I recently bought a 1995 Marquis with 120,xxx miles, the temperature gauge does not work it just stays pinned below the Cold level. I have replaced both the sending units the one behide the thermostat and the one on the other side of the intake and it still does not work. Any ideas on what to check next, possible short maybe ?

 

I had this issue on an 85 pontiac and hadd to re-run the sense wire to the gauge. In this case though, the dash is electronic even if it has needles and it may be a case of a trace gone bad or a corroded connector. Pull the cluster out and check the connector on the back for the chunky goo (corrosion) and clean it. Hopefully a little contact cleaner will sort that issue for you. You may need to check the traces that go to the temp gauge and make sure that something isn't fried. If something is fried, then there's a short somewhere that needs to be solved first before jumping the trace with a wire to fix the gauge.

 

Thanks your advice made me discover that the gauge itself was faulty.