My speedo has swung over to 120 mph and is staying there. Had an issue a couple of weeks ago where I lost all power to the car. I have since fixed that problem and now noticed that my speedo is pegged. The car is an 88 Formula 4-speed with a SBC. Any suggestions? New stepper motor?
Thanks Chuck
phonedawgz
AUG 08, 10:02 PM
The Fiero gauges use air core drives, not stepper motors. Rarely they go bad but the can. Air core gauges work like old time electromagnet vs spring, but instead of a spring it ends up being electromagnet vs electromagnet. But since there is no return spring, if the needle get's stuck on the right side, since there are pins to keep the needle from going around the bottom end, it can get stuck there.
How to fix it? Drive the car faster than the mid speed on the speedo. 60 MPH. Once you do the needle should jump to where it needs to be.
Any chance you lost power while going over 60 mph? If so that did it. That left the needle at a position somewhere past 12 o'clock. No spring to return it so it just stayed there. Then powering it on next time at 0 mph brought the needle down on the wrong side and then you got what you got.
[This message has been edited by phonedawgz (edited 08-08-2019).]
eyewall
AUG 09, 03:30 PM
That is exactly what happened! Thanks for the detailed explanation. I learned something today!
