Electronic autometer speedo goes wild after short drive

[Bowtieracing]

Originally Posted by AAW_Theresa

Check your ground on the sending unit wire coming from the trans.

If you do have good continuity to ground, then it looks like there's a good possibility that you have a simple calibration issue with the unit itself.

I'd then suggest you contact Autometer.

Thank you Theresa!!! Okay i check the ground first. That has come to my mind too. But i dont think its the calibration,because it works like a dream first 10 miles.

I did email to autometer tech.They just said ; take the power lead of from the alternator and see what happens. I have asked around and nobody suggest to diconnect that wire off. I am afraid it could toast the ecm ?