just driving around and for the past 2 weeks my tachometer goes to zero and after a while goes back to actual rpm. I have an edge juice and the rpms are correct on it. Am i looking for a grounding issue? bad sensor?

a year ago I tore up my tranny pretty bad and got a lot of chunks of aluminium around the flex plate. I wasnt going to worry about this until I had a hell of a time getting it started


thanks

 

update....now the truck just wont start, cranks and cranks but wont start. put a code reader on it and along with 336 i now get 1688 and 1689
my mech says it mite be due to the bad sensor sending erroneous codes for the vp44?

anyone seen that before?