helllo to all!

1994 4x4 ctd auto
started out with tack going out when engine was cold.
now tack and speedometer go out intermitenly.
can sometimes get all back by restarting but less often,
both will go out while running,with engine warm and
restarting at 45mph and getting in to overdrive before tack
goes out it will stay working all day no matter how many times
I shutdown???
speed sensor has 3 wires 8volt,5volt,and ground all good.
after serching at tdr I spliced into ground wire and went
to block and battery.no change.
can the sensor be bad and still work?
why would the speedo go out?
could it be a bad ground at pcm?
thanks, bill

 

ok so I changed speed sensor $110. and tack has gone out once
in 2 days.
Has any one here had abad body ground or pcm ground?
If so what did you do to fix it?
has any one had a problem like this?

 

lost 8 volt,now reads 1.8 at vss [speedo] and .7 at crank speed
sensor.
any help?
has any one had a problem w/ pcm?
thanks