Engine coolant temperature sensor circuit diagram. The less common options were the 50 liter v8 74 liter v8 and some kind of a diesel engine. Details the operation of the engine coolant sensor ect. 2 fan motors 3 relays control unit and the coolant temperature thermistor ntc. When the sensor is functioning properly it will tell your on board computer if the temperature is too high alerting the driver that a problem exists.
This can cause the computer to incorrectly compensate for a lean signal which can result in overheating and even misfires or engine ping. The ect is one of the main inputs to the ecm. At normal engine operating temperature 85 c to 95 c the voltage will measure about 15 to 20 volts at the ecm. After the engine start coolant temperature begins to rise.
Perhaps somebody could post a schematic for a 1998 57 liter gm v8. At 90 oc its resistance is in the range of 200w to 300w. As the engine warms the sensor resistance becomes less and the voltage drops. In cold engine and an ambient temperature of 20 oc the sensor resistance is between 2000w and 3000w.
The ect usually located in a coolant passage just before the thermostat. Another symptom of a problem with the coolant temperature sensor is an overheating engine. A defective sensor can also produce black smoke from the exhaust pipe since more gas is being used than necessary. If your coolant temperature sensor isnt working efficiently your check engine light usually warns you of the hazardous heat thats affecting your vehicle.
Ect gradually heats and its resistance reduces proportionately. Ops truck most likely has a 57 liter v8 or a 43 liter v6. When the engine is cold the sensor thermistor resistance is high therefore the ecm will see high signal voltage. The engine cooling fan system is made up of the following parts.
Usually a two wire sensor a 5volt reference from pcm powertrain control module and ground signal to pcm. The ect engine coolant temperature sensor is basically a thermistor that changes resistance with temperature. Engine coolant temperature sensor circuit diagram. The ect is a thermistor device with a negative temperature coefficient.
The coolant temperature sensor can also fail in a manner that causes it to send a permanently hot signal. The ect is connected to the thw terminal on the ecm.