Astra J GTC problems

[Yazza54]

Hi guys

Does anyone know where the speedometer sensor is on my car? It's a 2.0 CDTI GTC 2012... I have a bouncing speedo and ABS/TC lights on. Not ideal with winter drawing in. Clearly all the problems are linked, but I can't seem to find a speed sensor on the box, unless the wheel speed sensor drives the speedo as well as work the ABS/TC?

[M32Guy]

On the older Astra H the speedo worked off the passenger front ABS sensor. I would get the codes read to confirm exactly what's playing up