The tach quits working also windows, the voltage drops. this comes and goes.If you shut off engine when the tachs not working and voltage is down it won't start only with a jump,95 diesel

 

Sounds like a bad connection on your batts or main feed from your left batt.Clean your cables and grounds and the main feed wire to the fuse box on the fender.

 

Tach drops to zero and voltage goes down. Sounds to me like your Crankshaft Position Sensor (CPS) is dying or has a loose connection.

Heres how it works. The tach gets its feed directy from the CPS. CPS dies and your tach will drop to zero.

The computer controls alternator output. The computer uses the CPS to know if it is running or not. If the computer gets no reading from the CPS it will think the engine is turned off and kill the alternator output.

It also affects the A/C compressor. The computer won't engage the compressor unless it thinks the engine is running.


Look on the front of your engine your will see the CPS on the upper side of the harmonic balancer I would check the wiring as that is somewhat more common than the sensor going bad.

 

time to clean ur battery terminals and all the use some sanding paper to clean up all the wire connectors...tighten the stuff really well and you'll be fine to go...the cummins takes alot to start ..if ur connections and batteries arent in top shape there's no chance you'll start

 

I agree with the terminals on this one. If you cant start it then there is either no juice in the batterys or the terminals are not making a good connection.

Jason