission in neutral and see if switch has continuity with a meter or test light with a battery. :)

thanks will try

wedge1,

Diesels don't have an "ignition".

Correct terminology will get you a correct solution.

P E H