Recently removed my dash pod gauge cluster to replace the inoperative temp gauge.

All the connectors (5?) for the cluster were like new, except for the one on the upper left.

Grounds are intact and not rusty, so before I start digging is there any common theme with Fiero for this condition?

(Note: My dash light dimmer transistor recently went bad, wonder if its related)

[This message has been edited by Skybax (edited 06-21-2021).]

I've clean that corrosion using steel wool and they shine like new copper. Just be gentle.

Spoon

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"Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut

Seems like acid or dirty water did this.
tach and speedo have small parts that maybe can leak small amount of acid. Should check the rest of the back and inside of dash for acid eating there.

Must clean them.

On the plug Have to pull one terminal at a time and clean the metal and plastic. Don't remember where the terminal release is or how it works w/ that one.
⚠️ Dash side is easy to wreck the copper because cleaners etc can eat the glue if not already stop sticking.

Then use DeoxIT to prevent rotting out again. https://www.amazon.com/Hosa...leaner/dp/B00006LVEU
DeoxIT is a cleaner but that much green needed removal and maybe neutralize acids/bases before spraying.

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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

Typical of most Fiero dashes - copper turns green due to oxygen in the air.

A pencil eraser will clean it off without disassembly.

The contact, even though it is corroded, still appears to be making a connection based on the noncorroded area in the middle - I doubt it caused any problems.

Thanks, car is in excellent original condition and was garage kept all its life with ideal storage conditions, and other 4 connectors to cluster were like new.

So its not a bad environmental issue, IMO the connector was not fully seated, resistance somewhere, or other... (i.e. bulb, socket, ground, dash dimmer, etc).

Thought maybe it was commonly known thing with Fiero's, I don't have a wiring schematic but my guess is that connector is for lights, dimmer, or similar.

I already cleaned up the connectors, was thinking about using a very thin layer of silicone dielectric grease when I plug it back in, but my hesitation with that is some of that stuff is conductive (like bulb grease they sell in packets) and some is non-conductive (like stuff they give you with ICM even though you should only use thermal paste on ICM).

If anyone knows what those wires operate please let me know, that will help me to check on the other same-circuit areas (I really need to get a Service Manual).

[This message has been edited by Skybax (edited 06-22-2021).]

"Bulb grease" is Not Conductive.
This never dries and won't run at high temps.
GM and others use this when light fixtures and many other plugs won't seal out water like many relay plugs and Fiero C500.

Most Dielectric Grease have Silicone Oil and will run even at "room temp" but slower.
Side Note: Many "heat sink" greases have same issue/problem too Even most of ones that say silicone free.

DeoxIT will flow into very small spaces w/o you having to take things apart again. And doesn't need a lot of it to protect and safe for plastic.
Other "contact cleaners" are like that but read directions/warnings. Some will dry completely w/o anything left behind, not plastic safe, etc.

Thanks for posting that image, ironic that my problem areas were related to that connector (dash lights/dimmer, temp gauge).

Yes Ogre you are correct, non-conductive, my brain malfunctioning again.