Speedometer question ? jumps from 0 to 45mph

[S14Driftr91]

In my s14 cluster, my tachometer was broken so recently i got a new tach and swapped it into the original cluster a few days ago. today when i was driving i noticed my speedometer not working. if i came to a stop the needle would go to 0, like it should but when i would start off it would suddenly jump to 45mph and remain there while i was easily doing 15mph or whatever.... has this happen to anyone before ? and does anyone how to fix this? maybe a bad wire or speed sensor possibly ?

thanks for the help guys !

[Smurf_240SX]

Its possible that's its a faulty speed sensor.

[slider2828]

I dunno if SR or KA, but I think that is the yellow with green stripe wire... Check if it is loose at the ECU level. Then check and clean plugs on speed sensor located at the rear of the tranny. Its the roundest looking sensor on the tranny.....

[S14Driftr91]

yup, forgot to mention its a Ka.