On my 96 B2500 Ram Van is the oil pressure light going on and the pressure drops.
Some times the light ist just blinking when i accelerate without dropping down the pressure.

Any suggestion?

 

Check the oil level.

 

checked and changed oil, oilfilter and airfilter, problem persist.

 

Could it be the oil sending unit switch?

If yes, where is it located?

 

That sender switch should be located passenger side, next to the distributor. I haven't experienced one fail or failing but if yours is it's easy to replace and low cost.
You might check the wiring and connector and clean them up if needed first.

 

It's the oil sender, muck in the pan clogging the pick-up tube, or a spun rear main bearing.

 

i have been having a similar issue. after driving for a few hours,
i stopped and noticed my oil light turned on and the needle just dropped. started up the van after a few minuets and everything was fine. drove a few more hours and it happened again.

i just put some oil in and it is still doing it, more frequently now. like everytime i go to stop, even at stop signs/lights.

i recently repalced the air filter and thermostat. maybe i should get another oil change? i am due for an oil change in a few hundred miles.

 

How is the oil level?

 

saturday it was low so i added 5qt and it was fine.

 

Low?? If you had to add 5 quarts, it was not low, it was empty. No wonder the oil pressure was reading low....