I finally cracked and replaced the ECT on my 1999 Lumina due to it giving rediculous readings (i.e. in a 4 second span it'd go from 1/3 to 3/4 without any change in actual temp measured at the t-stat housing). But now the dash guage hardly moves from the 100 mark (before it'd move with the temp change). I checked with a Tech2, the PCM is seeing the correct temperature as checked with an IR thermometer at the T-stat housing. But the guage barely moves at all.

I'd diagnose the cluster but it worked fine before I replaced the ECT..mighta something changed with the ECT design?

Sounds like the new part has higher resistance? Like they used to do with fuel gauge sender signals that varied to much, put a resistor inline.

That's what I don't get though. The PCM sees the correct temp, but somehow the PCM is sending the dash the wrong (or not varied enough) signal.

That's what I don't get though. The PCM sees the correct temp, but somehow the PCM is sending the dash the wrong (or not varied enough) signal.

So how was this resolved?

In my case the female terminal was bent, causing intermittient contact with the sensor's terminals. The damage looked mechanical, so I'm thinking the connectors were either forcibly seperated or incorrectly backprobed at one time.

In my case the female terminal was bent, causing intermittient contact with the sensor's terminals. The damage looked mechanical, so I'm thinking the connectors were either forcibly seperated or incorrectly backprobed at one time.

So did you simply 'bend it back in place' or replace the terminal altogether?