As posted before getting the numbers to change might not mean that the warning changes as well. I tested mine by fooling the DME with a decade box across the temp sender wires and tracked the temp with impa but the warning lite did not come on when the temp read over the setting. That was a while back but I think I remember not being able to get any reaction from the guage or the DME from the gauge side of the temp sender maybe I didn't try putting the decade box on the guage side and it is only used for the warning light?? Interesting for sure and would tie up some loose ends on how the system works!
I might dig into the E-box for another project so maybe I will revisit some of this. Just want to add that I have the low guage cluster so all bets are off on how things work with the high cluster.