240 Temp gauge condundrum

[MarkEKaylor]

Howdy folks-

I've used this site and many other Volvo sites hundreds of times over the years to diagnose and find info on various ailments on my 240's. This is the first time I've had to join a forum because I've searched, read, investigated, checked, replaced, and just flat out gone in circles over the temp gauge on my current 240.
This isn't my first 240 and I've had temp gauge issues in the past that were always cured by bypassing the comp board or putting in a new thermostat.

Here's the lowdown on my current situation on my '89 245:

-bought the car last year, noticed then engine warmed up but the temp gauge never got past the 1/4 or so mark even after driving for along time. I had heat so assumed the thermostat was fine. Went ahead and pulled the dash console and removed the comp board, jumpered pins 1 & 3.
-after the above work the temp gauge read even lower, maybe not even going above the bottom line on the gauge
-I checked the wire for the coolant sensor. it looked good, I grounded the wire and turned key on, the gauge pinned to max, which I've read should show my wire and gauge are ok
-after the above test I deduced my coolant sensor was at fault (still seemed to have heat although wasnt' using it much as it was warm out)
-installed new coolant sensor from IPD, now the gauge read even lower, barely moving at all (it did move, but maybe 1/16" or so.)
-after all that it got cold outside and it did seem like the hear wasn't quite as hot as it should be, so, just to be sure I put in a new thermostat yesterday............and guess what? I'm back to a similar situation that I had in the very beginning......the guage moves maybe 1/4" when the engine is warm!

So I'm pretty freakin' stumped.

Two thoughts I had:
1) maybe my original coolant sensor was wonk and by chance I put in another wonky one from IPD (although I talked to them about that and they said they never have those returned for being faulty.........pretty unlikely to have a failure)
2)maybe the "check" for wire/dash gauge isn't fool poof.......I mean grounding the wire and checking seems to show the wire is good but how does it show that the dash gauge is fully operable?

I don't want to throw more money at this, although honestly I haven't spent much but plent of time researching, thinking, looking, etc.

Anyone have any thoughts?

Thanks in advance!!

Mark E. Kaylor

[93Regina]

Anyone have any thoughts?

Word for the day: Non-Contact Infrared Thermometer