2001 tachometer issue

I have a 2001 ram 2500 24 valve

with tachometer issue ,it dies after 3 to 4 seconds engine still runing check engine light is on , I have replaced the cam sensor ran for 20 to 30 sec then it died again engine still runing ,replaced the ecm with another oane same problem did any oane have this issue,I am a little confused at this point as the wires that plug into the sensor check out good any help is appreciated thanks

Does it have a crank sensor as well? I forgot what years but some only have 1 not both. If it has both it can calculate values from either sensor to get TDC.

If I remember correctly the rpm is picked up by the eye inside the VP44 injection pump.

01/02 trucks read off the back of the cam gear. There’s a time ring that bolts on there and what happen is 1/3 of it broke off. If you put a good scanner on it you can watch it read rpms and go to zero for a split second.