Just bought my first diesel truck. 97 12v Cummins. First off the tach and Speedo don't work.replaced the 120amp alternator and belt, and two red to optima batteries, I can go a full day driving just fine next day halfway through the batteries are dead. Won't die while running just when you shut it off it won't start again. Charge em up their fine. Did a power check on the batteries while running batteries aren't getting a charge from alternator. I tried the ford voltage regulator to truck the alternator into charging, didn't work still slowly drains. Does anyone know what in the world is going on. This is my daily driver and need it reliable asap!

 

Have you thought of getting the new alternator checked? New does not mean perfect.

 

Your crank position sensor is bad thats also why your tach and speedo are not working.

 

I second crank position sensor

 

I replaced the crank position sensor. Want able to use & feeler Gauge used & piece of card board close to .050 I guess I'll just have to get a feeler Gauge should it be snug tight lose?

 

could also be PCM fuse...

 

where's that located?

 

Check the alternator fuse located in the fuse box under the hood in front of driver, it is held down by two small bolts

 

Is that the yellow accessories one?

 

The alternator fuse is the 120 amp fuse. It is the one closet to the engine and is held down by two small bolts. You can find it by tracing the 8 gauge wire from the positive battery post to the fuse. Mine is white not yellow but I has also been replaced.