Q: How to drain coolant and remove and install the coolant temperature sensor on Cadillac ElDorado?
A: Never open, service, or drain the radiator or cooling system when hot, as serious burns can occur from steam and hot coolant. When draining engine coolant, be aware that ethylene glycol antifreeze can attract pets, which may ingest it from uncovered containers or puddles, leading to fatal consequences. Always drain coolant into a sealable container, and reuse it unless it is contaminated or several years old. The coolant temperature sensor, a thermistor, is mounted in the engine coolant stream, with low coolant temperature producing high resistance and high temperature causing low resistance. The PCM supplies a 5-volt signal to the ECT sensor and monitors the terminal voltage; high sensor resistance indicates low temperature, resulting in high PCM terminal voltage, while low sensor resistance indicates high temperature, lowering the terminal voltage. For 4.5L and 4.9L engines, relieve cooling system pressure, ensure the ignition is off, detach the electrical connector, and carefully remove the sensor. To install, coat the sensor threads with sealant, tighten to 15 ft.lbs., attach the connector, and check coolant levels. For the 4.6L engine, allow the cooling system to cool, partially drain it, disconnect the throttle control cable, remove the cruise control servo and bracket, detach the coolant sensor connector, and remove the sensor from the manifold. To install, apply a non-hardening sealer to the sensor threads, tighten to 106 inch lbs., reattach the connector, reinstall the cruise control servo and bracket, connect the throttle control cable, and fill the cooling system.