I bought my fiero that had had the pegging issue it's whole life and the owner never bothered to fix it. I did the wire swap and I've replaced the sending unit and swapped wires there too. Everything went well now the coolant temp warning light comes on for a second like it should! The needle for the temp gauge had fallen far below (or above) the lowest temperature and when hot seems to rise to maybe 60°. I was wondering if it's possible to replace just the gauge itself instead of having to wire in a new ugly looking seperate gauge. I've read about zeroing the gauge with resistors so I may try the later tonight but the needle seems far too loose and too far gone. If youve run into this I'd love to hear how you fixed it! [font=Arial][/font]

Never trust dash gauges for most older cars.
Because Gauge(s) and senders are often fine but wiring to it have problems and won't read right. Even 1 iffy ground can make a gauge or all to lie to you.

Oil pressure is another example... I replace OP sender then the tack w/ OP because are bad and even now still reads very high even w/ known good resistors to check ½ and full range of meter. IOW ~45Ω resistor between sender plug and block is 80psi? I don't think so.

Is a hidden resistor on the WT Fuel and OP gauges too. (FSM and other docs do not cover this.) Often the resistors can get loose etc and gauge doesn't work right. You need to pull out the gauge(s) then loosen/tighten the resistor nuts are few time to "Clean" the connects. Don't use any chemicals on the resistors. Don't tighten too much or will wreck the resistor. These Nuts only snug whatever parts and need very little torque.
Fuel and OP are exact same setup because both uses 0 − 90Ω senders. WT resistor is not and can't switch w/ others.

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Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

[This message has been edited by theogre (edited 11-15-2018).]

"Never trust"...... Well, I don't know about "Never". Mine are working pretty good.....

Is it just the needle not reading correctly now then? You could try pulling the needle with the ignition on and putting it where it supposed to be. I had to do this after doing the wire swap as well.

I would have to agree with, "Spadesluck"... If the needle is loose, your reading is off. You might try getting a newer needle at the wrecking yard from a GM car or try the mall section of the forum.