Well if the title doesnt say it all. This happend the other day. I just got in the truck and boom: A/C was hot the wait to start light stayed on and it wont go into overdrive. I put a meter on it and its giveing about 11.5 volts out and hanging on start up. I am thiking new alternator for that as the one on it looks OEM no biggie. But would that make everything else go out?? Any thoughts are welcome. Thanx

 

I think "wannadiesel" answered your question in the thread listed below.

Good luck

https://www.dieseltruckresource.com/...d.php?t=214322

 

Check the spedometer speed sensor, loeft side of transmission, one big nut holds it in place. If it gets loose it wears the square drive pin round.
I went thru 2 under warrenty and then had to buy my own. The bastards at Dodge never tightened them enough. When I had topay for it (13 years ago, I tightened it a little better than they had and no trouble ever since.
Bob 92, auto.

 

From all your symptoms, I would take a close look at the crankshaft position sensor and the wires that go to it. Take a good look at the plug that is in front of the #1 valve cover and the wiring going down the front of the timing case to the sensor.