my speedo sometimes bounces around and shows i am doin like 10km/h when in fact i am doin 100km just wondering if maybe i have a bad ground? any ideas?

 

Could be a bad ground but more likely is the connection on the vehicle speed sensor or the sensor it self on the overdrive unit of the trans. is the ABS or BRAKE light on, if so its possible is the rear wheel speed sensor. i have only seen that once so i would really lean on a ground or the VSS (vehicle speed sensor)

Chris