2002 Ranger 2.3L Thermostat problem
2002 Ranger, 2.3L engine, 60,000 miles. As I'm driving down the Interstate the check engine light comes on again. I've got the Actron scanner handy because it's just did this the day before, and I plugged it in to reset the P1432 code. I looked at the "vehicle" data while driving and saw that my coolant temperature was 260 degrees even though the dash guage showed "normal" temperature.
Next day I changed the thermostat ($120.00 thermostat with an electrical plug on it), filled it and tested it, got the same thing, Dash guage showing normal, Actron showing above 250 degrees Farenheit and lower hose between thermostat and radiator cold. I used an infrared thermometer to view the hose temperatures, the top hoses, including to the Overfill/fill tank were very warm, but the lower hose was as cool as the outside air.
Took thermostat back, got different one (same brand) and tried that. Same thing. Took Truck to local shop and told story.
They called back, looking into what might be the cause. Said something about the thermostat being electrically controlled by the line that plugged into it. I thought that line was a "temperature" monitoring line, but it looked fine, the plug was good, not burned or frayed where I could see it. Dash guage appeared to work, moved from cold to normal, but never moved above that level even as the Actron showed the coolant temperature rapidly building.
I wondered if anyone had experienced this, and could suggest anything to fix it. I don't want to remove the thermostat all together, but it seems illogical that two thermostats were bad (not including my original). I don't know about the "electronic controlled thermostat", is that a possibility? I dropped it at the shop shortly before they closed so their preliminary diagnosis was just that, I'm sure they'll look at it more thoroughly, but I want to have some idea what to expect when they call, or a place to point them in case they don't have a quick answer.