I thought I remembered seeing your description of poking the blue wire to read the voltage. That is one thing that impressed me about the Problem Solver. It is the best way, in my opinion, to verify the engine coolant temperature sensor's operation, because you can watch that voltage fall as it warms, and be assured the sensor isn't intermittent with temperature.

My technique is to backprobe at the ECU connector -- a little less convenient inside the car, but long ago, and I mean close to 45 years ago, I abandoned the convenience of poking through wire insulation under the hood after seeing the result of my little invasion after the moisture turned the copper wire to blue powder in a couple years. I suppose I should have wrapped the wound with electrical tape and all would have been OK.
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Art Benstein near Baltimore

Always read stuff that will make you look good if you die in the middle of it.