1998 3500 4x4 auto 24v wont turn over, no sound at all when key is turned. No power to exciter wire on starter. I can jumper to exciter wire and it does turn over.
Whats the common issue?

 

Failed starter relay in the PDC? Bad neutral safety switch?

 

Swapped the relay and no change.
I like that thought, where is it?

 

Try starting it in neutral if it does start it's the switch. It's located in the tranny drivers side right above the pan, should have a 3 pin connector

 

Will do.
With 3 wires any clue how to bypass it?

 

Like I said I think 3 wires some things changed in those years. Not to my knowledge is there a way to bypass it, but even if there was I wouldn't recommend it. It's there for safety (do you don't try to start it in D). All they do is complete a ground circuit if I'm not mistakin so you could theoretically ground it and it should work. But don't hold me to that was never really interested in how they work lol

 

So the plot thickens.
Pulled neutral safety switch and checked connection and looked good. Grounded the brown wire (hear that disables the switch) no change, still nothing.

Than tried starting it in neutral and it turned right over. Well **** me why did I not try that before. So unplugged jumper on brown wire and plugged it back in to trans and still wont turn over in Park but does in Neutral.

What ever I can start it there. Now next issue, it does not start. I'm no diesel mechanic......where do I start to look for start issue?

Gas motor I'd be checking for Fuel, Spark and doing compression check. This beast I have no idea.
Thanks again

 

May wanna post the no-start problem in the diesel section....... I don't have a clue when it comes to the oil burners.