I use PFC with FC-Datalogit and now I change the new engine but my PFC read Water Temperature Sensor 175 C forever not change to any value. I check sensor, so it's functional. I have no idea to check and solve this problem. Please help me.

My car is FD3S 1st Gen(1992 JDM).

1st gen is fb 79-85

2nd gen fc 86-92

3rd gen fd 93-95



how did you check the sensor

should be a way to chech with volt meter if you new what it should read

anyone else care to jump in??

Sorry! My car is FD3S 1992



I checked resistance of sensor, so it's functional. I checked wiring, so it's OK. I checked voltage from water thermo sensor connector from PFC When Ignition switch is ON, No voltage from PFC. Is my PFC broken? or something else?

sorry for the delay

im not a pfc guy but i found this on another forum from a pfc guru





The ECU supplies voltage +5dc to one side of the sensor from pin 3E and the wire is green with a white stripe. This is the hot lead/side of the circuit going to the sensor connector. The other wire from the sensor connector is brown with a black stripe. This wire goes to ground.



The sensor is a thermistor . See page F-183, at 68F it is 2.2-2.5Komh, at 176F it is 290-350ohm.



The ECU monitors the voltage drop across this resistance that varies as the water temperature varies. Hot sesnor means low resistance thus the voltage is closer to ground or low voltage. Cold sensor is opposite thus a high voltage at or near 5volts.



Thus there are three components of the circuit to test. Does the sensor connector have the 5volts from the ECU? Does the sensor resisitance vs temperature match the specs? Does the gound side lead go to ground(no voltage and almost no resistance between the connector and the wiring harness ground.



A final circuit test can be done with the sensor plugged into its connector but not screwed into the waterpump housing. Cool the sensor in ice water, plug it into the connector, turn on the key and observe the voltage as you heat the sensor with a hair drier. The voltage should drop from 5 volts as the sensor warms up.



If the first three test past and this final 4th test fails, the PFC or the commander are bad.

My guess is that you have swap the wires.



Recheck all your wires and make sure its not cut or short circuited. PFC also has a setting where you could check all your sensors. Its a great way to check to see if all your sensors are working properly.

Now, The problem is silved. My water temp sensor is malfunction. Just change and don't forget to reset PFC(disconnecting battery ground at least 20 seconds and depress on brake pedal before reconnect ground). Thank you for all reply.