PROBLEM: The radiator fan does not turn on when the engine gets hot, however the fans turn on when the A/C is turned on and cycles on and off when the A/C is on but when the A/C is turned off the fans dont turn on at all. The temp goes up to half on the gauge.
TEST: Carry the car for a run and return home (without A/C), the temp goes up to half at this point the fans didn't come on, so I am thinking well it's passively cooled while driving so I will leave it on and rev it to 2000 RPM for about 5 mins, fan still does not turn on, however the temp gauge reads half, turned the A/C on and the fan turns on. The temp on the radiator feels close to 100 degrees C.
COOLANT TEMP SENSOR/SWITCH: TESTED OK: Tested this with a multimeter and some diagnostics SW, heated it up to 90 degrees C and the resistance read 200 ohms, when cooled to ambient temp it read 1.5 K ohms. I changed it anyway cuz I bought a genuine nissan one thinking that this was the problem in the 1st place.
THERMOSTAT: TESTED OK: Did the same test on this, heated up to 90 degrees C, it opened at 77 degrees. Well to make myself feel better I did NOT install the thermostat and ran the same test as b4 but the fans still did not turn on. Engine temp goes to half. Fans did turn on when the A/C is turned on. YES I reinstalled the thermostat.
RADIATOR RELAY: TESTED OK: Checked continuity between terminal 3 and 5, 6 and 7 test read N.O without 12v applied to terminal 1 and 2 and test read NC with 12 v applied to terminal 1 and 2. Could even hear the relay clicking sound.
PCM/ECU: Using nissan schematics I did a voltage test between terminal 70 (wire that goes to the coolant temp sensor/switch from PCM) on the PCM to ground. According to Nissan this should read 0.9v when engine is @ 90 degrees C, however mine read 1.3v @ 90-100 degrees C. Temp gauge remains at half during this test.
Thursday, November 30th, 2017 AT 6:27 PM