Toyota 89422-20010 Sensor, Water Temperature

Check the fuses if the coolant temperature gauge isn't working. If the gauge reads hot soon after starting a cold engine, disconnect the wire at the coolant temperature sending unit. If the gauge drops, replace the unit. If it remains high, there could be a shorted wire or faulty gauge. If the gauge doesn't indicate after the engine warms up, connect the wire at the sending unit to a clean engine ground. If the gauge reads hot, replace the unit. If it doesn't work, there might be an open circuit or faulty gauge. To replace the unit, release radiator pressure, disconnect the wiring harness, apply sealant to the new unit's threads, and quickly install it. Tighten it, reconnect the wiring, refill the cooling system, and check for leaks and gauge operation.

Check the fuses if the coolant temperature gauge is not working. If it shows excessive temperature, refer to the manual's Troubleshooting section. If it indicates HOT immediately after starting a cold engine, disconnect the wire at the coolant temperature sender. If the gauge reading drops, replace the sender. If it remains high, the wire or gauge may be faulty. If the gauge shows no indication after warming up the engine and the fuses are OK, disconnect the wire at the sender and connect it to a clean engine ground. If the gauge indicates Hot, replace the sender. If it doesn't respond, the circuit or gauge may be faulty. To replace the sender, drain the coolant, disconnect the wiring connector, remove the old unit, install the new one without thread sealant, reconnect the wiring, refill the cooling system, and check for leaks and gauge function.

All the mentioned components are covered by an extended warranty mandated by the federations; therefore, it is impossible to check or replace any of the, while still under warranty; but after the warranty expires, all with the exception of the oxygen sensor and the ECU can be checked and replaced. To inspect the EFI main relay, in engine compartment fuse panel, switch on the ignition key light, and if it has clicking sound, then relay operates fine, otherwise its resistance has to be measured. For models that were produced between 1979 and 1981 make sure there is continuity between the terminals and check the resistance; for the later models the continuity should exist and use battery voltage to check for operation. The circuit opening relay of the compressor is located in a different position in various models of the car, its operation should be examined fist and then the resistance measurement. The resistance of solenoid resistor should be the one recommended by manufacture for specific model. Most coolant temperature sensors have less resistance as the temperature rises; therefore, if the resistance does not change, replace the sensor. When it comes to the fuel cut RPM checks, the procedures vary according to the model year and involve bridging terminals and checking RPM. Continuity and resistance must be tested on the fuel pump relay and the resistor and the high temperature line pressure-up system must check whether the vacuum switching valve is operational with the right amount of resistance. The High Altitude Compensation System's sensor shall make resistance measurement, and the EGR gas temperature sensor shall be checked in hot water. The functionality of the oxygen sensor can be determined by methods such as voltage and deflections and the methods differs with the model year. It will only be appropriate to check the sub-oxygen sensor when a certain code is on while the throttle position sensor needs to be bench checked and might even need to have its continuity altered. Cam position sensor is for turbo only; ECU should be replaced only if faulty according to a dealer, and there is a detailed method on how to remove and install it.

To troubleshoot issues with the coolant temperature gauge, start by checking the fuses if the gauge is inoperative. If the temperature indicator shows excessive temperature after running for a while, it may indicate a problem. In the case where the gauge indicates "Hot" shortly after starting the engine cold, disconnect the wire at the Coolant Temperature Sensor. If the gauge reading drops, replace the sending unit. If the reading remains high, there may be a shorted wire to the gauge or a faulty gauge. If the coolant temperature gauge fails to indicate after the engine has warmed up and the fuses are fine, shut off the engine. If the gauge still doesn't work, there may be an open circuit or a faulty gauge. For replacement, start by releasing any pressure in the radiator by removing and reinstalling the cap when the engine is cool. Disconnect the electrical connector from the sending unit and apply sealant to the threads of the new sending unit. Unscrew the old sending unit and quickly install the new one to prevent coolant loss. Tighten the sending unit securely and connect the wiring harness. Refill the cooling system, run the engine, and check for leaks and proper gauge operation.

The ECT sensor is a thermistor that sends a voltage signal to the PCM, which is affected by changes in resistance values as the sensor temperature increases or decreases.

This part goes into a water jacket on the engine block

This sensor reads the temperature of the coolant