Okay, so let's keep this simple. The tachometer fluctuates, the CEL comes on and goes off erratically, but the engine stays running. I did a keyon check, and it says no codes, bad battery connection. Never mind the lights sometimes die, and never mind the engine died a few times. Ideas?

 

Tach fluttering is typically either a chaffed signal wire, oil in the connector of the ESS, or loss of voltage to run the ESS.

I have never personally had a CEL come on when I had a problem with the tach.

Do you have a factory service manual?

 

Clean and check the ground at G119 and see if that helps. Ground 119 corries the load for much of the thinks you describe.

 

I don't have a factory service manual, but I do have a Chilton's and a Haynes repair manual, of the common type available at Napa and so forth. I don't know where G119 is, but I can probably find it in the Haynes book. I'm going to clean the battery terminals and see if that helps, too. But I have been working 7 days a week for two months, and no end in sight! Need to find some time to work on the pickup.

 

Look at the picture i put up, G119 is on the engine, just in front of the grid heaters.

Looking through the FSM, that ground connects to several of your issues, and I really can't find a common voltage supply point, so I hope it is a ground issue.

Don't waste your time with Chilton or Haynes, they are WAY too generic and skimpy to be useful past the very basics.

You can get a real FSM on CD for 35 bucks, I just print out the page I am looking at and can take it right to the truck without worrying about ruining my printed FSM.

http://www.genosgarage.com/1997-DODG.../#.VFBC9Wer-rg

If you intend to keep the truck, it is a lifesaver......

 

Awesome buddy, thank you.

 

Turns out it was the engine speed sensor (crankshaft position sensor.)