Thanks, no hard feelings at all.
As I live about 2100 miles from you and haven't been to Detroit since the early 1980's when I was considering a job as an engine controls engineer
at one of the big four
(at that time
) auto makers, it is unlikely.
I decided against relocating there obviously, and chose a rather different engineering career instead.
Believe me though, I do
know how engine controls are designed and how they work...
BTW, one of the conditions I specifically encountered was a sustained run over the course of about half an hour and about 30 miles distance.
The vehicle speed was always above 60mph, the OAT was around 90F, and the A/C was off (so no fan).
These are all conditions that the ECU uses to determine the "need" for a shutter closure.
Despite running in the high 190's F prior to that, it suddenly began climbing up to 225F-230F as it did before my electronic thermostat mod.
Then on the return trip it did the same thing again after about 30 miles of highway driving.
If you do not duplicate those conditions you will probably never encounter the problem at all, to be quite honest.
Since defeating the shutters, there has not been even one repeat of this behavior and it happily runs now at around 196F-205F under basically identical conditions.
The problem with 176F as a mod is that we have draconian emissions testing here and it could
fail for various reasons if operated at that temperature.
If there had been a 195F option using your method (believe me, I searched for one) I definitely
would have tried it.
So it was just not an option for me.
Again, no disrespect for your method or original posts.
I am currently working on an elegant cheat of the fan controls to regulate the radiator output to a lower temperature.
I did this on another car and it worked like a charm but it may or may not work as well on the Cruze.
However, if that doesn't pan out I will just use a commercial secondary fan control thermostat.
In fact I already have one stuck away in a cabinet somewhere... if I can remember where I put it...