I have solved the mystery.

as weird as it sounds ALL my problems came from the OVP..... what the ****

the OVP simply cut out my engine check light and speedo making it look as though the speedo itself is a lone problem.... then together with other symptoms of the OVP I had stalling idle (<500rpm speed) and ABS light.

one swift re and re of the OVP later and it all came back online....

what a stupid design...