Mercury F77Z-12A648-AA Sender Assembly

Allow the cooling system to completely cool down. Drain coolant from the radiator to approximately four inches below the upper radiator hose to minimize coolant loss during this procedure. Disconnect the electrical connector from the top of the sending unit. On 4.0L SOHC V6 models through 2000, the upper intake manifold must be removed to access the sending unit. It may be possible to access the sender with the thermostat housing removed. Wrap the threads of the new sending unit with Teflon tape. Remove the old sending unit from the engine. Install the new sending unit and tighten it securely. Connect the sending unit electrical connector. Refill the cooling system. Start the engine and check for leaks.

It is important to conduct extensive testing during the diagnosis of an Engine Coolant Temperature (ECT) sensor. The ECT sensor, like the IAT sensor, keeps track of coolant temperature and changes resistance as it fluctuates. Trouble codes can be set off by circuit faults in the ECT sensor; moreover, this may occur due to a defect in the sensor itself or in wiring and connections. On certain engines, there are two coolant temperature sensor units; one for the instrument panel temperature gauge and another for the Electronic Engine Control (EEC) system. By disconnecting the ECT sensor and using an ohmmeter, one can see different resistance values. Make sure the right resistance is there and check the reference voltage also. To replace this part of your car's engine, cool down the motor first; then put Teflon tape on the threads of the new part before unscrewing the electrical connector plug from the old ECT sensor, attach the new one quickly and firmly bolt into place again securing tightly. Finally, reconnect the electrical connector and check the coolant levels.

On 2001 and later 2.3L engines, the sending unit is located at the rear of the engine mounted into the coolant outlet pipe.

Wrap the threads of the new sending unit with Teflon tape, remove the old sending unit from the engine, place your finger over the hole in the engine to minimize coolant loss, and immediately install the new sending unit and tighten it securely.

To replace the Crankshaft Position (CKP) sensor, disconnect the battery, remove components like the accessory drive belt or alternator, unscrew the sensor, and install a new one with specific alignment procedures for different models.

Issues with the ECT sensor can be caused by wiring problems, faulty connections, or a malfunctioning sensor itself.

Install the new sending unit and tighten it securely.