acturner

Does anyone have information about this TSB. From the description, it might be the issue I have, so I'm curious as to what the fix is. Thanks

Has anyone else noticed their temp gauge moving around slightly? History: driving home the other day and CEL comes on. Car is running fine, no hesitation, no coughing, gauges look good, no other warning lights. So I don't worry about it. I get home and pull out my scan tool. Trouble Code P0128, ECT below Themostatic control. Hmmm, maybe thermostat has failed. I do some searches on this forum and convince myself that this is the issue. Not a problem, I'll order a thermostat and I'll change it when I get the time. Since then, I've been watching the temp gauge while I'm driving (of course I never really paid that much attention to it before) and I notice it moves around way more than I thought. Driving around town and cruising down the highway the needle on the temp gauge almost covers the little themometer symbol and sits there, so the engine gets up to temp ok (this goes against the idea that the thermostat is stuck open). If I step on the gas pedal to accelerate quickly, pass another car, etc, the trans downshifts, RPMs go up, speed increases and I can watch the temp gauge go down slightly. Messing around last night I shifted to L-range and held the RPMS at 4000 going 70mph on the interstate for approx 20 to 30 seconds (so water pump is moving lots of coolant and lots of cool air going through rad), the temp gauge dropped from the middle point covering the thermometer to the edge of the wavy lines on the gauge. It never went any lower, so it never dropped all the way to the "C" mark. Now I'm wondering, does the edge of the wavy lines represent the termostatic control limit (ie my thermostat is fine and works as normal) or possibly just the limit of the cooling capability of the ambient air passing through the radiator last night? It does seems like the car takes a bit longer to heat up than before, but again I never really paid to much attention to it before the CEL came on. I will try to borrow a scan tool with real-time data to see what the ECT is as the gauge moves around. This may tell me if the thermostat is OK or not. Does anyone know what the ECT control temp is (165, 175, 185degF)? Thanks for the input.