Help us help you. By posting the year, make, model and engine near the beginning of your help request, followed by the symptoms (no start, high idle, misfire etc.) Along with any prevalent Diagnostic Trouble Codes, aka DTCs, other forum members will be able to help you get to a solution more quickly and easily!
HI, WHEN I JUMP BOTH PINS TOGETHER ON THE ECT THERE NO RESPONSE ON THE SCAN TOOL ALTHOUGH AT ONE STAGE IT SEEMED TO GO TO -40 DEGREES. WHEN I GROUND THE 5V REF ELSEWERE THERES A RESPONSE, IT GOES TO MAX TEMPRETURE BUT INTERMITTENTLY, COULD BE WERE ITS GROUNDED?. THERES 4.87 VOLTS ON THE SIGNAL WIRE UNPLUGGED AND READS 0V ON THE GROUND WIRE. IM NOT SURE WHATS HAPPENING HERE COULD YOU SHED ANY LIGHT ON THIS ISSUE, THANKS.
Generally if a PCM detects a value from a temperature thermistor outside the expected range it will simply ignore the sensor and use a substitute value.
" We're trying to plug a hole in the universe, what are you doing ?. "
(Walter Bishop Fringe TV show)
Little side story. Had a commodore in yesterday, same motor as a US 3.8 Buick, that had a coolant temp sensor code. I recently bought a test lead kit that has two variable resistors in it so thought I'd have a little play.
If I moved the resistor slowly I could cycle the temp reading from cold high idle to high temp and make the cooling fans run. But if I moved the resistor too quick the ecu flagged the signal as implausible and set scan data to 53C and ran the fans continuously. Even if I unplugged my resistor scan data stayed the same.
My point is if you have a code and the data seems a little bit suspicious I'd ignore it.
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