Engine management fault light on?

System fault in ECM is "5286-p0121 Throttle position sensor (G69) implausible signal - short to plus???"

Throttle pedal position sensor has been replaced & has not fixed the fault!

After system code reset the fault code only seems to return when the vehicle is cranked & started?

If you reset the system with the engine running the code will never appear while driving until switching off & then restarting???

Seems that the cranking of the starter effects the throttle position sensor???

any ideas?