I'm trying to trouble shoot my pegged Temp. Gauge. With a search, I saw a fix for this, but the link is no longer available.
In the meantime, I tested the sensor Cold and Hot, and am getting a continuity reading after it was heated up. I used a test light, with the key ON, at the wire harness connector for the Temp. Sensor, but could not get the test light to go on. So I am guessing that I am not getting power to the Sensor.

Is there a more common area where the wire may tend to have a break?
Which Fuse handles the circuit for the Temp. Gauge?

Thank you for the help with this issue.

Does the temp gauge stay pegged or go back to something normal when the car is running?

https://web.archive.org/web...ls.com/tempgage.html

Do Not do any version of Temp Fix right now. That only solves pegging when starting.

Gauge pegged other times means most sender line is open same as sender not connected.

Sender wire can be open anywhere for many reasons.
Sender goes thru C500 Pin C2 for most years. Check there next. Also Ω test engine side to sender plug.

Gauge and Dash back often have problems.
Common examples:
Dash back "baord" looses "glue" holding copper where Big plug(s) go in and copper moves even shorted out.
Gauge "bolts" have loose/corroded nuts. When tighten, barely finger tight w/ nut driver shaft or if use a wreck fingers only near the head.
SS Clips between Gauge bolts and Dash back can get crap connection. Back plastic warp some over decades of use and clip get little/no tension to copper on back

Correct Light and Gauge layout for dash is here... https://www.fiero.nl/forum/Forum2/HTML/138175.html

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[This message has been edited by theogre (edited 12-05-2021).]

Thanks for the suggestion Ogre.
Mine is pegging so bad that it gets stuck. Ill check all the connection points and clean them up. Maybe slap some dielectric grease on them.
In addition I replaced the fan switch sensor. When I ground out the wire it works....its still not kicking on the fan though. Will check from the plug.

quote Originally posted by Forrest: In addition I replaced the fan switch sensor. When I ground out the wire it works....its still not kicking on the fan though. Will check from the plug.

If you used a replacement stock fan switch, the fan won't kick on until engine reaches 235F.

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3.4L Supercharged 87 GT and Super Duty 4 Indy #163

Pulled the gauges. Used a wire brush on the fuel/temp posts as well as the pins that connect to the cluster. Reinstalled...no more pegging.

@FieroSound
I pulled the connector and tested directly where it connects to the sensor...grounded it out and the fan does come on so this seems to be an issue with the sensor.
At least according to the gauge it was almost in the red. On my sons 88 the fan kicks on when the temp needle gets just past the middle. Might need to order the one from Rodney Dickman. For now I am going to have to just ground it out. I live in SE Texas so the motor being too cold is not an issue.