The coolant temp sensor shows to be in the thermostat housing. I can't say that the sensor is faulty? The pcm may use a 5 volt ref signal to the sensor. The other circuit is ground. High resistance through the sensor when engine is cold. As the engine warms up, the resistance to ground through the sensor starts going down, the ref voltage starts dropping, the computer monitors the ref voltage. I can give you resistance spec for the sensor at different temps. You can use a digital multimeter to check voltage and ground at the sensor connector. With the key off, take connector loose from sensor, place meter leads between wiring connector terminals, turn the key on, you don't have to start it. If the meter reads close to 5 volts, you have voltage and ground.
Generic specs for sensor resistance, 3400 ohms at 70 degrees F, 1600 ohms at 100 degrees, 185 ohms at 212 degrees.
Saturday, May 22nd, 2010 AT 10:54 AM