Gen3 conversion speedo issue

Hey guys have a strange one have just done a gen3 turbo transplant into a 95 na aus delivered.
have systems checked everything and it is all happy other than the speedo is not working.
Once it warms up and you hold the revs over 2,000 for more than 8 seconds it throws code 42
which would make sense if the speedo is not picking up a pulse.
Any of you guys out there have any ideas?
in answer to the anticipated question the loom going to the front of the car has been also changed
with the matching 3sgte loom.
Thanks in advance
Phil

Problem solved interesting the aus delivered gen3 Na different to all other JDM wiring set ups.
the sensor wire does not go to the front plugs in the loom as it does in nearly every other SW20 set up it terminates in a plug on the inside of the car at the front firewall then runs down the right side of the tunnel up to the wiring in the dash panel. Once we established what wire in the new loom was the sensor wire it was a case of running an extension wire back to the plug on the inside of the firewall and presto speedo works.
in all the conversions I have done over the past 10 years or so this is a first worth noting.
Cheers
Phil