Have a 2003 ranger edge, 4x4, 4.0, 175,xxx miles with some temp problems. The temp gauge stays right below the middle when warmed up, but the computer is reading upwards of 330-360 degrees on my scanner. CEL is on and when cleared it stays off for around 250 miles then comes back. Says coolant temp below threshold. The truck runs pretty good, the only issue in driving I've noticed is a hesitation within the first few minutes of startup, especially when cold out. The ac also only works randomly since this has been going on but it can be jumped and works like it should. I've replaced the thermostat and both temp sensor/sender. Really not sure where to go from here. Do these parts need to be motorcraft? I'm sure I just put in whatever they had at the parts store. Hopefully not looking at a bad computer. Thanks in advance for any help

 

Welcome to the forum

What does the ECT temp read before cold engine start up?
Should be local outside temp in Rutherfordton

Turn off the key and unplug the ECT sensor, the one with the green/red and grey/red wires
Turn on the key and see what ECT temp shows, you are checking for short in the wiring.....or computer

ECT is a 5volt sensor
its sends back 3volts when cold, just under under 1volt when hot, 185degF
300deg, could be a short to ground, i.e. 0volts
Some OBD2 readers also have "voltage" option for ECT, check if yours does to see the voltage return, vs temp in deg

ECT Graph here: http://www.grandmarq.net/oldfuelinje...emperature.gif

 

I will check once it has cooled completely either this evening or in the morning. I cleared the code yesterday and normally comes back after 200+ miles. CEL came back on today with a p0117 code ( engine coolant temperature circuit low input). I have a cheap Amazon special scanner but I will check if it has that feature. Thanks for the quick reply! I'll get back with results soon

 

Haven't been able to completely unplug the connection yet, but I did partially unplug it as best I could and wiggled the connector a bit. Checked temp truck temp before and it showed 131 degrees, after messing with connector it showed 62 degrees, outside temp was 58. Took it to work maybe about 5 miles away and it warmed to around 190 and stayed there. Does this mean I have a bad connection on that plug going into the ect? I replaced the plug itself with a junkyard unit that looked identical a while back, but it didn't fix the problem. Please bare with me, im not the best with wiring and electrical.

 

Still having the same issue, today the truck started to jerk and buck going down the road around 55 mph. Almost felt like a sudden misfire/hesitation and happened multiple times at different speeds and rpms.
Does anyone know where to find a wiring diagram for the ect system? Once i find some time i will start digging into the wiring unless someone could point me in the right direction