Temp Gauge not working

[lucas83]

Hey guys have my 83 spider and recently I've been noticing the temp. gauge isn't working correctly. On cold start up, the gauge will begin to climb normally and it seems as that when it gets to operating temp (just under 90 degrees) it will flicker randomly then eventually just shut off and fall back down to 0. Im figuring its a bad ground that moves once i begin driving.

Does anyone have any wiring diagrams by chance of the gauges? Or any info on why this might be happening?

Thanks,
Lucas

[So Cal Mark]

the gauge grounds through the sending unit, that's why the needle isn't pegged all of the time

[klweimer]

Brad Artigue is the master of Fiat wiring diagrams and has built a substantial collection of Fiat service documents, etc. He is happy to share his information at:
http://fiat.artigue.com
Kirk

[spider2081]

the gauge grounds through the sending unit, that's why the needle isn't pegged all of the time

The wire diagram I have shows the gauge grounds at a terminal strip above and behind the ignition switch. This ground is required for the gauge and the dash light in the gauge to work. The sender requires its own ground which is made by its installation in the head of the engine. There have been reports where people installing the senders use Teflon tape or other thread sealers that compromise the ground connection and prevent the temperature readings from being correct.

[4uall]

Just in case (for clarity) Fiat Temperature Gauge Sending Unit Identification

https://www.youtube.com/watch?v=8DtcIlkt4BY

[lucas83]

Thanks guy trying to take a look today. Also I will be doing a compete reseal on my engine so if anyone has any tips or tricks that would be great!
Merry Christmas guys! Thanks
Lucas